How to rotate a image from a specific anchor point

Question

I want to rotate a image in this code would be pic1. I placed a image below of what I am exactly looking for. I don't want to rotate the entire image I want to rotate from the bottom left corner of the rectangle 90 degrees. You can see specifically what I am talking about in the green circle. The rotation should take place in the button function.

import UIKit

class ViewController: UIViewController {


var pic1 = UIImageView()

var rot = UIButton()


override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.

    pic1.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(pic1)

    rot.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(rot)
    rot.backgroundColor = .blue


    pic1.image = UIImage(named: "badMan.png")

    NSLayoutConstraint.activate(



        [

            pic1.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.50),
            pic1.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 1),
            pic1.topAnchor.constraint(equalTo: view.topAnchor),
            pic1.leadingAnchor.constraint(equalTo: view.leadingAnchor),

            rot.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.50),
            rot.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 1),
            rot.topAnchor.constraint(equalTo: pic1.bottomAnchor),
            rot.leadingAnchor.constraint(equalTo: view.leadingAnchor),





    ])


    self.view.addSubview(pic2)

    rot.addTarget(self, action: #selector(roate), for: .touchDown)
}


@objc func roate(){



}
}

SM Abu Taher Asif · Accepted Answer · 2020-06-04T06:05:14.573

You Can make a extension of uiview to set anchor point :

extension UIView{
    func setAnchorPoint(anchorPoint: CGPoint) {

        var newPoint = CGPoint(x: self.bounds.size.width * anchorPoint.x, y: self.bounds.size.height * anchorPoint.y)
        var oldPoint = CGPoint(x: self.bounds.size.width * self.layer.anchorPoint.x, y: self.bounds.size.height * self.layer.anchorPoint.y)

        newPoint = newPoint.applying(self.transform)
        oldPoint = oldPoint.applying(self.transform)

        var position : CGPoint = self.layer.position

        position.x -= oldPoint.x
        position.x += newPoint.x;

        position.y -= oldPoint.y;
        position.y += newPoint.y;

        self.layer.position = position;
        self.layer.anchorPoint = anchorPoint;
    }
}

Then set anchor point in viewDidLoad:

// set anchor point, below code will set anchor point in the bottom(y) middle (x) of myView
self.myView.setAnchorPoint(anchorPoint: CGPoint(x: 0.5, y: 1))

call rotate now

func Rotate(){

     let   rotation = UIViewPropertyAnimator(duration: 1, curve: .linear, animations: {

        self.myView.transform = self.myView.transform.rotated(by: CGFloat.pi/2)

        })
        rotation.startAnimation()

    }

I used * setAnchorPoint* your code for view rotation about anchor point in swiftUI, but unfortunately did not work, setting anchor point view translate up down from expected position. Do you know solution for setting up anchor point in swiftUI views — Mir, Aug 27 '21 at 11:23
this answer is based on storyboard ui, I will try to add for swiftui — SM Abu Taher Asif, Aug 31 '21 at 05:20

How to rotate a image from a specific anchor point

1 Answers1