我只有iOS14的特定崩溃。我的代码很长一段时间没有改变，在所有以前版本的iOS上都没有问题，但根据Crashlytics的说法，我看到了这个堆栈：
Crashed: com.apple.main-thread
0 libdispatch.dylib 0x19125b7f4 <redacted> + 36
1 libdispatch.dylib 0x1912298c4 dispatch_group_leave + 126
2 MyApp 0x104e2c72c partial apply for closure #1 in AppDelegate.application(_:didReceiveRemoteNotification:fetchCompletionHandler:) + 4375054124 (<compiler-generated>:4375054124)
3 MyApp 0x104e2b488 closure #1 in closure #2 in AppDelegate.configureNotificationReceipt(userInfo:completionHandler:) + 194 (AppDelegate.swift:194)
4 MyApp 0x104e48d78 closure #1 in closure #1 in static AWSController.downloadFile(with:completion:) + 37 (AWSController.swift:37)
5 MyApp 0x104e5d794 thunk for @escaping @callee_guaranteed () -> () + 4375254932 (<compiler-generated>:4375254932)
6 libdispatch.dylib 0x191226fd0 <redacted> + 32
7 libdispatch.dylib 0x191228ac8 <redacted> + 20
8 libdispatch.dylib 0x19123604c _dispatch_main_queue_callback_4CF + 836
9 CoreFoundation 0x1915a71e4 <redacted> + 16
10 CoreFoundation 0x1915a13b4 <redacted> + 2508
11 CoreFoundation 0x1915a04bc CFRunLoopRunSpecific + 600
12 GraphicsServices 0x1a8025820 GSEventRunModal + 164
13 UIKitCore 0x193f44734 <redacted> + 1072
14 UIKitCore 0x193f49e10 UIApplicationMain + 168
15 MyApp 0x104e16e30 main + 17 (AppCoordinator.swift:17)
16 libdyld.dylib 0x191267e60 <redacted> + 4
还有来自Crashlytics的信息：
BUG IN CLIENT OF LIBDISPATCH: Unbalanced call to dispatch_group_leave()
我使用Firebase/Messaging进行通知。还有一个处理通知的代码：
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
configureNotificationReceipt(userInfo: userInfo) { (result) in
completionHandler(result)
}
}
正如我所写的，这次崩溃只适用于iOS14，以前从未发生过。如果我们谈论Unbalanced call to dispatch_group_leave()，我会说它可能与iOS的内部逻辑有关，因为我在任何地方都没有明确地使用GCD。
也许有人已经遇到了同样的行为，可以提出任何解决方法吗？
我认为是Firebase iOS SDK问题，该问题已在7.1.0版本上修复。
请参阅链接：
- https://github.com/firebase/firebase-ios-sdk/pull/6863
- https://firebase.google.com/support/release-notes/ios#7.1.0