上一篇見iOS常見Crash案例總結

iOS Crash捕獲

iOS端的crash分為兩類，一類是NSException異常，另外一類是Signal信號異常。這兩類異常我們都可以通過注冊相關函數來捕獲。

Crash種類

1、對于unrecognized selector sent to instance找不到方法iOS系統拋出異常崩潰，給NSObject添加一個分類，實現消息轉發的幾個方法

當無實現的方法時消息轉發流程.jpeg

利用runtime消息轉發處理未實現的方法crash，代碼如下：

#import <objc/runtime.h>

static NSString *_errorFunctionName;
void dynamicMethodIMP(id self,SEL _cmd) {}

static inline void change_method(Class _originalClass ,SEL _originalSel,Class _newClass ,SEL _newSel) {
    Method methodOriginal = class_getInstanceMethod(_originalClass, _originalSel);
    Method methodNew = class_getInstanceMethod(_newClass, _newSel);
    method_exchangeImplementations(methodOriginal, methodNew);
}

@implementation NSObject(UnRecognized)
+ (void)load {
    change_method([self class], @selector(methodSignatureForSelector:), [self class], @selector(ws_methodSignatureForSelector:));
    change_method([self class], @selector(forwardInvocation:), [self class], @selector(ws_forwardInvocation:));
}

- (NSMethodSignature *)ws_methodSignatureForSelector:(SEL)aSelector {
    if (![self respondsToSelector:aSelector]) {
        _errorFunctionName = NSStringFromSelector(aSelector);
        NSMethodSignature *methodSignature = [self ws_methodSignatureForSelector:aSelector];
        if (class_addMethod([self class], aSelector, (IMP)dynamicMethodIMP, method_getTypeEncoding(class_getInstanceMethod([self class], @selector(methodSignatureForSelector:))))) {
            NSLog(@"添加臨時方法成功！");
        }
        if (!methodSignature) {
            methodSignature = [self ws_methodSignatureForSelector:aSelector];
        }
        return methodSignature;
    }else{
        return [self ws_methodSignatureForSelector:aSelector];
    }
}

- (void)ws_forwardInvocation:(NSInvocation *)anInvocation{
    SEL selector = [anInvocation selector];
    if ([self respondsToSelector:selector]) {
        [anInvocation invokeWithTarget:self];
    }else{
        [self ws_forwardInvocation:anInvocation];
    }
}

@end

2、對于signal產生的crash，創建一個crash捕獲的單例，里面進行信號捕捉處理，只需要在AppDelegate中進行初始化

#import "WSCrashHandler.h"
#include <libkern/OSAtomic.h>
#include <execinfo.h>
#include <sys/signal.h>
NSString * const kSignalExceptionName = @"kSignalExceptionName";
NSString * const kSignalKey = @"kSignalKey";
NSString * const kCaughtExceptionStackInfoKey = @"kCaughtExceptionStackInfoKey";

static void HandleException(NSException *exception);
static void SignalHandler(int signal);

@interface WSCrashHandler ()
@property (nonatomic, assign) BOOL dismissed;
@end

@implementation WSCrashHandler

+ (instancetype)shared {
    static WSCrashHandler *sharedHelper = nil;
    static dispatch_once_t predicate;
    dispatch_once(&predicate, ^{
        sharedHelper = [[WSCrashHandler alloc] init];
    });
    return sharedHelper;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        // 1.捕獲一些異常導致的崩潰
        NSSetUncaughtExceptionHandler(&HandleException);
        
        // 2.捕獲非異常情況，通過signal傳遞出來的崩潰
        //signal是一個函數，有2個參數，第一個是int類型，第二個參數是一個函數指針
        //添加想要監聽的signal類型，當發出相應類型的signal時，會回調SignalHandler方法
        signal(SIGABRT, SignalHandler);// SIGABRT--程序中止命令中止信號
        signal(SIGILL, SignalHandler);//SIGILL--程序非法指令信號
        signal(SIGSEGV, SignalHandler);//SIGSEGV--程序無效內存中止信號
        signal(SIGFPE, SignalHandler);//SIGFPE--程序浮點異常信號
        signal(SIGBUS, SignalHandler);//SIGBUS--程序內存字節未對齊中止信號
        signal(SIGPIPE, SignalHandler);//SIGPIPE--程序Socket發送失敗中止信號
    }
    return self;
}

//NSException異常是OC代碼導致的crash
void HandleException(NSException *exception) {
    NSString *message = [NSString stringWithFormat:@"崩潰原因如下:\n%@\n%@",
                         [exception reason],
                         [[exception userInfo] objectForKey:kCaughtExceptionStackInfoKey]];
    NSLog(@"%@",message);
    
    // 獲取NSException異常的堆棧信息
    NSArray *callStack = [exception callStackSymbols];
    NSMutableDictionary *userInfo = [NSMutableDictionary dictionaryWithDictionary:[exception userInfo]];
    [userInfo setObject:callStack forKey:kCaughtExceptionStackInfoKey];
    
    WSCrashHandler *crashObject = [WSCrashHandler shared];
    NSException *customException = [NSException exceptionWithName:[exception name] reason:[exception reason] userInfo:userInfo];
    [crashObject performSelectorOnMainThread:@selector(handleException:) withObject:customException waitUntilDone:YES];
}
//signal信號拋出的異常處理
void SignalHandler(int signal) {
    NSArray *callStack = [WSCrashHandler backtrace];
    NSLog(@"signal信號捕獲崩潰，堆棧信息：%@",callStack);
    
    WSCrashHandler *crashObject = [WSCrashHandler shared];
    NSException *customException = [NSException exceptionWithName:kSignalExceptionName
                                                           reason:[NSString stringWithFormat:NSLocalizedString(@"Signal %d was raised.", nil),signal]
                                                         userInfo:@{kSignalKey:[NSNumber numberWithInt:signal]}];
    
    [crashObject performSelectorOnMainThread:@selector(handleException:) withObject:customException waitUntilDone:YES];
}

- (void)handleException:(NSException *)exception {
    // 打印或彈出框
    // TODO :
#ifdef DEBUG
    NSString *message = [NSString stringWithFormat:@"抱歉，APP發生了異常，點擊屏幕繼續并自動復制錯誤信息到剪切板。\n\n異常報告:\n異常名稱：%@\n異常原因：%@\n", [exception name], [exception reason]];
    NSLog(@"%@",message);
    [self showCrashToastWithMessage:message];
    
    CFRunLoopRef runLoop = CFRunLoopGetCurrent();
    CFArrayRef allModes = CFRunLoopCopyAllModes(runLoop);
    while (!self.dismissed) {
        for (NSString *mode in (__bridge NSArray *)allModes) {
            //為阻止線程退出，使用 CFRunLoopRunInMode(model, 0.001, false)等待系統消息，false表示RunLoop沒有超時時間
            CFRunLoopRunInMode((CFStringRef)mode, 0.001, false);
        }
    }
    CFRelease(allModes);
#endif
    // 本地保存exception異常信息并上傳服務器
    // TODO :
    
    // 下面等同于清空之前設置的
    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);
    
    // 殺死 或 喚起
    if ([[exception name] isEqual:kSignalExceptionName]) {
        kill(getpid(), [[[exception userInfo] objectForKey:kSignalKey] intValue]);
    } else {
        [exception raise];
    }
}

//該函數用來獲取當前線程調用堆棧的信息，并且轉化為字符串數組。
+ (NSArray *)backtrace {
    void *callStack[128];//堆棧方法數組
    int frames = backtrace(callStack, 128);//獲取錯誤堆棧方法指針數組，返回數目
    char **strs = backtrace_symbols(callStack, frames);//符號化
    
