我有一个用于iOS的自定义键盘，使用Firebase进行分析。 Firebase应用程序配置在初始化器中使用dispatch_once子句完成，并将令牌作为全局变量。
var token: dispatch_once_t = 0
class KeyboardViewController: UIInputViewController {
// ..
override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
dispatch_once(&token) {
FIRApp.configure()
} // line 90
}
// ..
}
这个功能本身是正常工作的，但是我收到了很多崩溃报告，显示许多设备在配置应用程序时发生了崩溃。我已经卡住了好几天，试图找出原因。以下是其中一个崩溃报告的部分堆栈跟踪：
Exception Type: EXC_CRASH (SIGQUIT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Termination Signal: Quit: 3
Termination Reason: Namespace SIGNAL, Code 0x3
Terminating Process: launchd [1]
Triggered by Thread: 0
Thread 0 name:
Thread 0 Crashed:
0 libsystem_kernel.dylib 0x000000018fab6338 __semwait_signal_nocancel + 8
1 libsystem_c.dylib 0x000000018f9e20dc nanosleep$NOCANCEL + 200 (nanosleep.c:104)
2 libsystem_c.dylib 0x000000018fa0568c sleep$NOCANCEL + 44 (sleep.c:62)
3 libsystem_dnssd.dylib 0x000000018fa6e7d4 ConnectToServer + 832 (dnssd_clientstub.c:607)
4 libsystem_dnssd.dylib 0x000000018fa6ff44 DNSServiceCreateConnection + 76 (dnssd_clientstub.c:1785)
5 libsystem_network.dylib 0x000000018fb2d318 __nw_resolver_set_update_handler_block_invoke + 872 (resolver.m:1031)
6 libdispatch.dylib 0x000000018f9711c0 _dispatch_client_callout + 16 (object.m:455)
7 libdispatch.dylib 0x000000018f97e860 _dispatch_barrier_sync_f_invoke + 84 (queue.c:3457)
8 libsystem_network.dylib 0x000000018fb2ce78 nw_resolver_set_update_handler + 208 (resolver.m:1275)
9 SystemConfiguration 0x0000000190f8a16c __SCNetworkReachabilityRestartResolver + 260 (SCNetworkReachability.c:1711)
10 SystemConfiguration 0x0000000190f891c8 __SCNetworkReachabilitySetDispatchQueue + 764 (SCNetworkReachability.c:1823)
11 SystemConfiguration 0x0000000190f88ccc SCNetworkReachabilityScheduleWithRunLoop + 504 (SCNetworkReachability.c:1586)
12 CustomKeyboard 0x000000010013f630 -[FIRReachabilityChecker start] + 196
13 CustomKeyboard 0x000000010013abac -[FIRNetwork init] + 156
14 CustomKeyboard 0x0000000100132e28 -[FIRClearcutLogger init] + 416
15 CustomKeyboard 0x0000000100132c68 __35+[FIRClearcutLogger sharedInstance]_block_invoke + 36
16 libdispatch.dylib 0x000000018f9711c0 _dispatch_client_callout + 16 (object.m:455)
17 libdispatch.dylib 0x000000018f971fb4 dispatch_once_f + 56 (once.c:57)
18 CustomKeyboard 0x0000000100132c40 +[FIRClearcutLogger sharedInstance] + 108
19 CustomKeyboard 0x0000000100137214 +[FIRApp initClearcut] + 60
20 CustomKeyboard 0x0000000100136688 +[FIRApp configureDefaultAppWithOptions:sendingNotifications:] + 132
21 CustomKeyboard 0x000000010013643c +[FIRApp configure] + 316
22 libdispatch.dylib 0x000000018f9711c0 _dispatch_client_callout + 16 (object.m:455)
23 libdispatch.dylib 0x000000018f971fb4 dispatch_once_f + 56 (once.c:57)
24 CustomKeyboard 0x00000001000e314c _TFC19CustomKeyboard22KeyboardViewControllercfT7nibNameGSqSS_6bundleGSqCSo8NSBundle__S0_ + 1500 (KeyboardViewController.swift:90)
25 CustomKeyboard 0x00000001000e3270 _TToFC19CustomKeyboard22KeyboardViewControllercfT7nibNameGSqSS_6bundleGSqCSo8NSBundle__S0_ + 112 (KeyboardViewController.swift:0)
26 UIKit 0x00000001971f7688 -[_UIViewServiceViewControllerOperator __createViewController:withContextToken:fbsDisplays:appearanceSerializedRepresentations:legacyAppearance:traitCollection:initialInterfaceOrientation:hostAccessibilityServerPort:canShowTextServices:replyHandler:] + 2216 (UIViewServiceViewControllerOperator.m:1732)
27 CoreFoundation 0x0000000190aee160 __invoking___ + 144
28 CoreFoundation 0x00000001909e1c3c -[NSInvocation invoke] + 284 (NSForwarding.m:2948)
29 CoreFoundation 0x00000001909e66ec -[NSInvocation invokeWithTarget:] + 60 (NSForwarding.m:3019)
显然，在调用FIRApp.configure()之后，呼叫跟踪正在通过系统库进行。
从堆栈跟踪中观察到的一点是，崩溃与检查设备可达性有关。但是，我尝试重现了没有互联网连接的情况，但它却正常工作。
请注意，所有崩溃都发生在iOS 10上，大部分发生在iPhone 6上。
如果能帮助找出崩溃原因，将不胜感激。