参考链接：https://www.jianshu.com/p/62ea7bb79b58

OC Block 定义
作为参数
* (void)pingSingleWithHost:(NSString *)host block:(void(^ _Nullable)(BOOL, NSString *, NSUInteger))block;
* 
作为属性1
@property (copy) void(^pingStrFinishBlock)(BOOL success, NSString *host, NSUInteger finishCount);
作者：glView


作为属性2
typedef void (^CancleBlock)(void);
///取消回调
@property (nonatomic, copy) CancleBlock cancleBlock;