Supports adding trusted sources from SourcesViewController

Previously, only the beta version of AltStore could add sources. Now, the public version supports adding explicitly “trusted” sources, while the beta version can continue to add any source.

AltStore/Base.lproj/Main.storyboard

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17503.1" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="wKh-xq-NuP">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="20037" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="wKh-xq-NuP">
     <device id="retina4_7" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17502"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="20020"/>
         <capability name="Named colors" minToolsVersion="9.0"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
         <capability name="System colors in document resources" minToolsVersion="11.0"/>
@@ -314,8 +314,8 @@
                                                 </textView>
                                             </subviews>
                                             <constraints>
-                                                <constraint firstItem="Pyt-8D-BZA" firstAttribute="top" secondItem="D1G-nK-G0Z" secondAttribute="top" constant="20" id="Lm9-lx-kJ8"/>
+                                                <constraint firstItem="Pyt-8D-BZA" firstAttribute="top" secondItem="D1G-nK-G0Z" secondAttribute="top" priority="999" constant="20" id="Lm9-lx-kJ8"/>
-                                                <constraint firstAttribute="bottom" secondItem="Pyt-8D-BZA" secondAttribute="bottom" constant="44" id="TSS-Au-gYx"/>
+                                                <constraint firstAttribute="bottom" secondItem="Pyt-8D-BZA" secondAttribute="bottom" priority="999" constant="44" id="TSS-Au-gYx"/>
                                                 <constraint firstItem="Pyt-8D-BZA" firstAttribute="leading" secondItem="D1G-nK-G0Z" secondAttribute="leading" constant="20" id="UlS-ct-L9Y"/>
                                                 <constraint firstAttribute="trailing" secondItem="Pyt-8D-BZA" secondAttribute="trailing" constant="20" id="Wq4-Ql-wvN"/>
                                             </constraints>
@@ -944,15 +944,15 @@ World</string>
         <scene sceneID="0S1-zn-9KZ">
             <objects>
                 <collectionViewController title="Sources" id="cHC-TX-KzQ" customClass="SourcesViewController" customModule="AltStore" customModuleProvider="target" sceneMemberID="viewController">
-                    <collectionView key="view" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" preservesSuperviewLayoutMargins="YES" dataMode="prototypes" id="S36-hD-vu2">
+                    <collectionView key="view" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" preservesSuperviewLayoutMargins="YES" alwaysBounceVertical="YES" dataMode="prototypes" id="S36-hD-vu2">
                         <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <color key="backgroundColor" systemColor="systemBackgroundColor"/>
                         <collectionViewFlowLayout key="collectionViewLayout" minimumLineSpacing="15" minimumInteritemSpacing="10" id="X20-b5-XEP">
                             <size key="itemSize" width="375" height="80"/>
                             <size key="headerReferenceSize" width="50" height="200"/>
-                            <size key="footerReferenceSize" width="0.0" height="0.0"/>
+                            <size key="footerReferenceSize" width="50" height="50"/>
-                            <inset key="sectionInset" minX="0.0" minY="10" maxX="0.0" maxY="20"/>
+                            <inset key="sectionInset" minX="0.0" minY="0.0" maxX="0.0" maxY="0.0"/>
                         </collectionViewFlowLayout>
                         <cells>
                             <collectionViewCell opaque="NO" multipleTouchEnabled="YES" contentMode="center" preservesSuperviewLayoutMargins="YES" reuseIdentifier="Cell" id="XcN-o4-9qm" customClass="BannerCollectionViewCell" customModule="AltStore" customModuleProvider="target">
@@ -999,7 +999,46 @@ World</string>
                                 <constraint firstAttribute="leadingMargin" secondItem="TZv-TM-uJj" secondAttribute="leading" id="aS5-6Y-rMd"/>
                             </constraints>
                             <connections>
+                                <outlet property="bottomLayoutConstraint" destination="Aml-PC-dko" id="I1s-ae-C8A"/>
