如何让IOS应用从容地崩溃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。文/donglin 注:鉴于多名网友对文中代码提出的质疑,小编联系了作者,迅速给予更正并更新。感谢大家的监督与支持! 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: #import <UIKit/UIKit.h> @interface UncaughtExceptionHandler : NSObject { BOOL dismissed; } @end void InstallUncaughtExceptionHandler();
然后在.mm文件实现InstallUncaughtExceptionHandler(),如下: 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: #import "UncaughtExceptionHandler.h" #include <libkern/OSAtomic.h> #include <execinfo.h> 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 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: - (void)installUncaughtExceptionHandler { InstallUncaughtExceptionHandler(); }
最后,在 didFinishLaunchingWithOptions 中加入这一句代码就行了: [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。
原文来自:触控科技博客 |
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