IOS开发笔记（5）程序异常crash捕获与拦截

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开发iOS应用，解决Crash问题始终是一个难题。Crash分为两种，一种是由EXC_BAD_ACCESS引起的，原因是访问了不属于本进程的内存地址，有可能是访问已被释放的内存；另一种是未被捕获的Objective-C异常（NSException），导致程序向自身发送了SIGABRT信号而崩溃。其实对于未捕获的Objective-C异常，我们是有办法将它记录下来的，如果日志记录得当，能够解决绝大部分崩溃的问题。这里对于UI线程与后台线程分别说明。

一：在.h文件中编写

 @interface UncaughtExceptionHandler : NSObject{
     BOOL dismissed;
 }

 @end
 void HandleException(NSException *exception);
 void SignalHandler(int signal);


 void InstallUncaughtExceptionHandler(void);

二：在.m文件编写

 #import "UncaughtExceptionHandler.h"
 #include <libkern/OSAtomic.h>
 #include <execinfo.h>

 //http://www.cocoachina.com/newbie/tutorial/2012/0829/4672.html
 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;
     }else if (anIndex==1) {
         NSLog(@"ssssssss");
     }
 }

 - (void)validateAndSaveCriticalApplicationData
 {

 }

 - (void)handleException:(NSException *)exception
 {
     [self validateAndSaveCriticalApplicationData];

     UIAlertView *alert =
         [[[UIAlertView alloc]
             initWithTitle:NSLocalizedString(@"抱歉，程序出现了异常", nil)
             message:[NSString stringWithFormat:NSLocalizedString(
                 @"如果点击继续，程序有可能会出现其他的问题，建议您还是点击退出按钮并重新打开\n\n"
                 @"异常原因如下:\n%@\n%@", nil),
                 [exception reason],
                 [[exception userInfo] objectForKey:UncaughtExceptionHandlerAddressesKey]]
             delegate:self
             cancelButtonTitle:NSLocalizedString(@"退出", nil)
             otherButtonTitles:NSLocalizedString(@"继续", 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

 void HandleException(NSException *exception)
 {
     int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount);
     if (exceptionCount > UncaughtExceptionMaximum)
     {
         return;
     }

     NSArray *callStack = [UncaughtExceptionHandler backtrace];
     NSMutableDictionary *userInfo =
         [NSMutableDictionary dictionaryWithDictionary:[exception userInfo]];
     [userInfo
         setObject:callStack
         forKey:UncaughtExceptionHandlerAddressesKey];

     [[[[UncaughtExceptionHandler alloc] init] autorelease]
         performSelectorOnMainThread:@selector(handleException:)
         withObject:
             [NSException
                 exceptionWithName:[exception name]
                 reason:[exception reason]
                 userInfo:userInfo]
         waitUntilDone:YES];
 }

 void SignalHandler(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.", nil),
                         signal]
                 userInfo:
                     [NSDictionary
                         dictionaryWithObject:[NSNumber numberWithInt:signal]
                         forKey:UncaughtExceptionHandlerSignalKey]]
         waitUntilDone:YES];
 }

 void InstallUncaughtExceptionHandler(void)
 {
     NSSetUncaughtExceptionHandler(&HandleException);
     signal(SIGABRT, SignalHandler);
     signal(SIGILL, SignalHandler);
     signal(SIGSEGV, SignalHandler);
     signal(SIGFPE, SignalHandler);
     signal(SIGBUS, SignalHandler);
     signal(SIGPIPE, SignalHandler);
 }

三：最后在AppDelegate中创建

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
   InstallUncaughtExceptionHandler();
     self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
     // Override point for customization after application launch.
   self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];
   self.window.rootViewController = self.viewController;
     [self.window makeKeyAndVisible];
     return YES;
 }

四：最后的测试

 - (IBAction)onclcko:(id)sender {
    //  [alert show];
     NSArray *arry=[NSArray arrayWithObject:@"sss"];
     NSLog(@"%@",[arry objectAtIndex:1]);
 }

五：结果