如何从特定锚点旋转图像

Question

我想用此代码旋转图像为pic1。我在正要寻找的图像下方放置了一张图像。我不想将我想从矩形左下角旋转的整个图像旋转90度。您可以在绿色圆圈中清楚地看到我在说什么。旋转应在按钮功能中进行。

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(){



}
}

Answer 1

您可以扩展uiview来设置锚点：

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;
    }
}

然后在viewDidLoad中设置锚点：

// set anchor point
self.myView.setAnchorPoint(anchorPoint: CGPoint(x: 0.5, y: 1))

通话立即旋转

func Rotate(){

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

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

        })
        rotation.startAnimation()

    }