iOS开发中两个不错的宏定义

/** Synthsize a weak or strong reference. Example: @weakify(self) [self doSomething^{ @strongify(self) if (!self) return; ... }]; */ #ifndef weakify #if DEBUG #if __has_feature(objc_arc) #define weakify(object) autoreleasepool{} __weak __typeof__(object) weak##_##object = object; #else #define weakify(object) autoreleasepool{} __block __typeof__(object) block##_##object = object; #endif #else #if __has_feature(objc_arc) #define weakify(object) try{} @finally{} {} __weak __typeof__(object) weak##_##object = object; #else #define weakify(object) try{} @finally{} {} __block __typeof__(object) block##_##object = object; #endif #endif #endif #ifndef strongify #if DEBUG #if __has_feature(objc_arc) #define strongify(object) autoreleasepool{} __typeof__(object) object = weak##_##object; #else #define strongify(object) autoreleasepool{} __typeof__(object) object = block##_##object; #endif #else #if __has_feature(objc_arc) #define strongify(object) try{} @finally{} __typeof__(object) object = weak##_##object; #else #define strongify(object) try{} @finally{} __typeof__(object) object = block##_##object; #endif #endif #endif ARC和MRC环境下关于防止block内部self循环引用的问题