De激活将两个对象链接在一起的约束

Question

您在下面的gif中看到的我的快速代码。允许用户选择其中一个图像视图，然后使用滑块来增大或减小该图像视图的大小。问题是当图像视图被移动时，另一个图像视图将跟随它发生，这是不应该发生的。因此，应在首次运行代码但在选择其中一个imageviews之后设置约束。将它们链接在一起的约束应被停用。导致此的行是

** greenMove.leadingAnchor.constraint（equalTo：view.leadingAnchor，常数：0），**

import UIKit

class ViewController: UIViewController {



    var image1Width: NSLayoutConstraint!
    var image1Height: NSLayoutConstraint!
    var image1Width2: NSLayoutConstraint!
    var image1Height2: NSLayoutConstraint!
    var greenMove = UIImageView()
    var slider = UISlider()
    var blueMove = UIImageView()
    var existingTransition : CGAffineTransform?
    var clock = Int()
    var currentView: UIView?
    var g2 = UIPanGestureRecognizer()
    var g3 = UIPanGestureRecognizer()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        greenMove.isUserInteractionEnabled = true
        blueMove.isUserInteractionEnabled = true

        g2 = UIPanGestureRecognizer(target: self, action: #selector(ViewController.g1Method))
        greenMove.addGestureRecognizer(g2)
        g3 = UIPanGestureRecognizer(target: self, action: #selector(ViewController.g2Method))
        blueMove.addGestureRecognizer(g3)

        greenMove.backgroundColor = .systemGreen

        blueMove.backgroundColor = .blue


        [greenMove,slider,blueMove].forEach {

            view.addSubview($0)
            $0.translatesAutoresizingMaskIntoConstraints = false

        }


        //image11
        image1Width =  greenMove.widthAnchor.constraint(equalTo:  view.widthAnchor ,multiplier:  0.2)
        image1Height =  greenMove.heightAnchor.constraint(equalTo:  view.heightAnchor ,multiplier:  0.20)

        //image12
        image1Width2 =  blueMove.widthAnchor.constraint(equalTo:  view.widthAnchor ,multiplier:  0.2)
        image1Height2 =  blueMove.heightAnchor.constraint(equalTo:  view.heightAnchor ,multiplier:  0.20)



        NSLayoutConstraint.activate([

            greenMove.topAnchor.constraint(equalTo: view.topAnchor, constant : 0),
            image1Width,
            image1Height,
            greenMove.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant :0),


            blueMove.topAnchor.constraint(equalTo: view.topAnchor, constant : 0),
            image1Width2,
            image1Height2,
            blueMove.leadingAnchor.constraint(equalTo: greenMove.trailingAnchor, constant :0)

        ])








        slider.addTarget(self, action: #selector(hhh), for: .allEvents)

    }

    override func viewDidLayoutSubviews() {
        NSLayoutConstraint.activate ([




            slider.topAnchor.constraint(equalTo: view.topAnchor, constant : greenMove.bounds.height),
            slider.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.20, constant: 0),
            slider.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.20, constant: 0),
            slider.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant : 0),


        ])
    }
    @objc func handleTapGestured(_ gesture: UIPanGestureRecognizer) {
        currentView = gesture.view
    }

    @objc func g1Method(_ sender: UIPanGestureRecognizer){
        clock = 1
        let subview = greenMove
        guard let child = sender.view else{return}
        let transitionPoint = sender.translation(in: self.view)
        let newTransition = CGAffineTransform(translationX: transitionPoint.x, y: transitionPoint.y)
        switch sender.state {

        case .ended,.cancelled:// on End
            if let existing = existingTransition{
                self.existingTransition = newTransition.concatenating(existing)
            }else{
                self.existingTransition = newTransition
            }
        default://on change and other states
            if let existing = existingTransition{
                child.transform = newTransition
                    .concatenating(existing)
            }else{
                child.transform = newTransition
            }
        }
        self.view.layoutIfNeeded()


        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTapGestured(_:)))
        subview.addGestureRecognizer(tapGesture)


    }
    @objc func g2Method(_ sender: UIPanGestureRecognizer){
        clock = 2
        let subview = blueMove
        guard let child = sender.view else{return}
        let transitionPoint = sender.translation(in: self.view)
        let newTransition = CGAffineTransform(translationX: transitionPoint.x, y: transitionPoint.y)
        switch sender.state {

        case .ended,.cancelled:// on End
            if let existing = existingTransition{
                self.existingTransition = newTransition.concatenating(existing)
            }else{
                self.existingTransition = newTransition
            }
        default://on change and other states
            if let existing = existingTransition{
                child.transform = newTransition
                    .concatenating(existing)
            }else{
                child.transform = newTransition
            }
        }
        self.view.layoutIfNeeded()


        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTapGestured(_:)))
        subview.addGestureRecognizer(tapGesture)


    }
    @objc func hhh() {

        if clock ==  1 {
            image1Width.constant = CGFloat(slider.value) * view.frame.size.width * 0.25
            image1Height.constant = CGFloat(slider.value) * view.frame.size.height * 0.25
        }
        if clock  == 2 {

            image1Width2.constant = CGFloat(slider.value) * view.frame.size.width * 0.25
            image1Height2.constant = CGFloat(slider.value) * view.frame.size.height * 0.25
        }




    }

}

Answer 1

[最好的方法是在安全区域前导和图像前导之间为blu图像创建前导约束，而不是在两个图像之间创建前导约束，因为当禁用两个图像之间的约束时，会出现错误，因为视图不知道在哪里放图片