+                                <outlet property="leadingLayoutConstraint" destination="aS5-6Y-rMd" id="An8-KN-xfb"/>
                                 <outlet property="textLabel" destination="TZv-TM-uJj" id="kWV-Wv-5gz"/>
+                                <outlet property="topLayoutConstraint" destination="2zE-UV-24S" id="mjq-yH-v8J"/>
+                                <outlet property="trailingLayoutConstraint" destination="V0U-al-5eb" id="z8b-2G-SgY"/>
+                            </connections>
+                        </collectionReusableView>
+                        <collectionReusableView key="sectionFooterView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" insetsLayoutMarginsFromSafeArea="NO" reuseIdentifier="Footer" id="X5B-Kp-w1p" customClass="SourcesFooterView">
+                            <rect key="frame" x="0.0" y="280" width="375" height="50"/>
+                            <autoresizingMask key="autoresizingMask"/>
+                            <subviews>
+                                <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" spacing="15" translatesAutoresizingMaskIntoConstraints="NO" id="j0O-xE-gyd">
+                                    <rect key="frame" x="8" y="0.0" width="359" height="50"/>
+                                    <subviews>
+                                        <activityIndicatorView opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" hidesWhenStopped="YES" animating="YES" style="medium" translatesAutoresizingMaskIntoConstraints="NO" id="PNx-uR-y2F">
+                                            <rect key="frame" x="0.0" y="0.0" width="359" height="3"/>
+                                        </activityIndicatorView>
+                                        <textView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" verticalCompressionResistancePriority="800" scrollEnabled="NO" contentInsetAdjustmentBehavior="never" editable="NO" text="Test" textAlignment="natural" translatesAutoresizingMaskIntoConstraints="NO" id="66c-H8-KJx">
+                                            <rect key="frame" x="0.0" y="18" width="359" height="32"/>
+                                            <color key="backgroundColor" systemColor="systemBackgroundColor"/>
+                                            <color key="textColor" white="0.5" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+                                            <fontDescription key="fontDescription" style="UICTFontTextStyleSubhead"/>
+                                            <textInputTraits key="textInputTraits" autocapitalizationType="sentences"/>
+                                        </textView>
+                                    </subviews>
+                                </stackView>
+                            </subviews>
+                            <constraints>
+                                <constraint firstAttribute="bottom" secondItem="j0O-xE-gyd" secondAttribute="bottom" id="BQ5-11-BzK"/>
+                                <constraint firstItem="j0O-xE-gyd" firstAttribute="top" secondItem="X5B-Kp-w1p" secondAttribute="top" id="KZg-fd-8Cp" propertyAccessControl="none"/>
+                                <constraint firstItem="j0O-xE-gyd" firstAttribute="leading" secondItem="X5B-Kp-w1p" secondAttribute="leadingMargin" id="R2x-Io-bXD"/>
+                                <constraint firstAttribute="trailingMargin" secondItem="j0O-xE-gyd" secondAttribute="trailing" id="aBK-Bq-P9O"/>
+                            </constraints>
+                            <connections>
+                                <outlet property="activityIndicatorView" destination="PNx-uR-y2F" id="7Le-VW-GYK"/>
+                                <outlet property="bottomLayoutConstraint" destination="BQ5-11-BzK" id="iJR-4o-u9l"/>
+                                <outlet property="leadingLayoutConstraint" destination="R2x-Io-bXD" id="plZ-Yj-zTc"/>
+                                <outlet property="textView" destination="66c-H8-KJx" id="kwc-OH-U6i"/>
+                                <outlet property="topLayoutConstraint" destination="KZg-fd-8Cp" id="zNM-UU-feF"/>
+                                <outlet property="trailingLayoutConstraint" destination="aBK-Bq-P9O" id="L2r-VL-ruT"/>
                             </connections>
                         </collectionReusableView>
                         <connections>

