IOS崩溃(NSSetUncaughtExceptionHa…

虽然大家都不愿意看到程序崩溃，但可能崩溃是每个应用必须面对的现实，既然崩溃已经发生，无法阻挡了，那我们就让它崩也崩得淡定点吧。

IOS SDK中提供了一个现成的函数 NSSetUncaughtExceptionHandler 用来做异常处理，但功能非常有限，而引起崩溃的大多数原因如：内存访问错误，重复释放等错误就无能为力了，因为这种错误它抛出的是Signal，所以必须要专门做Signal处理。首先定义一个UncaughtExceptionHandler类，.h头文件的代码如下：

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#import @interface UncaughtExceptionHandler : NSObject{ BOOL dismissed; } @end

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1	void InstallUncaughtExceptionHandler();

然后在.mm文件实现InstallUncaughtExceptionHandler()，如下：

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void InstallUncaughtExceptionHandler(){ signal(SIGABRT, MySignalHandler); signal(SIGILL, MySignalHandler); signal(SIGSEGV, MySignalHandler); signal(SIGFPE, MySignalHandler); signal(SIGBUS, MySignalHandler); signal(SIGPIPE, MySignalHandler); }

这样，当应用发生错误而产生上述Signal后，就将会进入我们自定义的回调函数MySignalHandler。为了得到崩溃时的现场信息，还可以加入一些获取CallTrace及设备信息的代码，.mm文件的完整代码如下：

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#import "UncaughtExceptionHandler.h" #include #include NSString * const UncaughtExceptionHandlerSignalExceptionName = @"UncaughtExceptionHandlerSignalExceptionName"; NSString * const UncaughtExceptionHandlerSignalKey = @"UncaughtExceptionHandlerSignalKey"; NSString * const UncaughtExceptionHandlerAddressesKey = @"UncaughtExceptionHandlerAddressesKey"; volatile int32_t UncaughtExceptionCount = 0; const int32_t UncaughtExceptionMaximum = 10; const NSInteger UncaughtExceptionHandlerSkipAddressCount = 4; const NSInteger UncaughtExceptionHandlerReportAddressCount = 5; @implementation UncaughtExceptionHandler + (NSArray *)backtrace { void* callstack[128]; int frames = backtrace(callstack, 128); char **strs = backtrace_symbols(callstack, frames);      int i; NSMutableArray *backtrace = [NSMutableArray arrayWithCapacity:frames]; for ( i = UncaughtExceptionHandlerSkipAddressCount; i < UncaughtExceptionHandlerSkipAddressCount + UncaughtExceptionHandlerReportAddressCount; i++) { [backtrace addObject:[NSString stringWithUTF8String:strs[i]]]; } free(strs);      return backtrace; } - (void)alertView:(UIAlertView *)anAlertView clickedButtonAtIndex:(NSInteger)anIndex { if (anIndex == 0) { dismissed = YES; } } - (void)handleException:(NSException *)exception { UIAlertView *alert = [[[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Unhandled exception", nil) message:[NSString stringWithFormat:NSLocalizedString( @"You can try to continue but the application may be unstable.\n" @"%@\n%@", nil), [exception reason], [[exception userInfo] objectForKey:UncaughtExceptionHandlerAddressesKey]] delegate:self cancelButtonTitle:NSLocalizedString(@"Quit", nil) otherButtonTitles:NSLocalizedString(@"Continue", nil), nil] autorelease]; [alert show];    CFRunLoopRef runLoop = CFRunLoopGetCurrent(); CFArrayRef allModes = CFRunLoopCopyAllModes(runLoop);    while (!dismissed) { for (NSString *mode in (NSArray *)allModes) { CFRunLoopRunInMode((CFStringRef)mode, 0.001, false); } }    CFRelease(allModes); NSSetUncaughtExceptionHandler(NULL); signal(SIGABRT, SIG_DFL); signal(SIGILL, SIG_DFL); signal(SIGSEGV, SIG_DFL); signal(SIGFPE, SIG_DFL); signal(SIGBUS, SIG_DFL); signal(SIGPIPE, SIG_DFL);    if ([[exception name] isEqual:UncaughtExceptionHandlerSignalExceptionName]) { kill(getpid(), [[[exception userInfo] objectForKey:UncaughtExceptionHandlerSignalKey] intValue]); } else { [exception raise]; } } @end

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NSString* getAppInfo() { NSString *appInfo = [NSString stringWithFormat:@"App : %@ %@(%@)\nDevice : %@\nOS Version : %@ %@\nUDID : %@\n", [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleDisplayName"], [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"], [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"], [UIDevice currentDevice].model, [UIDevice currentDevice].systemName, [UIDevice currentDevice].systemVersion, [UIDevice currentDevice].uniqueIdentifier]; NSLog(@"Crash!!!! %@", appInfo); return appInfo; } void MySignalHandler(int signal) { int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount); if (exceptionCount > UncaughtExceptionMaximum) { return; } NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithObject:[NSNumber numberWithInt:signal] forKey:UncaughtExceptionHandlerSignalKey]; NSArray *callStack = [UncaughtExceptionHandler backtrace]; [userInfo setObject:callStack forKey:UncaughtExceptionHandlerAddressesKey]; [[[[UncaughtExceptionHandler alloc] init] autorelease] performSelectorOnMainThread:@selector(handleException:) withObject: [NSException exceptionWithName:UncaughtExceptionHandlerSignalExceptionName reason: [NSString stringWithFormat: NSLocalizedString(@"Signal %d was raised.\n" @"%@", nil), signal, getAppInfo()] userInfo: [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:signal] forKey:UncaughtExceptionHandlerSignalKey]] waitUntilDone:YES]; } void InstallUncaughtExceptionHandler() { signal(SIGABRT, MySignalHandler); signal(SIGILL, MySignalHandler); signal(SIGSEGV, MySignalHandler); signal(SIGFPE, MySignalHandler); signal(SIGBUS, MySignalHandler); signal(SIGPIPE, MySignalHandler); }

在应用自身的 didFinishLaunchingWithOptions 前，加入一个函数：

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- (void)installUncaughtExceptionHandler { InstallUncaughtExceptionHandler(); }

最后，在 didFinishLaunchingWithOptions 中加入这一句代码就行了：

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1	[self InstallUncaughtExceptionHandler];

现在，基本上所有崩溃都能Hold住了。崩溃时将会显示出如下的对话框：

这样在崩溃时还能从容地弹出对话框，比起闪退来，用户也不会觉得那么不爽。然后在下次启动时还可以通过邮件来发送Crash文件到邮箱，这就看各个应用的需求了。

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