Question

Hi I’m new to using blocks in Objective-C

What I think I want is the following:

- (void) iNeedAToken {

  NSString *token = [self theMethodThatShouldReturnTheToken];

}

- (NSString) theMethodThatShouldReturnTheToken {

  [myAwesomeAsyncMethod success:^(id JSON) {

        NSString *token = [JSON objectForKey:@"FOO"];
        return token;

    }]

}

Is this possible? Or is this the wrong logic all together?

Thanks!

Answer 1

You’re mixing async with synchronous code. You’re theMethodThatShouldReturnTheToken already returned (you’re missing a return value) before the block passed to success finishes.

Best bet would be to continue your process from the success block.

- (void) tokenRequestContext1
{
    [self requestToken:^(NSString *token) {
        // do something with token
    }];
}

- (void) requestToken:(void(^)(NSString *))tokenBlock
{
    [myAwesomeAsyncMethod success:^(id JSON) {
        NSString *token = [JSON objectForKey:@"FOO"];
        if (tokenBlock) {
            tokenBlock(token);
        }
    }];
}

You start by calling requestToken. This will start the async request for your token. Some time might pass, but eventually doSomethingWithToken will be called where you can use the received token.