NSTimer with anonymous function / block?

You can make use of dispatch_after if you want to achieve something similar to NSTimer and block execution.

Here is the sample code for the same:

    int64_t delayInSeconds = gameInterval; // Your Game Interval as mentioned above by you

    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);

    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

        // Update your label here. 

    });

Hope this helps.

Objective-C version of @Peter Peng's answer:

_actionDelayTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:[NSBlockOperation blockOperationWithBlock:^{
    NSLog(@"Well this is useless.");
}] selector:@selector(main) userInfo:nil repeats:YES];

A block based timer API exists in Cocoa (as of iOS 10+ / macOS 10.12+) – here's how you can use it from Swift 3 onwards:

Timer(timeInterval: gameInterval, repeats: false) { _ in
    print("herp derp")
}

… or in Objective-C:

[NSTimer scheduledTimerWithTimeInterval:gameInterval repeats:NO block:^(NSTimer *timer) {
    NSLog(@"herp derp");
}];

As noted in a comment, be careful not to use strong self references inside the block to avoid retain cycles (for more info).

If you need to target OS versions older than iOS10, macOS 12, tvOS 10, watchOS 3, you should use one of the other solutions.

You can actually call:

NSTimer.scheduledTimerWithTimeInterval(ti: NSTimeInterval,
                    target: AnyObject, 
                    selector: #Selector, 
                    userInfo: AnyObject?, 
                    repeats: Bool)

Use it like this:

NSTimer.scheduledTimerWithTimeInterval(1, 
                    target: NSBlockOperation(block: {...}), 
                    selector: #selector(NSOperation.main), 
                    userInfo: nil, 
                    repeats: true)