Get rotated rectangle UIView corners' coordinates iOS - ios

Question

I'm trying to find a rotated rectangle UIView's four corners' coordinates.
I think one way I can do is to use recognizer.rotation, find the rotated angle then calculate the origins. But that requires some geometry calculation.
- (IBAction)handlePan:(UIRotationGestureRecognizer*)recognizer {
NSLog(#"Rotation in degrees since last change: %f", [recognizer rotation] * (180 / M_PI));
recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
NSLog(#"%#",recognizer);
recognizer.rotation = 0;
NSLog(#"bound is %f and %f, frame is %f and %f, %f and %f.",recognizer.view.bounds.size.width,recognizer.view.bounds.size.height, recognizer.view.frame.size.width,recognizer.view.frame.size.height, recognizer.view.frame.origin.x, recognizer.view.frame.origin.y);
}
I'm just wondering if there are any other easier ways to get the coordinates?
Thanks!
EDIT:
Looks like we have a great answer here(see answer below). I have managed to calculate the corners through a stupid way -- using rotation angle and geometry. It works but not easy and light. I'm sharing my code here just in case some one may want to use it(Even though I doubt it.)
float r = 100;
NSLog(#"radius is %f.",r);
float AAngle = M_PI/3+self.rotatedAngle;
float AY = recognizer.view.center.y - sin(AAngle)*r;
float AX = recognizer.view.center.x - cos(AAngle)*r;
self.pointPADA = CGPointMake(AX, AY);
NSLog(#"View Center is (%f,%f)",recognizer.view.center.x,recognizer.view.center.y);
NSLog(#"Point A has coordinate (%f,%f)",self.pointPADA.x,self.pointPADA.y);
float BAngle = M_PI/3-self.rotatedAngle;
float BY = recognizer.view.center.y - sin(BAngle)*r;
float BX = recognizer.view.center.x + cos(BAngle)*r;
self.pointPADB = CGPointMake(BX, BY);
NSLog(#"Point B has coordinate (%f,%f)",BX,BY);
float CY = recognizer.view.center.y + sin(AAngle)*r;
float CX = recognizer.view.center.x + cos(AAngle)*r;
self.pointPADC = CGPointMake(CX, CY);
NSLog(#"Point C has coordinate (%f,%f)",CX,CY);
float DY = recognizer.view.center.y + sin(BAngle)*r;
float DX = recognizer.view.center.x - cos(BAngle)*r;
self.pointPADD = CGPointMake(DX, DY);
NSLog(#"Point D has coordinate (%f,%f)",DX,DY);

Answer 1

Here's my solution though I wonder if there's a more succinct way:
CGPoint originalCenter = CGPointApplyAffineTransform(theView.center,
CGAffineTransformInvert(theView.transform));
CGPoint topLeft = originalCenter;
topLeft.x -= theView.bounds.size.width / 2;
topLeft.y -= theView.bounds.size.height / 2;
topLeft = CGPointApplyAffineTransform(topLeft, theView.transform);
CGPoint topRight = originalCenter;
topRight.x += theView.bounds.size.width / 2;
topRight.y -= theView.bounds.size.height / 2;
topRight = CGPointApplyAffineTransform(topRight, theView.transform);
CGPoint bottomLeft = originalCenter;
bottomLeft.x -= theView.bounds.size.width / 2;
bottomLeft.y += theView.bounds.size.height / 2;
bottomLeft = CGPointApplyAffineTransform(bottomLeft, theView.transform);
CGPoint bottomRight = originalCenter;
bottomRight.x += theView.bounds.size.width / 2;
bottomRight.y += theView.bounds.size.height / 2;
bottomRight = CGPointApplyAffineTransform(bottomRight, theView.transform);

Answer 2

Checked answer in Swift
struct ViewCorners {
private(set) var topLeft: CGPoint!
private(set) var topRight: CGPoint!
private(set) var bottomLeft: CGPoint!
private(set) var bottomRight: CGPoint!
private let originalCenter: CGPoint
private let transformedView: UIView
private func pointWith(multipliedWidth: CGFloat, multipliedHeight: CGFloat) -> CGPoint {
var x = originalCenter.x
x += transformedView.bounds.width / 2 * multipliedWidth
var y = originalCenter.y
y += transformedView.bounds.height / 2 * multipliedHeight
var result = CGPoint(x: x, y: y).applying(transformedView.transform)
result.x += transformedView.transform.tx
result.y += transformedView.transform.ty
return result
}
init(view: UIView) {
transformedView = view
originalCenter = view.center.applying(view.transform.inverted())
topLeft = pointWith(multipliedWidth:-1, multipliedHeight:-1)
topRight = pointWith(multipliedWidth: 1, multipliedHeight:-1)
bottomLeft = pointWith(multipliedWidth:-1, multipliedHeight: 1)
bottomRight = pointWith(multipliedWidth: 1, multipliedHeight: 1)
}
}
Then create struct instance and take transformed rect corners new points.
let view = UIView(frame: CGRect(x: 40, y: 20, width: 100, height: 50))
view.transform = .init(rotationAngle: .pi / 4)
let corners = ViewCorners(view: view)
print(corners.topLeft,
corners.topRight,
corners.bottomLeft,
corners.bottomRight,
separator: "\n")

Answer 3

Using Swift 4, We can get the bounds of rotated view by simple way.
let transformedBounds = view.bounds.applying(view.transform)