UncaughtExceptionHandler

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，代码如下：

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>  

@interface UncaughtExceptionHandler : NSObject
{
    BOOL dismissed;
}
+(void) InstallUncaughtExceptionHandler;
@end  

//利用 NSSetUncaughtExceptionHandler，当程序异常退出的时候，可以先进行处理，然后做一些自定义的动作，比如下面一段代码，就是网上有人写的，直接在发生异常时给某人发送邮件，</span>
void UncaughtExceptionHandlers (NSException *exception);  

#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 = ;
const int32_t UncaughtExceptionMaximum = ;
const NSInteger UncaughtExceptionHandlerSkipAddressCount = ;
const NSInteger UncaughtExceptionHandlerReportAddressCount = ;
NSString* getAppInfo()
{
    NSString *appInfo = [NSString stringWithFormat:@"App : %@ %@(%@)\nDevice : %@\nOS Version : %@ %@\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;
    }
    if(signal==)
    {//比较坑爹的是 我遇到的一个问题只有iPhone5出现问题 但是我这边测试的没有iPhone5 无法直接log  可能是内存不足 果然 删除几个应用就可以了 所以加了这句
        UIAlertView * tip2 = [[UIAlertView alloc]initWithTitle:@"可能原因:key" message:@"内存不足" delegate:nil cancelButtonTitle:@"ok" otherButtonTitles:nil];
        [tip2 show];
        [tip2 release];
    }  

    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];  

}  

@implementation UncaughtExceptionHandler
+(void) InstallUncaughtExceptionHandler
{
    signal(SIGABRT, MySignalHandler);
    signal(SIGILL, MySignalHandler);
    signal(SIGSEGV, MySignalHandler);
    signal(SIGFPE, MySignalHandler);
    signal(SIGBUS, MySignalHandler);
    signal(SIGPIPE, MySignalHandler);
}
+ (NSArray *)backtrace
{
    void* callstack[];
    int frames = backtrace(callstack, );
    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 == )
    {
        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];
    }
}
void UncaughtExceptionHandlers (NSException *exception) {
    NSArray *arr = [exception callStackSymbols];
    NSString *reason = [exception reason];
    NSString *name = [exception name];
    NSString *urlStr = [NSString stringWithFormat:@"mailto://[e-mail]?subject=bug报告&body=感谢您的配合!<br><br><br>"
                        "错误详情:<br>%@<br>--------------------------<br>%@<br>---------------------<br>%@",
                        name,reason,[arr componentsJoinedByString:@"<br>"]];
    NSURL *url = [NSURL URLWithString:[urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
    [[UIApplication sharedApplication] openURL:url];  

    //或者直接用代码，输入这个崩溃信息，以便在console中进一步分析错误原因
    NSLog(@"1heqin, CRASH: %@", exception);
    NSLog(@"heqin, Stack Trace: %@", [exception callStackSymbols]);
}  

@end  

//然后在delegate文件里面- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions函数里面
[UncaughtExceptionHandler InstallUncaughtExceptionHandler];
   NSSetUncaughtExceptionHandler (&UncaughtExceptionHandlers);