Question

I would like to know what is the name of the functionality that is used in the Ipad’s Music folder, where when an album folder is clicked, details regarding that album pops up in an animated view.

I tried using presentModelViewController but its functionality is different.

It would be great if someone could help me out.

Answer 1

I just managed to get sth. like this to work using CoreAnimation / QuartzCore Framework…
be sure to

#import <QuartzCore/QuartzCore.h>

when you want to animate, use CATransform3Dand the poorly documented CATransform3D.m34 property. this will do the first half of the animation (assuming 200×200<->450×450 with 180° rotation):

[UIView beginAnimations:nil context:NULL];

[UIView setAnimationDuration:0.5];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDelegate:self];
CATransform3D rotationAndPerspectiveTransform = CATransform3DIdentity;
rotationAndPerspectiveTransform.m34 = 1.0 / -1000; // this turns on perspective!
rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, 90.0f * M_PI / 180.0f, 0.0f, 1.0f, 0.0f);
someView.layer.transform = rotationAndPerspectiveTransform;
someView.bounds = CGRectMake(0, 0, 325, 325);

[UIView commitAnimations];

for the second half of the animation, you have to add/remove your view to the hierarchy. this example shows hiding/showing of a view that already exists as a subview of someView, it also makes use of a BOOL isUp instance variable (the first half of the aniation is independent of the isUp-flag!)

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    if (flag) {
        if (isUp) {
            someSubView.hidden = YES; // hide subview
            [UIView beginAnimations:nil context:NULL];

            [UIView setAnimationDuration:0.5];
            [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
            CATransform3D rotationAndPerspectiveTransform = CATransform3DRotate(someView.layer.transform, -90.0f * M_PI / 180.0f, 0.0f, 1.0f, 0.0f);
            someView.layer.transform = rotationAndPerspectiveTransform;
            someView.bounds = CGRectMake(0, 0, 200, 200);

            [UIView commitAnimations];
            isUp = NO;
        } else {
            someSubView.hidden = NO; // Show subview
            [UIView beginAnimations:nil context:NULL];

            [UIView setAnimationDuration:0.5];
            [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
            CATransform3D rotationAndPerspectiveTransform = CATransform3DRotate(someView.layer.transform, 90.0f * M_PI / 180.0f, 0.0f, 1.0f, 0.0f);
            someView.layer.transform = rotationAndPerspectiveTransform;
            someView.bounds = CGRectMake(0, 0, 450, 450);

            [UIView commitAnimations];
            isUp = YES;
        }
    }
}

one last thing: everything in your view will appear mirrored, it might not be the ideal solution, but mirroring back by applying a CGAffineTransform to the subview does the trick:

- (void)viewDidLoad
{
    [super viewDidLoad];
    someSubView.transform = CGAffineTransformMakeScale(-1, 1);
    isUp = NO;
}

i’m alredy a month late with this solution but i hope it helped someone 🙂

i first tried using the animateWithDuration:animations:completion: block-based API but that turned out to lag heavily (no smooth first/second-half animaiton even without touching subviews).