做程序员的都知道,BUG永远是改不完的,如果已经上线的版本出现闪退的情况, 会让用户体验非常不好.所以天朝的骑士们搞出了这个叫crash的东西,大致的道理呢,就是利用RunLoop,来判断要不要进行下一步操作,在你的代码出错的时候, 例如数组越界,那么就会触发这个机制,RunLoop就会告诉你,可以自定义弹出框来告诉用户下一步会出问题不要进行下一步了,或者你自己强制不进行下一步,加一个小提醒不让用户迷茫就行.闲话少说, 看代码.

首先在AppDelegate.m的- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions ;方法里,添加这句代码:
InstallUncaughtExceptionHandler();// 拦截崩溃.
当然,这个也可以在你建立好崩溃拦截的类后来添加.都是一样的.

生成一个继承于NSObject的类, .h文件里写上下面这些就够了
.h 文件代码:

import <Foundation/Foundation.h>

import <UIKit/UIKit.h>

@interface UncaughtExceptionHandler : NSObject
{
BOOL dismissed;
}
@end
void HandleException(NSException *exception);
void SignalHandler(int signal);
void InstallUncaughtExceptionHandler(void);

然后就是核心代码了,.会为你一一呈现
.m 文件代码:

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

// 程序崩溃2(程序崩溃第二步走的方法)

(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 {
// 崩溃拦截可以做的事,写在这个方法也是极好的
}
// 程序崩溃3(程序崩溃是第三进入的方法)
(void)handleException:(NSException *)exception {
[self validateAndSaveCriticalApplicationData];

//这里可以打印或者显示出ERROR的原因.
// NSString *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"@"异常原因如下:\n%@\n%@",nil),[exception reason],[[exception userInfo] objectForKey:UncaughtExceptionHandlerAddressesKey]];

//设置弹出框来了提醒用户, 当然也可以是自己设计其他内容,
NSString *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",nil)];
UIAlertView *alert =[[UIAlertView alloc]initWithTitle:NSLocalizedString(@"抱歉，程序出现了异常",nil)
message:message
delegate:self
cancelButtonTitle:NSLocalizedString(@"继续",nil)
otherButtonTitles:NSLocalizedString(@"退出",nil), nil];
[alert show];

// 利用RunLoop , 来完成拦截的操作
CFRunLoopRef runLoop = CFRunLoopGetCurrent();
CFArrayRef allModes = CFRunLoopCopyAllModes(runLoop);

while (!dismissed) {
    for (NSString *mode in (__bridge 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);

[exception raise];
if ([[exception name] isEqual:UncaughtExceptionHandlerSignalExceptionName]) {
    kill(getpid(), [[[exception userInfo] objectForKey:UncaughtExceptionHandlerSignalKey]intValue]);
}else{
    [exception raise];
}

}

@end
// 程序崩溃时1(程序崩溃是首先进入的方法, 你可以debug自己调试)
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]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] 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];

}

//. 进入程序时(在AppDelegate.m)里添加那行代码后,就会启用这行代码了
void InstallUncaughtExceptionHandler(void) {

NSSetUncaughtExceptionHandler(&HandleException);

signal(SIGHUP, SignalHandler); 
signal(SIGINT, SignalHandler);
signal(SIGQUIT, SignalHandler);


signal(SIGABRT,SignalHandler);
signal(SIGILL,SignalHandler);
signal(SIGSEGV,SignalHandler);
signal(SIGFPE,SignalHandler);
signal(SIGBUS,SignalHandler);
signal(SIGPIPE,SignalHandler);

}
//好啦,这些就完全够了,当你的程序遇到崩溃的时候, 就会稳稳的跳出提示信息, 继续就真的崩溃的, 退出就不会进行下一步操作了.还有一点要注意,当你连到真机上测试的时候,这个崩溃只会提示一次,你再次点击的时候他就不弹出提示而是直接崩溃了,所以你要是测试的话,把程序运行后, 拔掉真机, 不要连接电脑就可以了.

iOS强大的crash, 拦截崩溃, 防止闪退