AltStore/Components/TextCollectionReusableView.swift

@@ -11,4 +11,9 @@ import UIKit
 class TextCollectionReusableView: UICollectionReusableView
 {
     @IBOutlet var textLabel: UILabel!
+    
+    @IBOutlet var topLayoutConstraint: NSLayoutConstraint!
+    @IBOutlet var bottomLayoutConstraint: NSLayoutConstraint!
+    @IBOutlet var leadingLayoutConstraint: NSLayoutConstraint!
+    @IBOutlet var trailingLayoutConstraint: NSLayoutConstraint!
 }

AltStore/Managing Apps/AppManager.swift

@@ -312,9 +312,12 @@ extension AppManager
 
 extension AppManager
 {
-    func fetchSource(sourceURL: URL, completionHandler: @escaping (Result<Source, Error>) -> Void)
+    func fetchSource(sourceURL: URL,
+                     managedObjectContext: NSManagedObjectContext = DatabaseManager.shared.persistentContainer.newBackgroundContext(),
+                     dependencies: [Foundation.Operation] = [],
+                     completionHandler: @escaping (Result<Source, Error>) -> Void)
     {
-        let fetchSourceOperation = FetchSourceOperation(sourceURL: sourceURL)
+        let fetchSourceOperation = FetchSourceOperation(sourceURL: sourceURL, managedObjectContext: managedObjectContext)
         fetchSourceOperation.resultHandler = { (result) in
             switch result
             {
@@ -326,6 +329,11 @@ extension AppManager
             }
         }
         
+        for dependency in dependencies
+        {
+            fetchSourceOperation.addDependency(dependency)
+        }
+        
         self.run([fetchSourceOperation], context: nil)
     }
     

AltStore/Sources/SourcesViewController.swift

@@ -30,6 +30,22 @@ struct SourceError: LocalizedError
     }
 }
 
+@objc(SourcesFooterView)
+private class SourcesFooterView: TextCollectionReusableView
+{
+    @IBOutlet var activityIndicatorView: UIActivityIndicatorView!
+    @IBOutlet var textView: UITextView!
+}
+
+extension SourcesViewController
+{
+    private enum Section: Int, CaseIterable
+    {
+        case added
+        case trusted
+    }
+}
+
 class SourcesViewController: UICollectionViewController
 {
     var deepLinkSourceURL: URL? {
@@ -40,6 +56,12 @@ class SourcesViewController: UICollectionViewController
     }
     
     private lazy var dataSource = self.makeDataSource()
+    private lazy var addedSourcesDataSource = self.makeAddedSourcesDataSource()
+    private lazy var trustedSourcesDataSource = self.makeTrustedSourcesDataSource()
+    
+    private var fetchTrustedSourcesOperation: FetchTrustedSourcesOperation?
+    private var fetchTrustedSourcesResult: Result<Void, Error>?
+    private var _fetchTrustedSourcesContext: NSManagedObjectContext?
         
     override func viewDidLoad()
     {
@@ -61,6 +83,11 @@ class SourcesViewController: UICollectionViewController
         {
             self.navigationItem.leftBarButtonItem?.isIndicatingActivity = true
         }
+        
+        if self.fetchTrustedSourcesOperation == nil
+        {
+            self.fetchTrustedSources()
+        }
     }
     
     override func viewDidAppear(_ animated: Bool)
@@ -70,22 +97,15 @@ class SourcesViewController: UICollectionViewController
         if let sourceURL = self.deepLinkSourceURL
         {
             self.addSource(url: sourceURL)
-            self.deepLinkSourceURL = nil
         }
     }
 }
 
 private extension SourcesViewController
 {
-    func makeDataSource() -> RSTFetchedResultsCollectionViewDataSource<Source>
+    func makeDataSource() -> RSTCompositeCollectionViewDataSource<Source>
     {
-        let fetchRequest = Source.fetchRequest() as NSFetchRequest<Source>
+        let dataSource = RSTCompositeCollectionViewDataSource<Source>(dataSources: [self.addedSourcesDataSource, self.trustedSourcesDataSource])
-        fetchRequest.sortDescriptors = [NSSortDescriptor(keyPath: \Source.name, ascending: true),
-                                        NSSortDescriptor(keyPath: \Source.sourceURL, ascending: true),
-                                        NSSortDescriptor(keyPath: \Source.identifier, ascending: true)]
-        fetchRequest.returnsObjectsAsFaults = false
-        
-        let dataSource = RSTFetchedResultsCollectionViewDataSource<Source>(fetchRequest: fetchRequest, managedObjectContext: DatabaseManager.shared.viewContext)
         dataSource.proxy = self
         dataSource.cellConfigurationHandler = { (cell, source, indexPath) in
             let tintColor = UIColor.altPrimary
@@ -97,9 +117,44 @@ private extension SourcesViewController
                         
