Animation with animation "animation"

Question

I want to use Core Animation to simulate flip clock animations in a Mac application. I currently have three CALayer representing the upper and lower half of a digit, and the third is a flip animation (the solution found in the following article: Creating an iPad flip clock with Core Animation .

The animation of the flip layer is divided into two stages: flipping from the top to the middle of the number, and then from the middle to the bottom. To do this, I use the delegate function, which is called whenever the animation ends:

- (void)animationDidStop:(CAAnimation *)oldAnimation finished:(BOOL)flag
{
    int digitIndex = [[oldAnimation valueForKey:@"digit"] intValue];    
    int currentValue = [[oldAnimation valueForKey:@"value"] intValue];

    NSMutableArray *digit = [digits objectAtIndex:digitIndex];
    CALayer *flipLayer = [digit objectAtIndex:tickerFlip];
    CALayer *bottomLayer = [digit objectAtIndex:tickerBottom];

    if([[oldAnimation valueForKey:@"state"] isEqual:@"top"] && flag) {
        NSLog(@"Top animation finished");

        [CATransaction begin];
        [CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];
        flipLayer.contents = [bottomImages objectAtIndex:currentValue];
        flipLayer.anchorPoint = CGPointMake(0.0, 1.0);
        flipLayer.hidden = NO;
        [CATransaction commit];

        CABasicAnimation *anim = [self generateAnimationForState:@"bottom"];
        [anim setValue:[NSString stringWithFormat:@"%d", digitIndex] forKey:@"digit"];
        [anim setValue:[NSString stringWithFormat:@"%d", currentValue] forKey:@"value"];
        [flipLayer addAnimation:anim forKey:nil];
    } else if([[oldAnimation valueForKey:@"state"] isEqual:@"bottom"] && flag) {
        NSLog(@"Bottom animation finished");

        // Hide our flip layer
        [CATransaction begin];
        [CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];
        bottomLayer.contents = [bottomImages objectAtIndex:currentValue];
        flipLayer.hidden = YES;
        flipLayer.anchorPoint = CGPointMake(0.0, 0.0);
        [CATransaction commit];
    }
}

This delegate function uses a helper function that generates a transform for the flip layer depending on its state:

- (CABasicAnimation *)generateAnimationForState:(NSString *)state
{
    CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"transform"];
    anim.duration = 0.15;
    anim.repeatCount = 1;

    // Check which animation we're doing
    if([state isEqualToString:@"top"]) 
    {
        anim.fromValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(0.0f, 1, 0, 0)];
        anim.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(M_PI/2, 1, 0, 0)];
    } 
    else 
    {
        anim.fromValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(-M_PI/2, 1, 0, 0)];
        anim.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(0.0f, 1, 0, 0)];
    }

    anim.delegate = self;
    anim.removedOnCompletion = NO;

    // Set our animations state
    [anim setValue:state forKey:@"state"];

    return anim;
}

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Answer 1

anim.removedOnCompletion = NO; 

:

anim.fillMode = kCAFillModeForwards;

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