使用方法很简单。
///创建一个异步执行block 一个key对应一个block
NSString *queueKey = NSStringFromSelector(_cmd);
[NSObject imy_asyncBlock:^{
///do something
} onQueue:dispatch_get_global_queue(0, 0) afterSecond:2 forKey:queueKey];
///该key 是否还有未执行的Block
BOOL hasContain = [NSObject imy_hasAsyncBlockForKey:queueKey];
///取消该block
[NSObject imy_cancelBlockForKey:queueKey];