Firebase 应用程序在从后台激活时在启动时崩溃
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【中文标题】Firebase 应用程序在从后台激活时在启动时崩溃【英文标题】：Firebase App crashed on launch when made active from background 【发布时间】：2019-05-27 11:13:10 【问题描述】：我的 swift 应用程序中集成了一个 Firebase。所有的初始化都是以编程方式完成的，FirebaseApp.config() 在 AppDelegate 的didLaunchWithOptions 中被称为第一件事。
但由于某种随机原因，每当应用程序长时间处于后台时，应用程序就会在运行时崩溃，即使其处于活动状态。 有趣的是，这种崩溃在以下流程中恰好发生了 2 次：
1. The App is idle in background
2. You bring it to the active mode(You just tap the icon to open the app. All this while the app isn't killed)
3. Tap 1 ---- The App Crashes----
4. Tap 2 ---- The App Crashes----
5. Tap 3 ---- The App Runs Normally ----
我试图排除故障，但我所有的努力都白费了。我尝试设置故事板和以编程方式启动应用程序。没有任何效果。
以下是堆栈跟踪：
SpotMi-Dev[74741:2958059] *** Terminating app due to uncaught exception 'FIRAppNotConfigured', reason: 'Failed to get default Firebase Database instance. Must call `[FIRApp configure]` (`FirebaseApp.configure()` in Swift) before using Firebase Database.'
*** First throw call stack:
(
0 CoreFoundation 0x000000010d3816fb __exceptionPreprocess + 331
1 libobjc.A.dylib 0x000000010c14aac5 objc_exception_throw + 48
2 CoreFoundation 0x000000010d381555 +[NSException raise:format:] + 197
3 SpotMi-Dev 0x0000000101be5ba1 +[FIRDatabase database] + 97
4 SpotMi-Dev 0x0000000101aaba6b $s10SpotMi_Dev13FBDataserviceCACycfc + 59
5 SpotMi-Dev 0x0000000101aac193 $s10SpotMi_Dev13FBDataserviceCACycfcTo + 19
6 SpotMi-Dev 0x0000000101aa696c $s10SpotMi_Dev13FBDataserviceCACycfC + 44
7 SpotMi-Dev 0x0000000101aa692c globalinit_33_8263DB418F9D5BC81149F56895386F46_func0 + 28
8 libdispatch.dylib 0x000000010ecaddb5 _dispatch_client_callout + 8
9 libdispatch.dylib 0x000000010ecaf83d _dispatch_once_callout + 66
10 libswiftCore.dylib 0x000000010e2c6579 swift_once + 25
11 SpotMi-Dev 0x0000000101aa69f4 $s10SpotMi_Dev13FBDataserviceC2dsACvau + 36
12 SpotMi-Dev 0x000000010180b013 $s10SpotMi_Dev9ProfileVCC18initializeUserPostyyF + 179
13 SpotMi-Dev 0x0000000101809278 $s10SpotMi_Dev9ProfileVCC11viewDidLoadyyF + 616
14 SpotMi-Dev 0x00000001018095b4 $s10SpotMi_Dev9ProfileVCC11viewDidLoadyyFTo + 36
15 UIKitCore 0x000000011589443b -[UIViewController loadViewIfRequired] + 1183
16 UIKitCore 0x0000000115894868 -[UIViewController view] + 27
17 UIKitCore 0x0000000115ebd4ad -[UIApplication(StateRestoration) _restoreApplicationPreservationStateWithSessionIdentifier:beginHandler:completionHandler:] + 6413
18 UIKitCore 0x0000000115eb8fdc -[UIApplication(StateRestoration) _doRestorationIfNecessary] + 211
19 UIKitCore 0x0000000115e8e2c9 -[UIApplication _handleDelegateCallbacksWithOptions:isSuspended:restoreState:] + 208
20 UIKitCore 0x0000000115e8fcad -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 3932
21 UIKitCore 0x0000000115e950c6 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1617
22 UIKitCore 0x00000001156da6d6 __111-[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:]_block_invoke + 904
23 UIKitCore 0x00000001156e2fce +[_UICanvas _enqueuePostSettingUpdateTransactionBlock:] + 153
24 UIKitCore 0x00000001156da2ec -[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:] + 236
25 UIKitCore 0x00000001156dac48 -[__UICanvasLifecycleMonitor_Compatability activateEventsOnly:withContext:completion:] + 1091
26 UIKitCore 0x00000001156d8fba __82-[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:]_block_invoke + 782
27 UIKitCore 0x00000001156d8c71 -[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:] + 433
28 UIKitCore 0x00000001156dd9b6 __125-[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]_block_invoke + 576
29 UIKitCore 0x00000001156de610 _performActionsWithDelayForTransitionContext + 100
