(void(^)(POPAnimation *anim, BOOL finished)) block
blcok寫在了屬性中.
@property (nonatomic,strong) void(^monitoringBlock)(CMTime time);
在多線程環(huán)境下（block中的weakSelf有可能被析構(gòu)的情況下）琅催，需要先將self轉(zhuǎn)為strong指針，避免在運(yùn)行到某個(gè)關(guān)鍵步驟時(shí)self對象被析構(gòu)攒读。
Paste_Image.png
__weak __typeof(self)weakSelf = self;
AFNetworkReachabilityStatusBlock callback = ^(AFNetworkReachabilityStatus status) {
__strong __typeof(weakSelf)strongSelf = weakSelf;
strongSelf.networkReachabilityStatus = status;
if (strongSelf.networkReachabilityStatusBlock)
{
strongSelf.networkReachabilityStatusBlock(status);
}
};