    NSMutableArray *backtrace = [NSMutableArray arrayWithCapacity:frames]; //函數調用信息依照順序存在NSMutableArray backtrace
    for (int i = 0; i < frames; i++) {
        [backtrace addObject:[NSString stringWithUTF8String:strs[i]]];
    }
    free(strs);
    return backtrace;
}

- (void)showCrashToastWithMessage:(NSString *)message {
    UILabel *crashLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 64, [UIApplication sharedApplication].keyWindow.bounds.size.width, [UIApplication sharedApplication].keyWindow.bounds.size.height - 64)];
    crashLabel.textColor = [UIColor redColor];
    crashLabel.font = [UIFont systemFontOfSize:15];
    crashLabel.text = message;
    crashLabel.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.7];
    crashLabel.numberOfLines = 0;
    [[UIApplication sharedApplication].keyWindow addSubview:crashLabel];
    
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(crashToastTapAction:)];
    crashLabel.userInteractionEnabled = YES;
    [crashLabel addGestureRecognizer:tap];
}
- (void)crashToastTapAction:(UITapGestureRecognizer *)tap {
    UILabel *crashLabel = (UILabel *)tap.view;
    [UIPasteboard generalPasteboard].string = crashLabel.text;
    self.dismissed = YES;
}

@end

3、實例測試：

關鍵點：SignalHandler不要在debug環境下測試。因為系統的debug會優先去攔截。先在run的切換Release狀態,運行安裝后，再手動點擊啟動app去測試。

搞成relese模式.png

實例測試代碼如下：

#import "ViewController.h"

@interface ViewController ()

@end

typedef struct Test {
    int a;
    int b;
}Test;

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    // Do any additional setup after loading the view.
    
    UIButton *crashExcButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 44, self.view.bounds.size.width, 50)];
    crashExcButton.backgroundColor = [UIColor redColor];
    [crashExcButton setTitle:@"Exception" forState:UIControlStateNormal];
    [crashExcButton addTarget:self action:@selector(crashExcClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:crashExcButton];
    
    UIButton *crashSignalEGVButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 60+44, self.view.bounds.size.width, 50)];
    crashSignalEGVButton.backgroundColor = [UIColor redColor];
    [crashSignalEGVButton setTitle:@"Signal(EGV)" forState:UIControlStateNormal];
    [crashSignalEGVButton addTarget:self action:@selector(crashSignalEGVClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:crashSignalEGVButton];
    
    UIButton *crashSignalBRTButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 120+44, self.view.bounds.size.width, 50)];
    crashSignalBRTButton.backgroundColor = [UIColor redColor];
    [crashSignalBRTButton setTitle:@"Signal(ABRT)" forState:UIControlStateNormal];
    [crashSignalBRTButton addTarget:self action:@selector(crashSignalBRTClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:crashSignalBRTButton];
    
    UIButton *crashSignalBUSButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 180+44, self.view.bounds.size.width, 50)];
    crashSignalBUSButton.backgroundColor = [UIColor redColor];
    [crashSignalBUSButton setTitle:@"Signal(BUS)" forState:UIControlStateNormal];
    [crashSignalBUSButton addTarget:self action:@selector(crashSignalBUSClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:crashSignalBUSButton];
}

- (void)crashSignalEGVClick {
    UIView *view = [[UIView alloc] init];
    [view performSelector:NSSelectorFromString(@"release")];//導致SIGSEGV的錯誤，一般會導致進程流產
    view.backgroundColor = [UIColor whiteColor];
}

- (void)crashSignalBRTClick {
    Test *pTest = {1,2};
    free(pTest);//導致SIGABRT的錯誤，因為內存中根本就沒有這個空間，哪來的free，就在棧中的對象而已
    pTest->a = 5;
}

- (void)crashSignalBUSClick {
    //SIGBUS，內存地址未對齊
    //EXC_BAD_ACCESS(code=1,address=0x1000dba58)
    char *s = "hello world";
    *s = 'H';
}

- (void)crashExcClick {
    [self performSelector:@selector(aaaa)];
}

@end