             cell.bannerView.iconImageView.isHidden = true
             cell.bannerView.buttonLabel.isHidden = true
-            cell.bannerView.button.isHidden = true
             cell.bannerView.button.isIndicatingActivity = false
             
+            switch Section.allCases[indexPath.section]
+            {
+            case .added:
+                cell.bannerView.button.isHidden = true
+                
+            case .trusted:
+                // Quicker way to determine whether a source is already added than by reading from disk.
+                if (self.addedSourcesDataSource.fetchedResultsController.fetchedObjects ?? []).contains(where: { $0.identifier == source.identifier })
+                {
+                    // Source exists in .added section, so hide the button.
+                    cell.bannerView.button.isHidden = true
+                    
+                    if #available(iOS 13.0, *)
+                    {
+                        let configuation = UIImage.SymbolConfiguration(pointSize: 24)
+                        
+                        let imageAttachment = NSTextAttachment()
+                        imageAttachment.image = UIImage(systemName: "checkmark.circle", withConfiguration: configuation)?.withTintColor(.altPrimary)
+
+                        let attributedText = NSAttributedString(attachment: imageAttachment)
+                        cell.bannerView.buttonLabel.attributedText = attributedText
+                        cell.bannerView.buttonLabel.textAlignment = .center
+                        cell.bannerView.buttonLabel.isHidden = false
+                    }
+                }
+                else
+                {
+                    // Source does not exist in .added section, so show the button.
+                    cell.bannerView.button.isHidden = false
+                    cell.bannerView.buttonLabel.attributedText = nil
+                }
+                
+                cell.bannerView.button.setTitle(NSLocalizedString("ADD", comment: ""), for: .normal)
+                cell.bannerView.button.addTarget(self, action: #selector(SourcesViewController.addTrustedSource(_:)), for: .primaryActionTriggered)
+            }
+                                                
             cell.bannerView.titleLabel.text = source.name
             cell.bannerView.subtitleLabel.text = source.sourceURL.absoluteString
             cell.bannerView.subtitleLabel.numberOfLines = 2
@@ -116,6 +171,24 @@ private extension SourcesViewController
         
         return dataSource
     }
+    
+    func makeAddedSourcesDataSource() -> RSTFetchedResultsCollectionViewDataSource<Source>
+    {
+        let fetchRequest = Source.fetchRequest() as NSFetchRequest<Source>
+        fetchRequest.returnsObjectsAsFaults = false
+        fetchRequest.sortDescriptors = [NSSortDescriptor(keyPath: \Source.name, ascending: true),
+                                        NSSortDescriptor(keyPath: \Source.sourceURL, ascending: true),
+                                        NSSortDescriptor(keyPath: \Source.identifier, ascending: true)]
+        
+        let dataSource = RSTFetchedResultsCollectionViewDataSource<Source>(fetchRequest: fetchRequest, managedObjectContext: DatabaseManager.shared.viewContext)
+        return dataSource
+    }
+    
+    func makeTrustedSourcesDataSource() -> RSTArrayCollectionViewDataSource<Source>
+    {
+        let dataSource = RSTArrayCollectionViewDataSource<Source>(items: [])
+        return dataSource
+    }
 }
 
 private extension SourcesViewController
@@ -135,31 +208,52 @@ private extension SourcesViewController
                 guard let httpsSourceURL = URL(string: "https://" + text) else { return }
                 sourceURL = httpsSourceURL
             }
-            self.addSource(url: sourceURL)
+            
+            self.navigationItem.leftBarButtonItem?.isIndicatingActivity = true
+            
+            self.addSource(url: sourceURL) { _ in
+                self.navigationItem.leftBarButtonItem?.isIndicatingActivity = false
+            }
         })
         
         self.present(alertController, animated: true, completion: nil)
     }
     
-    func addSource(url: URL)
+    func addSource(url: URL, isTrusted: Bool = false, completionHandler: ((Result<Void, Error>) -> Void)? = nil)
     {
         guard self.view.window != nil else { return }
         
