Block使有注意点
Block使有注意点
在ios推出block后,apple非常推荐开发者使用。但是如果使用不当,可能会出现内存问题。
可以添加如下宏:
#ifndef weakify #if __has_feature(objc_arc) #define weakify( x ) \ _Pragma("clang diagnostic push") \ _Pragma("clang diagnostic ignored \"-Wshadow\"") \ autoreleasepool{} __weak __typeof__(x) __weak_##x##__ = x; \ _Pragma("clang diagnostic pop") #else #define weakify( x ) \ _Pragma("clang diagnostic push") \ _Pragma("clang diagnostic ignored \"-Wshadow\"") \ autoreleasepool{} __block __typeof__(x) __block_##x##__ = x; \ _Pragma("clang diagnostic pop") #endif #endif #ifndef strongify #if __has_feature(objc_arc) #define strongify( x ) \ _Pragma("clang diagnostic push") \ _Pragma("clang diagnostic ignored \"-Wshadow\"") \ try{} @finally{} __typeof__(x) x = __weak_##x##__; \ _Pragma("clang diagnostic pop") #else #define strongify( x ) \ _Pragma("clang diagnostic push") \ _Pragma("clang diagnostic ignored \"-Wshadow\"") \ try{} @finally{} __typeof__(x) x = __block_##x##__; \ _Pragma("clang diagnostic pop") #endif #endif
使用时:
@weakify(self); self.block = ^{ @strongify(self); NSLog(@"AViewControllerAViewController %@",self); };
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