How to write an Objective-C Completion Block

Question

I\'m in a situation where need to call a class method from my view controller, have it do it\'s thing, but then perform some actions ONLY AFTER the class method has complete

Answer 1

Simple Completion block

    // Completion block method
    -(void)myMethod:(void (^)(void))completion {
        NSLog(@"iPhone");
        completion();
        NSLog(@"iPod");
    }

   // Calling completion block method
    - (void)viewDidLoad {
        [super viewDidLoad];

        [self myMethod:^{
           NSLog(@"iPad");
        }];
    }

  // output
  iPhone
  iPad
  iPod