不影响方法单独延迟返回值

Question

能不能实现单独延迟返回值，不对整个方法造成影响？

-(CGFloat)getValue{
// code implementation
return floatvalue; // return float value with some delay.
}

Answer 1

使用block回调值时延迟

- (void)ayncGetValue:(void(^)(id value))returnBlock {

  dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, 10.f * NSEC_PER_SEC); // delay 10 seconds
  dispatch_after(popTime, dispatch_get_main_queue(), ^{
    returnBlock(@"hello block");
  });
}
// Usage
[obj ayncGetValue:^(id value) {
  // continue  
}];