Custom completion block for my own method

Question

I just opened the completion blocks:

completion:^(BOOL finished){ }]; 

What do I need to do so that my own method takes a completion block?

Answer 1

1) Define your own completion block,

 typedef void(^myCompletion)(BOOL); 

2) Create a method that takes your completion block as a parameter,

 -(void) myMethod:(myCompletion) compblock{ //do stuff compblock(YES); } 

3) This is how you use it,

 [self myMethod:^(BOOL finished) { if(finished){ NSLog(@"success"); } }]; 

Answer 2

You define the block as a custom type:

 typedef void (^ButtonCompletionBlock)(int buttonIndex); 

Then use it as an argument to the method:

 + (SomeButtonView*)buttonViewWithTitle:(NSString *)title cancelAction:(ButtonCompletionBlock)cancelBlock completionAction:(ButtonCompletionBlock)completionBlock 

When calling this code, it is like any other block:

 [SomeButtonView buttonViewWithTitle:@"Title" cancelAction:^(int buttonIndex) { NSLog(@"User cancelled"); } completionAction:^(int buttonIndex) { NSLog(@"User tapped index %i", buttonIndex); }]; 

If it's time to start the block, just call completionBlock() (where completionBlock is the name of your local copy of the block).

Answer 3

Block variables are similar in syntax to function pointers in C.

Because the syntax is ugly, they are often typed, however they can also be declared as usual.

 typedef void (^MyFunc)(BOOL finished); - (void)myMethod:(MyFunc)func { } 

See this answer for non typedef:

Declare a block method parameter without using typedef