30 UIKitCore 0x00000001156dd71d -[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:] + 223
31 UIKitCore 0x00000001156e26d0 -[_UICanvas scene:didUpdateWithDiff:transitionContext:completion:] + 392
32 UIKitCore 0x0000000115e939a8 -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 514
33 UIKitCore 0x0000000115a4adfa -[UIApplicationSceneClientAgent scene:didInitializeWithEvent:completion:] + 361
34 FrontBoardServices 0x00000001133a4125 -[FBSSceneImpl _didCreateWithTransitionContext:completion:] + 448
35 FrontBoardServices 0x00000001133aded6 __56-[FBSWorkspace client:handleCreateScene:withCompletion:]_block_invoke_2 + 283
36 FrontBoardServices 0x00000001133ad700 __40-[FBSWorkspace _performDelegateCallOut:]_block_invoke + 53
37 libdispatch.dylib 0x000000010ecaddb5 _dispatch_client_callout + 8
38 libdispatch.dylib 0x000000010ecb12ba _dispatch_block_invoke_direct + 300
39 FrontBoardServices 0x00000001133df146 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 30
40 FrontBoardServices 0x00000001133dedfe -[FBSSerialQueue _performNext] + 451
41 FrontBoardServices 0x00000001133df393 -[FBSSerialQueue _performNextFromRunLoopSource] + 42
42 CoreFoundation 0x000000010d2e8be1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
43 CoreFoundation 0x000000010d2e8463 __CFRunLoopDoSources0 + 243
44 CoreFoundation 0x000000010d2e2b1f __CFRunLoopRun + 1231
45 CoreFoundation 0x000000010d2e2302 CFRunLoopRunSpecific + 626
46 GraphicsServices 0x000000011034e2fe GSEventRunModal + 65
47 UIKitCore 0x0000000115e96ba2 UIApplicationMain + 140
48 SpotMi-Dev 0x000000010174287b main + 75
49 libdyld.dylib 0x000000010ed22541 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
以下是来自 didLaunchWithOptions 的代码：
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool
#if DEVELOPMENT
print("Development Mode Started")
#else
print("Production Mode Started")
#endif
FirebaseApp.configure()
Messaging.messaging().delegate = self
//other app functions
return true
我在 init 控制器的 viewDidLoad 中调用 Firebase API。这是调用它的服务，这甚至包含崩溃。
class FBDataservice : NSObject
static var ds = FBDataservice() //<------ Creates Error here on every single crash related to this issue
let DB_URL: DatabaseReference = Database.database().reference()
let ST_URL: StorageReference = Storage.storage().reference()
private lazy var _REF_BASE = DB_URL
然后我只需在 viewDidLoad 或 viewDidAppear 中调用 FBDataservice.ds._REF_BASE.child("something").observe( .Event, with (Datasnapshot))。我主要是在获取数据。然后推送数据，比如在 AppDelegate 中的 didBecameActive 上更新 app RunCounts
我们将不胜感激任何帮助。干杯
【问题讨论】：
评论不适用于扩展讨论或调试会话；这个对话是archived in chat。 【参考方案1】：检查FirebaseApp.app()，如果这是nil，你能再打电话给FirebaseApp.configure()吗？如果这在appDidBecomeActive: 或didEneterInForeground: 方法中崩溃，您需要调试。
另外请检查您在启动应用程序后第一次使用FirebaseDatabase 的位置（除了配置行）？我的意思是在任何ViewController 或任何地方，我们需要在这里检查条件。
更新问题：
关于您更新的问题FBDataservice()，您在哪里创建它的实例，因为当您创建它的实例时，它将创建与 Firebase 相关的 DB_URL 和 ST_URL url 实例，因此在此之前可能未配置 Firebase。你可以重写它的init方法来检查Firebase是否被配置。
当您创建此类的实例时，您将在构造函数中创建两个变量。
尝试一件事...替换
static var ds = FBDataservice()
与
static var ds: FBDataservice
if FirebaseApp.app() == nil
FirebaseApp.configure()
return FBDataservice()
【讨论】：
嘿，我刚刚遇到另一个错误。Terminating app due to uncaught exception 'com.firebase.core', reason: 'Default app has already been configured.'我想因为 Config 在 didFinishWithLaunch 中被调用两次，然后在实例中。您建议删除 appdelegate 中的那个吗？
我刚刚在委托中添加了相同的 FirebaseApp.app() 检查。所以解决了。但是你还有什么建议吗？
尝试在AppDelegate 中也加入相同的条件。 if FirebaseApp.app() == nil FirebaseApp.configure() 以上是关于Firebase 应用程序在从后台激活时在启动时崩溃的主要内容，如果未能解决你的问题，请参考以下文章
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