-        self.navigationItem.leftBarButtonItem?.isIndicatingActivity = true
+        if url == self.deepLinkSourceURL
+        {
+            // Only handle deep link once.
+            self.deepLinkSourceURL = nil
+        }
         
-        func finish(error: Error?)
+        func finish(_ result: Result<Void, Error>)
         {
             DispatchQueue.main.async {
-                if let error = error
+                switch result
                 {
-                    self.present(error)
+                case .success: break
+                case .failure(OperationError.cancelled): break
+                case .failure(let error): self.present(error)
                 }
                 
-                self.navigationItem.leftBarButtonItem?.isIndicatingActivity = false
+                self.collectionView.reloadSections([Section.trusted.rawValue])
+                
+                completionHandler?(result)
             }
         }
         
-        AppManager.shared.fetchSource(sourceURL: url) { (result) in
+        var dependencies: [Foundation.Operation] = []
+        if let fetchTrustedSourcesOperation = self.fetchTrustedSourcesOperation
+        {
+            // Must fetch trusted sources first to determine whether this is a trusted source.
+            // We assume fetchTrustedSources() has already been called before this method.
+            dependencies = [fetchTrustedSourcesOperation]
+        }
+        
+        AppManager.shared.fetchSource(sourceURL: url, dependencies: dependencies) { (result) in
             do
             {
                 let source = try result.get()
@@ -167,25 +261,28 @@ private extension SourcesViewController
                 let managedObjectContext = source.managedObjectContext
                 
                 #if !BETA
-                guard Source.allowedIdentifiers.contains(source.identifier) else { throw SourceError(code: .unsupported, source: source) }
+                guard let trustedSourceIDs = UserDefaults.shared.trustedSourceIDs, trustedSourceIDs.contains(source.identifier) else { throw SourceError(code: .unsupported, source: source) }
                 #endif
                 
