Question

我已将一个ImageView作为子视图添加到Swift中的集合视图中。此子视图的初始点使用viewDidLoad()中的锚点进行布局。但是，在视图中点击手势后重新调整键盘后，ImageView会返回到原始位置。我怎么能最好地解决这个问题？

import UIKit

class MessageViewController: UICollectionViewController,UICollectionViewDelegateFlowLayout {

     let imageButton: UIImageView = {
         let imageButtonView = UIImageView()
         imageButtonView.image = UIImage(named: "image.png")
         imageButtonView.layer.cornerRadius = 30
         imageButtonView.layer.masksToBounds = true
         imageButtonView.isUserInteractionEnabled = true
         return imageButtonView
     }()

     override func viewDidLoad() {
         super.viewDidLoad()

         //add imageButton
         view.addSubview(imageButton)

     //        recognize tapgesture for removing keyboard
         let tapGesture = UITapGestureRecognizer(target: self, action: #selector(self.tap(gesture:)))
         self.view.addGestureRecognizer(tapGesture)

         let panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.handlePan(gesture:)))
         imageButton.addGestureRecognizer(panGesture)
     }


    func handlePan(gesture: UIPanGestureRecognizer) {

        let translation = gesture.translation(in: self.view)
            if let view = gesture.view {
                view.center = CGPoint(x:view.center.x + translation.x, y:view.center.y + translation.y)
    }
    gesture.setTranslation(CGPoint.zero, in: self.view)
  }


    imageButton.translatesAutoresizingMaskIntoConstraints = false

    imageButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    imageButton.centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: 30).isActive = true
    imageButton.heightAnchor.constraint(equalToConstant: 60).isActive = true
    imageButton.widthAnchor.constraint(equalToConstant: 60).isActive = true

 }

Answer 1

我假设键盘被解除后，调用view.setNeedsLayout()，将约束重置为原始位置。

仅使用约束来尝试此操作，而不是调整边界（或中心）

let imageCenterXConstraint:NSLayoutConstraint = NSLayoutConstraint()
let imageCenterYConstraint:NSLayoutConstraint = NSLayoutConstraint()

func viewDidLoad() {
    super.viewDidLoad()

    //add imageButton
    view.addSubview(imageButton)

    //        recognize tapgesture for removing keyboard
    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(self.tap(gesture:)))
    self.view.addGestureRecognizer(tapGesture)

    let panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.handlePan(gesture:)))
    imageButton.addGestureRecognizer(panGesture)
    imageButton.translatesAutoresizingMaskIntoConstraints = false

    imageCenterXConstraint = imageButton.centerXAnchor.constraint(equalTo: view.centerXAnchor)
    imageCenterXConstraint.isActive = true
    imageCenterYConstraint = imageButton.centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: 30)
    imageCenterYConstraint.isActive = true
    imageButton.heightAnchor.constraint(equalToConstant: 60).isActive = true
    imageButton.widthAnchor.constraint(equalToConstant: 60).isActive = true
}

func handlePan(gesture: UIPanGestureRecognizer) {
    let translation = gesture.translation(in: self.view)
    if let view = gesture.view {
        imageCenterXConstraint.constant = translation.x
        imageCenterYConstraint.constant = 30 + translation.y
        view.layoutIfNeeded()
    }
    gesture.setTranslation(CGPoint.zero, in: self.view)
}

在辞职键盘后如何保持子视图，用平移手势移动到位？

1 个答案: