iOS中程序异常Crash友好化处理详解

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
 // Override point for customization after application launch.
 
 [UncaughtExceptionHandler installUncaughtExceptionHandler:YES showAlert:YES];
 return YES;
}

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

@interface UncaughtExceptionHandler : NSObject

/*!
 * 异常的处理方法
 *
 * @param install 是否开启捕获异常
 * @param showAlert 是否在发生异常时弹出alertView
 */
+ (void)installUncaughtExceptionHandler:(BOOL)install showAlert:(BOOL)showAlert;
@end

/*
 * 异常的处理方法
 *
 * @param install  是否开启捕获异常
 * @param showAlert 是否在发生异常时弹出alertView
 */
+ (void)installUncaughtExceptionHandler:(BOOL)install showAlert:(BOOL)showAlert {
  
  if (install && showAlert) {
    [[self alloc] alertView:showAlert];
  }
  
  NSSetUncaughtExceptionHandler(install ? HandleException : NULL);
  signal(SIGABRT, install ? SignalHandler : SIG_DFL);
  signal(SIGILL, install ? SignalHandler : SIG_DFL);
  signal(SIGSEGV, install ? SignalHandler : SIG_DFL);
  signal(SIGFPE, install ? SignalHandler : SIG_DFL);
  signal(SIGBUS, install ? SignalHandler : SIG_DFL);
  signal(SIGPIPE, install ? SignalHandler : SIG_DFL);
}

void HandleException(NSException *exception) {
  
  
  int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount);
  // 如果太多不用处理
  if (exceptionCount > UncaughtExceptionMaximum) {
    return;
  }
  
  //获取调用堆栈
  NSArray *callStack = [exception callStackSymbols];
  NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithDictionary:[exception userInfo]];
  [userInfo setObject:callStack forKey:UncaughtExceptionHandlerAddressesKey];
  
  //在主线程中，执行制定的方法, withObject是执行方法传入的参数
  [[[UncaughtExceptionHandler alloc] init]
   performSelectorOnMainThread:@selector(handleException:)
   withObject:
   [NSException exceptionWithName:[exception name]
               reason:[exception reason]
              userInfo:userInfo]
   waitUntilDone:YES];
}

//处理signal报错
void SignalHandler(int signal) {
  
  int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount);
  // 如果太多不用处理
  if (exceptionCount > UncaughtExceptionMaximum) {
    return;
  }
  
  NSString* description = nil;
  switch (signal) {
    case SIGABRT:
      description = [NSString stringWithFormat:@"Signal SIGABRT was raised!\n"];
      break;
    case SIGILL:
      description = [NSString stringWithFormat:@"Signal SIGILL was raised!\n"];
      break;
    case SIGSEGV:
      description = [NSString stringWithFormat:@"Signal SIGSEGV was raised!\n"];
      break;
    case SIGFPE:
      description = [NSString stringWithFormat:@"Signal SIGFPE was raised!\n"];
      break;
    case SIGBUS:
      description = [NSString stringWithFormat:@"Signal SIGBUS was raised!\n"];
      break;
    case SIGPIPE:
      description = [NSString stringWithFormat:@"Signal SIGPIPE was raised!\n"];
      break;
    default:
      description = [NSString stringWithFormat:@"Signal %d was raised!",signal];
  }
  
  NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
  NSArray *callStack = [UncaughtExceptionHandler backtrace];
  [userInfo setObject:callStack forKey:UncaughtExceptionHandlerAddressesKey];
  [userInfo setObject:[NSNumber numberWithInt:signal] forKey:UncaughtExceptionHandlerSignalKey];
  
  //在主线程中，执行指定的方法, withObject是执行方法传入的参数
  [[[UncaughtExceptionHandler alloc] init]
   performSelectorOnMainThread:@selector(handleException:)
   withObject:
   [NSException exceptionWithName:UncaughtExceptionHandlerSignalExceptionName
               reason: description
              userInfo: userInfo]
   waitUntilDone:YES];
}

//获取调用堆栈
+ (NSArray *)backtrace {
  
  //指针列表
  void* callstack[128];
  //backtrace用来获取当前线程的调用堆栈，获取的信息存放在这里的callstack中
  //128用来指定当前的buffer中可以保存多少个void*元素
  //返回值是实际获取的指针个数
  int frames = backtrace(callstack, 128);
  //backtrace_symbols将从backtrace函数获取的信息转化为一个字符串数组
  //返回一个指向字符串数组的指针
  //每个字符串包含了一个相对于callstack中对应元素的可打印信息，包括函数名、偏移地址、实际返回地址
  char **strs = backtrace_symbols(callstack, frames);
  
  int i;
  NSMutableArray *backtrace = [NSMutableArray arrayWithCapacity:frames];
  for (i = 0; i < frames; i++) {
    
    [backtrace addObject:[NSString stringWithUTF8String:strs[i]]];
  }
  free(strs);
  
  return backtrace;
}

- (void)handleException:(NSException *)exception {
  
  [self validateAndSaveCriticalApplicationData:exception];
  
  if (!showAlertView) {
    return;
  }
  
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
  UIAlertView *alert =
  [[UIAlertView alloc]
   initWithTitle:@"出错啦"
   message:[NSString stringWithFormat:@"你可以尝试继续操作，但是应用可能无法正常运行.\n"]
   delegate:self
   cancelButtonTitle:@"退出"
   otherButtonTitles:@"继续", nil];
  [alert show];
#pragma clang diagnostic pop
  
  CFRunLoopRef runLoop = CFRunLoopGetCurrent();
  CFArrayRef allModes = CFRunLoopCopyAllModes(runLoop);
  
  while (!self.dismissed) {
    //点击继续
    for (NSString *mode in (__bridge NSArray *)allModes) {
      //快速切换Mode
      CFRunLoopRunInMode((CFStringRef)mode, 0.001, false);
    }
  }
  
  //点击退出
  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];
  }
}