Improves error handling when fetching multiple sources

Fetching sources is no longer all or nothing. Now if a source cannot be fetched, it won’t prevent other sources from being updated.

AltStore/Managing Apps/AppManager.swift

@@ -197,15 +197,16 @@ extension AppManager
         self.run([fetchSourceOperation], context: nil)
     }
     
-    func fetchSources(completionHandler: @escaping (Result<Set<Source>, Error>) -> Void)
+    func fetchSources(completionHandler: @escaping (Result<(Set<Source>, NSManagedObjectContext), FetchSourcesError>) -> Void)
     {
         DatabaseManager.shared.persistentContainer.performBackgroundTask { (context) in
             let sources = Source.all(in: context)
-            guard !sources.isEmpty else { return completionHandler(.failure(OperationError.noSources)) }
+            guard !sources.isEmpty else { return completionHandler(.failure(.init(OperationError.noSources))) }
             
             let dispatchGroup = DispatchGroup()
             var fetchedSources = Set<Source>()
-            var error: Error?
+            
+            var errors = [Source: Error]()
             
             let managedObjectContext = DatabaseManager.shared.persistentContainer.newBackgroundContext()
             
@@ -216,8 +217,10 @@ extension AppManager
                 fetchSourceOperation.resultHandler = { (result) in
                     switch result
                     {
-                    case .failure(let e): error = e
                     case .success(let source): fetchedSources.insert(source)
+                    case .failure(let error):
+                        let source = managedObjectContext.object(with: source.objectID) as! Source
+                        errors[source] = error
                     }
                     
                     dispatchGroup.leave()
@@ -227,14 +230,15 @@ extension AppManager
             }
             
             dispatchGroup.notify(queue: .global()) {
-                if let error = error
-                {
-                    completionHandler(.failure(error))
-                }
-                else
-                {
-                    managedObjectContext.perform {
-                        completionHandler(.success(fetchedSources))
+                managedObjectContext.perform {
+                    if !errors.isEmpty
+                    {
+                        let sources = Set(sources.compactMap { managedObjectContext.object(with: $0.objectID) as? Source })
+                        completionHandler(.failure(.init(sources: sources, errors: errors, context: managedObjectContext)))
+                    }
+                    else
+                    {
+                        completionHandler(.success((fetchedSources, managedObjectContext)))
                     }
                 }
                 

AltStore/Managing Apps/AppManagerErrors.swift

@@ -0,0 +1,84 @@
+//
+//  AppManagerErrors.swift
+//  AltStore
+//
+//  Created by Riley Testut on 8/27/20.
+//  Copyright © 2020 Riley Testut. All rights reserved.
+//
+
+import Foundation
+import CoreData
+
+extension AppManager
+{
+    struct FetchSourcesError: LocalizedError, CustomNSError
+    {
+        var primaryError: Error?
+        
+        var sources: Set<Source>?
+        var errors = [Source: Error]()
+        
+        var managedObjectContext: NSManagedObjectContext?
+        
+        var errorDescription: String? {
+            if let error = self.primaryError
+            {
+                return error.localizedDescription
+            }
+            else
+            {
+                var localizedDescription: String?
+                
+                self.managedObjectContext?.performAndWait {
+                    if self.sources?.count == 1
+                    {
+                        localizedDescription = NSLocalizedString("Could not refresh store.", comment: "")
+                    }
+                    else if self.errors.count == 1
+                    {
+                        guard let source = self.errors.keys.first else { return }
+                        localizedDescription = String(format: NSLocalizedString("Could not refresh source “%@”.", comment: ""), source.name)
+                    }
+                    else
+                    {
+                        localizedDescription = String(format: NSLocalizedString("Could not refresh %@ sources.", comment: ""), NSNumber(value: self.errors.count))
+                    }
+                }
+                
+                return localizedDescription
+            }
+        }
+        
+        var recoverySuggestion: String? {
+            if let error = self.primaryError as NSError?
+            {
+                return error.localizedRecoverySuggestion
+            }
+            else if self.errors.count == 1
+            {
+                return nil
+            }
+            else
+            {
+                return NSLocalizedString("Tap to view source errors.", comment: "")
+            }
+        }
+        
+        var errorUserInfo: [String : Any] {
+            guard let error = self.errors.values.first, self.errors.count == 1 else { return [:] }
+            return [NSUnderlyingErrorKey: error]
+        }
+        
+        init(_ error: Error)
+        {
+            self.primaryError = error
+        }
+        
+        init(sources: Set<Source>, errors: [Source: Error], context: NSManagedObjectContext)
+        {
+            self.sources = sources
+            self.errors = errors
+            self.managedObjectContext = context
+        }
+    }
+}