Changing UIView rotation will change it's frame size. How to keep frame size after rotating? - swift

Question

I'm rotating UIView by the UIRotationGestureRecognizer but I have a problem, The rotated UIView's frame size will be changed on rotation.
targetView = UIView(frame: CGRect(x: self.view.center.x, y: self.view.center.y , width: 100, height: 100))
targetView.backgroundColor = .red
targetView.isUserInteractionEnabled = true
self.view.addSubview(targetView)
targetView.center = self.view.center
let rotate = UIRotationGestureRecognizer(target: self, action: #selector(rotatedView))
targetView.addGestureRecognizer(rotate)
Here is the rotate function:
#objc func rotatedView(_ sender: UIRotationGestureRecognizer) {
var originalRotation = CGFloat()
if sender.state == .began {
sender.rotation = lastRotation
originalRotation = sender.rotation
print("TargetView Frame Size: [START ROTATE] ", self.targetView.frame.size)
print("TargetView Bounse Size: [START ROTATE] ", self.targetView.bounds)
} else if sender.state == .changed {
let newRotation = sender.rotation + originalRotation
sender.view?.transform = CGAffineTransform(rotationAngle: newRotation)
print("TargetView Frame Size: [ROTATETING] ", self.targetView.frame.size)
print("TargetView Bounse Size: [ROTATING ROTATE] ", self.targetView.bounds)
}
}
Size will be changed:
TargetView Frame Size: [START ROTATE] (100.0, 100.0)
TargetView Frame Size: [ROTATETING] (110.564206726133, 110.564206726133)
How to keep frame size after rotating just like Start Rotating?!
EDIT:
I have these gestures together: Rotate, Resize, Move.
Move is working well, but Rotate is changing size. I can use bounds here but If I resize too, the bounds is not useful anymore.

Answer 1

You need the scaled but non-rotated view size. You can compute that from the bounds.size of the view and the transform.
Example
let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 150))
// Scale view by 3X horizontally and by 4X vertically and
// rotate by 45 degrees
view.transform = CGAffineTransform(scaleX: 3, y: 4).rotated(by: 45.0 / 180.0 * .pi)
let transform = view.transform
// Find the angle, print it in degrees
let angle = atan2(-transform.c, transform.a)
print(angle * 180.0 / .pi) // 44.99999999999999
// Find scaleX and scaleY
let scaleX = transform.a * cos(angle) - transform.c * sin(angle)
let scaleY = transform.d * cos(angle) + transform.b * sin(angle)
print(scaleX) // 3.0
print(scaleY) // 4.0
print(view.frame.size) // (530.3300858899106, 707.1067811865476)
print(view.bounds.size) // (100.0, 150.0)
let adjustedSize = CGSize(width: view.bounds.size.width * scaleX, height: view.bounds.size.height * scaleY)
// print non-rotated but scaled size
print(adjustedSize) // (300.0, 600.0)
Here it is as a handy extension that will work for views that are scaled, rotated, and translated (moved):
extension CGAffineTransform {
var angle: CGFloat { return atan2(-self.c, self.a) }
var angleInDegrees: CGFloat { return self.angle * 180 / .pi }
var scaleX: CGFloat {
let angle = self.angle
return self.a * cos(angle) - self.c * sin(angle)
}
var scaleY: CGFloat {
let angle = self.angle
return self.d * cos(angle) + self.b * sin(angle)
}
}
Now, if you have a UIView:
let angle = view.transform.angleInDegrees
let scaleX = view.transform.scaleX
let scaleY = view.transform.scaleY
let adjustedSize = CGSize(width: view.bounds.size.width * scaleX, height: view.bounds.size.height * scaleY)