Question

I have the following function

- (void)loginWithCompletionBlock:(void (^)(BOOL))completion

How do I call it? How do I pass a BOOL as a block? I’ve tried several ways and I don’t seem to understand how this works.

Answer 1

You’re not passing “a BOOL as a block”, you’re passing a block that will later be passed a BOOL.

[thingy loginWithCompletionBlock:^(BOOL didSomethingInteresting){
    // Your code here, using didSomethingInteresting, such as:
    if( didSomethingInteresting ){
        // Do something even more interesting
    }
    else {
        // Do something boring
    }
}];

loginWithCompletionBlock: is presumably going to go off and try to log in to some service. When the attempt has ended, either in success or failure, your block, which is a piece of executable code, will be run, and will be passed a BOOL value by loginWithCompletionBlock:

Incidentally, the name of the BOOL can be whatever you like, although usually the API you’re using will give it a name (such as success) to indicate its meaning.