[iOS]Ojbective C async call sample

1. Define block method:

typedef void (^MyTestBlock)(void);

MyTestBlock myBlock = ^void() {

    // your implementation

}];

2. Consumer

[[NSNotificationCenter defaultCenter] addObserverForName:@"key" object:nil queue:nil usingBlock:^(NSNotification *note) {

            myBlock();

        }];

3. Trigger

[[NSNotificationCenter defaultCenter] postNotificationName:@"key" object:nil userInfo:nil];