IOS使用 swizzle 解决一些错误

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不知道你有没有经常遇到这种参数为 nil 的错误或者是数组错误。

而且现在在多线程中还是大量使用 block 的情况下要查找起来实在是太费劲了
所以我用了个取巧的办法（可能会导致你的逻辑错误）用swizzle 来替换这些没验证的方法
我是按我自己 umeng 的错误统计来写的给出个例子而已

+(void)callSafeCategory{    NSError* error = nil;    [objc_getClass("__NSPlaceholderArray") jr_swizzleMethod:@selector(initWithObjects:count:) withMethod:@selector(SY_safeInitWithObjects:count:) error:&error];    LOG_Error        [objc_getClass("__NSArrayI") jr_swizzleMethod:@selector(objectAtIndex:) withMethod:@selector(SY_safeObjectAtIndex:) error:&error];    LOG_Error        [objc_getClass("__NSArrayM") jr_swizzleMethod:@selector(objectAtIndex:) withMethod:@selector(SY_safeObjectAtIndex:) error:&error];    LOG_Error    [objc_getClass("__NSArrayM") jr_swizzleMethod:@selector(addObject:) withMethod:@selector(SY_safeAddObject:) error:&error];    LOG_Error        [objc_getClass("__NSDictionaryI") jr_swizzleMethod:@selector(objectForKey:) withMethod:@selector(SY_safeObjectForKey:) error:&error];    LOG_Error        [objc_getClass("__NSDictionaryM") jr_swizzleMethod:@selector(objectForKey:) withMethod:@selector(SY_safeObjectForKey:) error:&error];    LOG_Error    [objc_getClass("__NSDictionaryM") jr_swizzleMethod:@selector(setObject:forKey:) withMethod:@selector(SY_safeSetObject:forKey:) error:&error];    LOG_Error            [NSURL jr_swizzleClassMethod:@selector(fileURLWithPath:isDirectory:) withClassMethod:@selector(SY_safeFileURLWithPath:isDirectory:) error:&error];    LOG_Error        [NSFileManager jr_swizzleMethod:@selector(enumeratorAtURL:includingPropertiesForKeys:options:errorHandler:) withMethod:@selector(SY_safeEnumeratorAtURL:includingPropertiesForKeys:options:errorHandler:) error:&error];    LOG_Error}

然后在替换的方法里面加入参数验证

<pre name="code" class="objc">@implementation NSArray(SYSafeCategory)-(id)SY_safeObjectAtIndex:(int)index{    if(index>=0 && index < self.count)    {        return [self SY_safeObjectAtIndex:index];    }    else{#ifdef DEBUG        NSAssert(NO,nil);#endif    }    return nil;}-(id)SY_safeInitWithObjects:(const id [])objects count:(NSUInteger)cnt{    for (int i=0; i<cnt; i++) {        if(objects[i] == nil)            return nil;    }        return [self SY_safeInitWithObjects:objects count:cnt];}@end@implementation NSMutableArray(SYSafeCategory)-(void)SY_safeAddObject:(id)anObject{    if(anObject != nil){        [self SY_safeAddObject:anObject];    }}@end

示例地址：
http://download.csdn.net/detail/li6185377/6400383

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