IOS开发笔记（5）程序异常crash捕获与拦截

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]);  
}