How to synchronously animate a UIView and a CALayer

Question

To illustrate this question, I gisted a very small Xcode project on Github (two classes, 11kb download). Have a look at the gist here or use git clone git@gist.githu

Answer 1

If you want David Rönnqvist's snippet in Swift 3.0, here you have it:

    CATransaction.begin()
    CATransaction.setAnimationDuration(1.0)
    CATransaction.setAnimationTimingFunction(CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut))

    // Layer animation
    let myAnimation = CABasicAnimation(keyPath: "frame");
    myAnimation.toValue = NSValue(cgRect: myNewFrame)
    myAnimation.fromValue = NSValue(cgRect: myLayer.frame)

    myLayer.frame = myNewFrame
    myLayer.add(myAnimation, forKey: "someKeyForMyAnimation")

    // Outer animation
    let outerAnimation = CABasicAnimation(keyPath: "frame")
    outerAnimation.toValue = NSValue(cgRect: myNewOuterFrame)
    outerAnimation.fromValue = NSValue(cgRect: outerView.frame)

    outerView.layer.frame = myNewOuterFrame
    outerView.layer.add(outerAnimation, forKey: "someKeyForMyOuterAnimation")

    CATransaction.commit()

Answer 2

I'm assuming that you got the end position correct and that after the animation that the view and the layer are aligned. That has nothing to do with the animation, just geometry.

---

When you change the property of a CALayer that isn't the layer of a view (like in your case) it will implicitly animate to its new value. To customize this animation you could use an explicit animation, like a basic animation. Changing the frame in a basic animation would look something like this.

CABasicAnimation *myAnimation = [CABasicAnimation animationWithKeyPath:@"frame"];
[myAnimation setToValue:[NSValue valueWithCGRect:myNewFrame]];
[myAnimation setFromValue:[NSValue valueWithCGRect:[myLayer frame]]];
[myAnimation setDuration:1.0];
[myAnimation setTimingFunction:[CAMediaTimingFuntion functionWithName: kCAMediaTimingFunctionEaseOut]];

[myLayer setFrame:myNewFrame];
[myLayer addAnimation:myAnimation forKey:@"someKeyForMyAnimation"];

If the timing function and the duration of both animations are the same then they should stay aligned.

Also note that explicit animations doesn't change the value and hat you have to both add the animation and set the new value (like in the sample above)

---

Yes, there are a number of ways to achieve the same effect. One example is having the view and the layer be subviews of the same subview (that in turn is a subview of the outer frame).

Edit

You can't easily group the UIView-animation with an explicit animation. Neither can you use an animation group (since you are applying them to different layers) but yo can use a CATransaction:

[CATransaction begin];
[CATransaction setAnimationDuration:1.0];
[CATransaction setAnimationTimingFunction:[CAMediaTimingFuntion functionWithName: kCAMediaTimingFunctionEaseOut]];

// Layer animation
CABasicAnimation *myAnimation = [CABasicAnimation animationWithKeyPath:@"frame"];
[myAnimation setToValue:[NSValue valueWithCGRect:myNewFrame]];
[myAnimation setFromValue:[NSValue valueWithCGRect:[myLayer frame]]];

[myLayer setFrame:myNewFrame];
[myLayer addAnimation:myAnimation forKey:@"someKeyForMyAnimation"];

// Outer animation
CABasicAnimation *outerAnimation = [CABasicAnimation animationWithKeyPath:@"frame"];
[outerAnimation setToValue:[NSValue valueWithCGRect:myNewOuterFrame]];
[outerAnimation setFromValue:[NSValue valueWithCGRect:[outerView frame]]];

[[outerView layer] setFrame:myNewOuterFrame];
[[outerView layer] addAnimation:outerAnimation forKey:@"someKeyForMyOuterAnimation"];

[CATransaction commit];