+                // Hide warning when adding a featured trusted source.
+                let message = isTrusted ? nil : NSLocalizedString("Make sure to only add sources that you trust.", comment: "")
+                
                 DispatchQueue.main.async {
                     let alertController = UIAlertController(title: String(format: NSLocalizedString("Would you like to add the source “%@”?", comment: ""), sourceName),
-                                                            message: NSLocalizedString("Sources control what apps appear in AltStore. Make sure to only add sources that you trust.", comment: ""), preferredStyle: .alert)
+                                                            message: message, preferredStyle: .alert)
                     alertController.addAction(UIAlertAction(title: UIAlertAction.cancel.title, style: UIAlertAction.cancel.style) { _ in
-                        finish(error: nil)
+                        finish(.failure(OperationError.cancelled))
                     })
-                    alertController.addAction(UIAlertAction(title: UIAlertAction.ok.title, style: UIAlertAction.ok.style) { _ in
+                    alertController.addAction(UIAlertAction(title: NSLocalizedString("Add Source", comment: ""), style: UIAlertAction.ok.style) { _ in
                         managedObjectContext?.perform {
                             do
                             {
                                 try managedObjectContext?.save()
-                                finish(error: nil)
+                                finish(.success(()))
                             }
                             catch
                             {
-                                finish(error: error)
+                                finish(.failure(error))
                             }
                         }
                     })
@@ -194,7 +291,7 @@ private extension SourcesViewController
             }
             catch
             {
-                finish(error: error)
+                finish(.failure(error))
             }
         }
     }
@@ -217,6 +314,130 @@ private extension SourcesViewController
         alertController.addAction(.ok)
         self.present(alertController, animated: true, completion: nil)
     }
+    
+    func fetchTrustedSources()
+    {
+        func finish(_ result: Result<[Source], Error>)
+        {
+            self.fetchTrustedSourcesResult = result.map { _ in () }
+            
+            DispatchQueue.main.async {
+                do
+                {
+                    let sources = try result.get()
+                    print("Fetched trusted sources:", sources.map { $0.identifier })
+
+                    let sectionUpdate = RSTCellContentChange(type: .update, sectionIndex: 0)
+                    self.trustedSourcesDataSource.setItems(sources, with: [sectionUpdate])
+                }
+                catch
+                {
+                    print("Error fetching trusted sources:", error)
+                    
+                    let sectionUpdate = RSTCellContentChange(type: .update, sectionIndex: 0)
+                    self.trustedSourcesDataSource.setItems([], with: [sectionUpdate])
+                }
+            }
+        }
+        
+        self.fetchTrustedSourcesOperation = AppManager.shared.fetchTrustedSources { result in
+            switch result
+            {
+            case .failure(let error): finish(.failure(error))
+            case .success(let trustedSources):
+                // Cache trusted source IDs.
+                UserDefaults.shared.trustedSourceIDs = trustedSources.map { $0.identifier }
+                
+                // Don't show sources without a sourceURL.
+                let featuredSourceURLs = trustedSources.compactMap { $0.sourceURL }
+                
+                // This context is never saved, but keeps the managed sources alive.
+                let context = DatabaseManager.shared.persistentContainer.newBackgroundSavingViewContext()
+                self._fetchTrustedSourcesContext = context
+                
+                let dispatchGroup = DispatchGroup()
+                
+                var sourcesByURL = [URL: Source]()
+                var fetchError: Error?
+                
+                for sourceURL in featuredSourceURLs
+                {
+                    dispatchGroup.enter()
+                    
+                    AppManager.shared.fetchSource(sourceURL: sourceURL, managedObjectContext: context) { result in
+                        // Serialize access to sourcesByURL.
+                        context.performAndWait {
+                            switch result
+                            {
+                            case .failure(let error): fetchError = error
+                            case .success(let source): sourcesByURL[source.sourceURL] = source
+                            }
+                            
+                            dispatchGroup.leave()
+                        }
+                    }
+                }
+                
+                dispatchGroup.notify(queue: .main) {
+                    if let error = fetchError
+                    {
+                        finish(.failure(error))
+                    }
+                    else
+                    {
+                        let sources = featuredSourceURLs.compactMap { sourcesByURL[$0] }
+                        finish(.success(sources))
+                    }
+                }
+            }
+        }
+    }
+    
+    @IBAction func addTrustedSource(_ sender: PillButton)
+    {
+        let point = self.collectionView.convert(sender.center, from: sender.superview)
+        guard let indexPath = self.collectionView.indexPathForItem(at: point) else { return }
+        
+        let completedProgress = Progress(totalUnitCount: 1)
+        completedProgress.completedUnitCount = 1
+        sender.progress = completedProgress
+        
+        let source = self.dataSource.item(at: indexPath)
+        self.addSource(url: source.sourceURL, isTrusted: true) { _ in
+            //FIXME: Handle cell reuse.
+            sender.progress = nil
+        }
+    }
+    
+    func remove(_ source: Source)
+    {
+        let alertController = UIAlertController(title: String(format: NSLocalizedString("Are you sure you want to remove the source “%@”?", comment: ""), source.name),
+                                                message: NSLocalizedString("Any apps you've installed from this source will remain, but they'll no longer receive any app updates.", comment: ""), preferredStyle: .alert)
+        alertController.addAction(UIAlertAction(title: UIAlertAction.cancel.title, style: UIAlertAction.cancel.style, handler: nil))
+        alertController.addAction(UIAlertAction(title: NSLocalizedString("Remove Source", comment: ""), style: .destructive) { _ in
+            DatabaseManager.shared.persistentContainer.performBackgroundTask { (context) in
+                let source = context.object(with: source.objectID) as! Source
+                context.delete(source)
+                
+                do
+                {
+                    try context.save()
+                    
+                    DispatchQueue.main.async {
+                        self.collectionView.reloadSections([Section.trusted.rawValue])
+                    }
+                }
+                catch
+                {
+                    DispatchQueue.main.async {
+                        self.present(error)
+                    }
+                }
+            }
+        })
+        
+        self.present(alertController, animated: true, completion: nil)
+    }
 }
 
 extension SourcesViewController
@@ -251,11 +472,112 @@ extension SourcesViewController: UICollectionViewDelegateFlowLayout
         return size
     }
     
