Question

I wrote a demo application that works perfectly on the simulator, but when I put it on an actual device, the dice skip around. Here is a video as an example. After I restart the app, the animations are fine. The errors happened about 1 minute of repeatadly hitting the roll button.

http://youtu.be/N1k1QPa1brg

The code is all live at:

https://github.com/rnystrom/MartionDemo

How I make the animation in the dice object:

CCAnimation *anim = [CCAnimation animationWithFrames:frames delay:delay];
if(self.sprite){
    // Animate the sprite
    [self.sprite runAction:[CCAnimate actionWithAnimation:anim restoreOriginalFrame:NO]];
}

The rolling function:

-(void)roll
{
    // Array that contains the new positions of dice
    // Predetermine the position, check if that will be on top of other dice
    NSMutableArray* checkPos = [NSMutableArray array];

    for(Dice* d in rollDiceArray){
        [d resetPosition];    

        // Select a random position within bounds
        NSInteger x = arc4random() % 600 + 50;
        NSInteger y = arc4random() % 600 + 150;
        CGPoint location = CGPointMake(x, y);

        // Check if die will touch other dice
        while (! [self checkPositionWithPoint:location array:checkPos]) {
            // If position overlaps another die, get a new position
            // PROBLEM: This is O(infinity)!
            x = arc4random() % 600 + 50;
            y = arc4random() % 600 + 150;
            location = CGPointMake(x, y);
        }

        // If position does not overlap, add it to array of positions to be checked
        [checkPos addObject:[NSArray arrayWithObjects:[NSNumber numberWithInteger:x], [NSNumber numberWithInteger:y], nil]];

        // Animate the dice to a position
        // Addition in the switch is for some randomness and correcting the animation's timing offset
        NSInteger numberFrames;
        float frameRate;
        float mod = (float)(arc4random() % 60) / 100;
        switch (d.fileNum) {
            case 0:
                numberFrames = kRayFrames;
                frameRate = numberFrames/24 + mod;
                break;
            case 1:
                numberFrames = kRayFrames;
                frameRate = numberFrames/24 + mod - 0.4;
                break;
            case 2:
                numberFrames = kTankFrames;
                frameRate = numberFrames/24 + mod + 0.2;
                break;
            case 3:
                numberFrames = kChickenFrames;
                frameRate = numberFrames/24 + mod;
                break;
            case 4:
                numberFrames = kCowFrames;
                frameRate = numberFrames/24 + mod + 0.2;
                break;
            case 5:
                numberFrames = kHumanFrames;
                frameRate = numberFrames/24;
                break;
            default:
                break;
        }

        id action = [CCMoveTo actionWithDuration:frameRate position:location];
        id ease = [CCEaseOut actionWithAction:action rate:4.0];
        [d.sprite runAction:ease];
    }
}

Answer 1

This turned out to be a performSelector:afterDelay: issue. I resolved it by adding some padding time to my delay so things did not happen simultaneously.

I also put in a block so that action can only be made after the animations were finished. There seems to be some sort of issue when interrupting a CCMoveTo-esque animation.