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