+    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize
+    {
+        guard Section(rawValue: section) == .trusted else { return .zero }
+        
+        let indexPath = IndexPath(row: 0, section: section)
+        let headerView = self.collectionView(collectionView, viewForSupplementaryElementOfKind: UICollectionView.elementKindSectionFooter, at: indexPath)
+        
+        // Use this view to calculate the optimal size based on the collection view's width
+        let size = headerView.systemLayoutSizeFitting(CGSize(width: collectionView.frame.width, height: UIView.layoutFittingExpandedSize.height),
+                                                      withHorizontalFittingPriority: .required, // Width is fixed
+                                                      verticalFittingPriority: .fittingSizeLevel) // Height can be as large as needed
+        return size
+    }
+    
     override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView
     {
-        let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "Header", for: indexPath) as! TextCollectionReusableView
+        let reuseIdentifier = (kind == UICollectionView.elementKindSectionHeader) ? "Header" : "Footer"
+        
+        let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: reuseIdentifier, for: indexPath) as! TextCollectionReusableView
         headerView.layoutMargins.left = self.view.layoutMargins.left
         headerView.layoutMargins.right = self.view.layoutMargins.right
+        
+        let almostRequiredPriority = UILayoutPriority(UILayoutPriority.required.rawValue - 1) // Can't be required or else we can't satisfy constraints when hidden (size = 0).
+        headerView.leadingLayoutConstraint?.priority = almostRequiredPriority
+        headerView.trailingLayoutConstraint?.priority = almostRequiredPriority
+        headerView.topLayoutConstraint?.priority = almostRequiredPriority
+        headerView.bottomLayoutConstraint?.priority = almostRequiredPriority
+        
+        switch kind
+        {
+        case UICollectionView.elementKindSectionHeader:
+            switch Section.allCases[indexPath.section]
+            {
+            case .added:
+                headerView.textLabel.text = NSLocalizedString("Sources control what apps are available to download through AltStore.", comment: "")
+                headerView.textLabel.font = UIFont.preferredFont(forTextStyle: .callout)
+                headerView.textLabel.textAlignment = .natural
+                
+                headerView.topLayoutConstraint.constant = 14
+                headerView.bottomLayoutConstraint.constant = 30
+                
+            case .trusted:
+                switch self.fetchTrustedSourcesResult
+                {
+                case .failure: headerView.textLabel.text = NSLocalizedString("Error Loading Trusted Sources", comment: "")
+                case .success, .none: headerView.textLabel.text = NSLocalizedString("Trusted Sources", comment: "")
+                }
+                
+                let descriptor = UIFontDescriptor.preferredFontDescriptor(withTextStyle: .callout).withSymbolicTraits(.traitBold)!
+                headerView.textLabel.font = UIFont(descriptor: descriptor, size: 0)
+                headerView.textLabel.textAlignment = .center
+                
+                headerView.topLayoutConstraint.constant = 54
+                headerView.bottomLayoutConstraint.constant = 15
+            }
+            
+        case UICollectionView.elementKindSectionFooter:
+            let footerView = headerView as! SourcesFooterView
+            let font = UIFont.preferredFont(forTextStyle: .subheadline)
+            
+            switch self.fetchTrustedSourcesResult
+            {
+            case .failure(let error):
+                footerView.textView.font = font
+                footerView.textView.text = error.localizedDescription
+                
+                footerView.activityIndicatorView.stopAnimating()
+                footerView.topLayoutConstraint.constant = 0
+                footerView.textView.textAlignment = .center
+                
+            case .success, .none:
+                footerView.textView.delegate = self
+                
+                let attributedText = NSMutableAttributedString(
+                    string: NSLocalizedString("AltStore has reviewed these sources to make sure they meet our safety standards.\n\nSupport for untrusted sources is currently in beta, but you can help test them out by", comment: ""),
+                    attributes: [.font: font, .foregroundColor: UIColor.gray]
+                )
+                attributedText.mutableString.append(" ")
+                
+                let boldedFont = UIFont(descriptor: font.fontDescriptor.withSymbolicTraits(.traitBold)!, size: font.pointSize)
+                let openPatreonURL = URL(string: "https://altstore.io/patreon")!
+                
+                let joinPatreonText = NSAttributedString(
+                    string: NSLocalizedString("joining our Patreon.", comment: ""),
+                    attributes: [.font: boldedFont, .link: openPatreonURL, .underlineColor: UIColor.clear]
+                )
+                attributedText.append(joinPatreonText)
+                
+                footerView.textView.attributedText = attributedText
+                footerView.textView.textAlignment = .natural
+                
+                if self.fetchTrustedSourcesResult != nil
+                {
+                    footerView.activityIndicatorView.stopAnimating()
+                    footerView.topLayoutConstraint.constant = 20
+                }
+                else
+                {
+                    footerView.activityIndicatorView.startAnimating()
+                    footerView.topLayoutConstraint.constant = 0
+                }
+            }
+            
+        default: break
+        }
+                
         return headerView
     }
 }
@@ -274,20 +596,11 @@ extension SourcesViewController
             }
             
