Refreshes apps by installing provisioning profiles when possible

Assuming the certificate used to originally sign an app is still valid, we can refresh an app simply by installing new provisioning profiles. However, if the signing certificate is no longer valid, we fall back to the old method of resigning + reinstalling.

AltStore/Operations/RefreshGroup.swift

@@ -0,0 +1,77 @@
+//
+//  RefreshGroup.swift
+//  AltStore
+//
+//  Created by Riley Testut on 6/20/19.
+//  Copyright © 2019 Riley Testut. All rights reserved.
+//
+
+import Foundation
+import CoreData
+
+import AltSign
+
+class RefreshGroup: NSObject
+{
+    let context: AuthenticatedOperationContext
+    let progress = Progress.discreteProgress(totalUnitCount: 0)
+    
+    var completionHandler: (([String: Result<InstalledApp, Error>]) -> Void)?
+    var beginInstallationHandler: ((InstalledApp) -> Void)?
+        
+    private(set) var results = [String: Result<InstalledApp, Error>]()
+    
+    private var isFinished = false
+    
+    private let dispatchGroup = DispatchGroup()
+    private var operations: [Foundation.Operation] = []
+    
+    init(context: AuthenticatedOperationContext = AuthenticatedOperationContext())
+    {
+        self.context = context
+        
+        super.init()
+    }
+    
+    func add(_ operations: [Foundation.Operation])
+    {
+        for operation in operations
+        {
+            self.dispatchGroup.enter()
+            
+            operation.completionBlock = { [weak self] in
+                self?.dispatchGroup.leave()
+            }
+        }
+        
+        if self.operations.isEmpty && !operations.isEmpty
+        {
+            self.dispatchGroup.notify(queue: .global()) {
+                self.finish()
+            }
+        }
+        
+        self.operations.append(contentsOf: operations)
+    }
+    
+    func set(_ result: Result<InstalledApp, Error>, forAppWithBundleIdentifier bundleIdentifier: String)
+    {
+        self.results[bundleIdentifier] = result
+    }
+    
+    func cancel()
+    {
+        self.operations.forEach { $0.cancel() }
+    }
+}
+
+private extension RefreshGroup
+{
+    func finish()
+    {
+        guard !self.isFinished else { return }
+        self.isFinished = true
+        
+        self.completionHandler?(self.results)
+    }
+}