Animating UIView shape and its content

Question

In an iPhone app how would you animate the shape of an UIView, for example changing from a rectangle into a circle?

I've tried with:

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"path"];
animation.duration = 20.0;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.fromValue = (__bridge_transfer id)aPath;
animation.toValue = (__bridge_transfer id)anotherPath;
[myShapeLayer addAnimation:animation forKey:@"animatePath"];

where myShapeLayer is an instance of CAShapeLayer and aPath and anotherPath CGMutablePathRef. It works but the view content is not animated as well.

I need to transform a view into a circle and then let it shrink until it disappears.

Answer 1

Try something like this: Where animeView is your UIView

CABasicAnimation *anim1 = [CABasicAnimation animationWithKeyPath:@"cornerRadius"];
anim1.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
anim1.fromValue = [NSNumber numberWithFloat:0.0f];
anim1.toValue = [NSNumber numberWithFloat:50.0f]; //Half the size of your UIView
anim1.duration = 2.0;
[animeView.layer addAnimation:anim1 forKey:@"cornerRadius"];

[UIView animateWithDuration:10.0 delay:2 options:UIViewAnimationOptionCurveEaseInOut animations:^{

    animeView.layer.cornerRadius = 50; //Half the size of your UIView
    CGRect reduceRect = animeView.frame;
    reduceRect.size.height = 0;
    reduceRect.size.width = 0;
    [animeView setFrame:reduceRect];
    animeView.alpha = 0;
                    } completion:nil];

Might need some tweaks for you here and there ;-)

EDIT 1:

Ok so how about using two UIView animations? The first will shrink, strech and move your view. The second will shrink, slink and remove your view.

[UIView animateWithDuration:2.0 delay:0.5 options:UIViewAnimationOptionCurveEaseIn animations:^{

    CGRect moveRect = animeView.frame;
    moveRect.origin.x = 0;
    moveRect.origin.y = (animeView.center.y -20); //Half the size of height reduction
    moveRect.size.height = (animeView.bounds.size.height -40); // height reduction
    moveRect.size.width = (animeView.bounds.size.width +20);
    [animeView setFrame:moveRect];

} completion:^(BOOL finished){
    [UIView animateWithDuration:2.0 delay:0 options:UIViewAnimationOptionCurveEaseIn animations:^{
        CGRect reduceRect = animeView.frame;
        reduceRect.size.height = 0;
        reduceRect.size.width = 0;
        reduceRect.origin.x = -50;
        reduceRect.origin.y = animeView.center.y;
        animeView.alpha = 0;
        [animeView setFrame:reduceRect];
    } completion:nil];

}];

EDIT 2:

A answer to you question in the comments:

You can execute animations simultaneous by creating a CAAnimationGroup. Also I'm using a image to create the resize of content effect. Example:

//Create a screenshot of your UIView... Still animeView in this example
UIGraphicsBeginImageContext(animeView.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[animeView.layer renderInContext:context];
UIImage *screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

//Add the image as subview:
UIImageView * imageView = [[UIImageView alloc] initWithImage:screenShot];
[animeView addSubview:imageView];

//A cornerRadius animation:
CABasicAnimation *radiusAni = [CABasicAnimation animationWithKeyPath:@"cornerRadius"];
radiusAni.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
radiusAni.fromValue = [NSNumber numberWithFloat:0.0f];
radiusAni.toValue = [NSNumber numberWithFloat:50.0f];

//A stretch animation:
CABasicAnimation *stretchAni = [CABasicAnimation animationWithKeyPath:@"transform.scale.x"];
stretchAni.fromValue = [NSNumber numberWithDouble:1];
stretchAni.toValue = [NSNumber numberWithDouble:(animeView.frame.size.width+100)/animeView.frame.size.width];

//A slide animation:
CABasicAnimation *slideAni = [CABasicAnimation animationWithKeyPath:@"transform.translation.x"];
slideAni.fromValue = [NSNumber numberWithDouble:0];
slideAni.toValue = [NSNumber numberWithDouble:-100];

//A opacity animation:
CABasicAnimation *opacityAni = [CABasicAnimation animationWithKeyPath:@"opacity"];
opacityAni.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
opacityAni.fromValue = [NSNumber numberWithFloat:1];
opacityAni.toValue = [NSNumber numberWithFloat:0];

//The animationgroup
CAAnimationGroup *animGroup = [CAAnimationGroup animation];

//Add them to the group:
[animGroup setAnimations:[NSArray arrayWithObjects:radiusAni, opacityAni, slideAni, stretchAni, nil]];
//Set the properties:
[animGroup setDuration:3.0];
[animGroup setRemovedOnCompletion:NO];
[animGroup setFillMode:kCAFillModeForwards];

//Execute all the animations in the group:
[animeView.layer addAnimation:animGroup forKey:nil];

Then you'll have 4 animations executing at the same time and the resize of the content when stretching, shrinking or whatever you plan to do ;-)