             let deleteAction = UIAction(title: NSLocalizedString("Remove", comment: ""), image: UIImage(systemName: "trash"), attributes: [.destructive]) { (action) in
+                self.remove(source)
+            }
             
-                DatabaseManager.shared.persistentContainer.performBackgroundTask { (context) in
+            let addAction = UIAction(title: String(format: NSLocalizedString("Add “%@”", comment: ""), source.name), image: UIImage(systemName: "plus")) { (action) in
-                    let source = context.object(with: source.objectID) as! Source
+                self.addSource(url: source.sourceURL, isTrusted: true)
-                    context.delete(source)
-                    
-                    do
-                    {
-                        try context.save()
-                    }
-                    catch
-                    {
-                        print("Failed to save source context.", error)
-                    }
-                }
             }
             
             var actions: [UIAction] = []
@@ -297,11 +610,23 @@ extension SourcesViewController
                 actions.append(viewErrorAction)
             }
             
-            if source.identifier != Source.altStoreIdentifier
+            switch Section.allCases[indexPath.section]
             {
-                actions.append(deleteAction)
+            case .added:
+                if source.identifier != Source.altStoreIdentifier
+                {
+                    actions.append(deleteAction)
+                }
+                
+            case .trusted:
+                if let cell = collectionView.cellForItem(at: indexPath) as? BannerCollectionViewCell, !cell.bannerView.button.isHidden
+                {
+                    actions.append(addAction)
+                }
             }
             
+            guard !actions.isEmpty else { return nil }
+            
             let menu = UIMenu(title: "", children: actions)
             return menu
         }
@@ -325,3 +650,11 @@ extension SourcesViewController
         return self.collectionView(collectionView, previewForHighlightingContextMenuWithConfiguration: configuration)
     }
 }
+
+extension SourcesViewController: UITextViewDelegate
+{
+    func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool
+    {
+        return true
+    }
+}

AltStoreCore/Extensions/UserDefaults+AltStore.swift

@@ -37,6 +37,8 @@ public extension UserDefaults
     
     @NSManaged var patchedApps: [String]?
     
+    @NSManaged var trustedSourceIDs: [String]?
+    
     var activeAppsLimit: Int? {
         get {
             return self._activeAppsLimit?.intValue

AltStoreCore/Model/Source.swift

@@ -33,10 +33,6 @@ public extension Source
     #endif
     
     #endif
-    
-    static let exampleIdentifier = "io.altstore.example"
-    
-    static let allowedIdentifiers: Set<String> = [exampleIdentifier]
 }
 
 @objc(Source)