UIView animate - Rotate and scale up, then rotate and scale down - ios

Question

I have a subclassed imageview that I'd like to fade in, scale up, and rotate, then continue rotating while scaling back down and fading out.
I am using a UIView animate block with a completion handler to handle the shrinking back down.
The problem is it's not a fluid animation. Before the completion handler runs, the animation stops before running again. I need it to be one nice "swoop" of an animation.
Code below:
let duration: TimeInterval = 3.0
let rotate = CGAffineTransform(rotationAngle: CGFloat(Double.pi))
UIView.animate(withDuration: duration * 3, delay: 0, options: [.curveLinear], animations: {
// initial transform
self.alpha = 0
self.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
// initial spin for duration of animaton
UIView.animate(withDuration: duration * 3, delay: 0.0, options: [.curveLinear], animations: {
self.transform = rotate
}, completion: nil)
// scaling and fading
UIView.animate(withDuration: duration, delay: 0, options: [.curveLinear], animations: {
UIView.setAnimationRepeatCount(3)
self.transform = self.transform.scaledBy(x: 0.8, y: 0.8)
self.alpha = 1
}) { (true) in
UIView.animate(withDuration: duration, animations: {
UIView.setAnimationRepeatCount(3)
self.transform = self.transform.scaledBy(x: 0.1, y: 0.1)
self.alpha = 0
})
}
}, completion: nil)
How can I get the animation to rotate the entire time while fading in and scaling up before scaling back down and fading out? The entire animation should last 3 seconds, and repeat 3 times. Thanks.

Answer 1

For your modified request I am expanding what you already saw using the block animations. As some have said, key frame animations may be better, regardless, here is the thought.
Create an animation that rotates the entire time by transforming the view.
Create another animation that does the scaling and fading based off the current transform (which is rotating). In this pass, I just created some variable to allow you to customize (and repeat) portions of the animation. I broke some things out to be clear and know I could refactor to write thing even more concise.
Here is the code
import UIKit
class OrangeView: UIView {
override func layoutSubviews() {
super.layoutSubviews()
let duration: TimeInterval = 9.0
self.transform = CGAffineTransform.identity
// initial transform
self.alpha = 1
self.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
// start rotation
rotate(duration: duration)
// scaling and fading
scaleUpAndDown(desiredRepetitions: 3, initalDuration: duration)
}
func rotate(duration: TimeInterval) {
UIView.animate(withDuration: duration/2.0,
delay: 0.0,
options: [.curveLinear], animations: {
let angle = Double.pi
self.transform = self.transform.rotated(by: CGFloat(angle))
}, completion: {[weak self] finished in
guard let strongSelf = self else {
return
}
if finished &&
strongSelf.transform != CGAffineTransform.identity {
strongSelf.rotate(duration: duration)
} else {
// rotation ending
}
})
}
func scaleUpAndDown(timesRepeated: Int = 0, desiredRepetitions: Int, initalDuration: TimeInterval) {
guard timesRepeated < desiredRepetitions,
desiredRepetitions > 0, initalDuration > 0 else {
self.transform = CGAffineTransform.identity
return
}
let repeatedCount = timesRepeated + 1
let scalingDuration = initalDuration/2.0/Double(desiredRepetitions)
UIView.animate(withDuration: scalingDuration,
delay: 0.0,
animations: {
let desiredOriginalScale: CGFloat = 0.8
let scaleX = abs(CGAffineTransform.identity.a / self.transform.a) * desiredOriginalScale
let scaleY = abs(CGAffineTransform.identity.d / self.transform.d) * desiredOriginalScale
self.transform = self.transform.scaledBy(x: scaleX, y: scaleY)
self.alpha = 1
}) { (true) in
UIView.animate(withDuration:scalingDuration,
delay: 0.0,
animations: {
let desiredOriginalScale: CGFloat = 0.1
let scaleX = abs(CGAffineTransform.identity.a / self.transform.a) * desiredOriginalScale
let scaleY = abs(CGAffineTransform.identity.d / self.transform.d) * desiredOriginalScale
self.transform = self.transform.scaledBy(x: scaleX, y: scaleY)
self.alpha = 0
}) { finshed in
self.scaleUpAndDown(timesRepeated: repeatedCount, desiredRepetitions: desiredRepetitions, initalDuration: initalDuration);
}
}
}
}
Finally here is another animated gif

Answer 2

I see the slight stutter in rotation at the start of the onCompletion.
I created a reduction with your code (shown below in the Blue View) and a variation in the Orange View. This was taken from the simulator and turned into an animated GIF, so speed is slowed down. The Orange View continues to spin as the complete transform just scales down.
This is the code for the layoutSubviews() for the Orange View
override func layoutSubviews() {
super.layoutSubviews()
let duration: TimeInterval = 3.0
let rotate = CGAffineTransform(rotationAngle: CGFloat(Double.pi))
// initial transform
self.alpha = 0
self.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
// initial spin for duration of animaton
UIView.animate(withDuration: duration,
delay: 0.0,
options: [.curveLinear],
animations: {
self.transform = rotate;
},
completion: nil)
// scaling and fading
UIView.animate(withDuration: duration/2.0, animations: {
self.transform = self.transform.scaledBy(x: 0.8, y: 0.8)
self.alpha = 1
}) { (true) in
UIView.animate(withDuration: duration/2.0, animations: {
self.transform = self.transform.scaledBy(x: 0.1, y: 0.1)
self.alpha = 0
})
}
}

Answer 3

Try using CGAffineTransformConcat()
CGAffineTransform scale = CGAffineTransformMakeScale(0.8, 0.8);
self.transform = CGAffineTransformConcat(CGAffineTransformRotate(self.transform, M_PI / 2), scale);