Creating a simple Simon clone: How to wait between updates?

Question

I'm learning Cocoa/Objective-C/iPhone SDK, and as a simple project to apply what I've learned, I wanted to create a simple version of the Simon game of old. Four colored buttons, you're shown a sequence (Red, Green, Blue, Red, etc.) and you have to repeat the sequence back.

I believe I have most of it figured out, save one piece: showing the sequence to the user. Specifically, how to implement the delay between highlighting the button & setting it back to normal after 200ms.

If I sleep in the main run loop, the update doesn't happen properly (even if I explicitly call setNeedsDisplay). If I spawn off a new thread, things get complicated quickly as my class method needs to refer back to UI elements (instant variables).

Any advice?

Answer 1

Read the docs for the Core Animation framework.

Answer 2

"simon" is a very simple MIDI sequencer. therefore I would highly suggest looking into the CoreAudio Framework, in particular the real-time-clock functionality.

Answer 3

You can use the +setAnimationStartDate: method on UIView to set up some animations to do this. To ensure that no one presses your buttons during the animation, call -[UIApplication beginIgnoringInteractionEvents] at the start of your animations and -[UIApplication endIgnoringInteractionEvents] at the end.

A written-in-the-text-field example of what I’m talking about:

[[UIApplication sharedApplication] beginIgnoringInteractionEvents];
button1.highlighted = YES;

[UIView beginAnimations:@"" context:nil];
[UIView setAnimationStartDate: CFAbsoluteTimeGetCurrent() + 0.2];
[UIView setAnimationsEnabled:NO];
button1.highlighted = NO;
[UIView commitAnimations];

[UIView beginAnimations:@"" context:nil];
[UIView setAnimationStartDate: CFAbsoluteTimeGetCurrent() + 0.25];
[UIView setAnimationsEnabled:NO];
button2.highlighted = YES;
[UIView commitAnimations];

// etc.

[[UIApplication sharedApplication] performSelector:@selector(endIgnoringInteractionEvents) withObject:nil afterDelay:yourTotalDelay];

Answer 4

gerry3 gives an answer here:

http://stackoverflow.com/questions/1672060/how-can-i-show-a-sequence-of-buttons-highlighting