iOS中App崩溃问题是在所难免的，那如何在崩溃之前给用户一些提示，或是可以将这些崩溃信息发送给自己，以便于自己修正呢？前段时间做项目时，一直没添加这方面的功能，这两天没事从网上看了些资料，顺便自己做了个Demo测试了一下，今天把我了解的东西整理一下。
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。
Demo运行环境:Xcode7.3, iOS9.3
步骤一：定义一个UncaughtExceptionHandler类
UncaughtExceptionHandler.h内容：
#import <UIKit/UIKit.h>
@interface UncaughtExceptionHandler : NSObject
{
BOOL dismissed;
}
@end
void InstallUncaughtExceptionHandler();
UncaughtExceptionHandler.m内容：
#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
+ (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;
}
}
- (void)handleException:(NSException *)exception
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"程序出现问题啦", nil) message:[NSString stringWithFormat:NSLocalizedString(@"崩溃信息\n"@"%@\n%@", nil), [exception reason], [[exception userInfo] objectForKey:UncaughtExceptionHandlerAddressesKey]] delegate:self cancelButtonTitle:NSLocalizedString(@"离开", nil) otherButtonTitles:nil];
[alert show];
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);
if ([[exception name] isEqual:UncaughtExceptionHandlerSignalExceptionName])
{
kill(getpid(), [[[exception userInfo] objectForKey:UncaughtExceptionHandlerSignalKey] intValue]);
}
else
{
[exception raise];
}
}
@end
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];
NSLog(@"Crash!!!! %@", appInfo);
return appInfo;
}
void MySignalHandler(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];
// 创建一个OC异常对象
NSException *ex = [NSException exceptionWithName:UncaughtExceptionHandlerSignalExceptionName reason:[NSString stringWithFormat:NSLocalizedString(@"Signal %d was raised.\n"@"%@", nil), signal, getAppInfo()] userInfo:userInfo];
// 处理异常消息
[[[UncaughtExceptionHandler alloc] init] performSelectorOnMainThread:@selector(handleException:) withObject:ex waitUntilDone:YES];
}
void InstallUncaughtExceptionHandler()
{
signal(SIGABRT, MySignalHandler);
signal(SIGILL, MySignalHandler);
signal(SIGSEGV, MySignalHandler);
signal(SIGFPE, MySignalHandler);
signal(SIGBUS, MySignalHandler);
signal(SIGPIPE, MySignalHandler);
}
步骤二：在AppDelegate中导入本类
#import "UncaughtExceptionHandler.h"
- (void)installUncaughtExceptionHandler
{
InstallUncaughtExceptionHandler();
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
[self installUncaughtExceptionHandler];
return YES;
}
效果图如下：
崩溃截图.png
当然，也可以把这些崩溃信息通过邮箱发送给自己，这个根据项目需求来自定义。
