连接到平移手势的 y 轴上的中心对象 编辑：

如何解决连接到平移手势的 y 轴上的中心对象 编辑：

我希望我的 swift 代码将连接到 uipangesture 的框架居中到 y 轴。您可以在我在下面创建的 gif 中看到我正在寻找的内容。现在我已经想出了一种方法来做到这一点。我发现你可以使用 nslayout 约束来做类似的事情，并将它们设置为 true。但是它将框移动到屏幕顶部，我想做一些类似于下面的 gif 的事情。

import UIKit

class ViewController: UIViewController {
    
    var container = UIView()
  
    
    var panGesture = UIPanGestureRecognizer()
    var btn = UIButton()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        
        [container,btn].forEach{
            $0.translatesAutoresizingMaskIntoConstraints = false
            view.addSubview($0)
        }
        container.isUserInteractionEnabled = true
        btn.frame = CGRect(x: 100,y: 300,width: 100,height: 100)
        container.frame = CGRect(x: 100,y: 100,height: 100)
        container.backgroundColor = .blue
        btn.backgroundColor = .red
        panGesture = UIPanGestureRecognizer(target: self,action: #selector(ViewController.draggedView(_:)))
        container.isUserInteractionEnabled = true
        container.addGestureRecognizer(panGesture)
        
        btn.addTarget(self,action: #selector(centerYAlighment),for: .touchDown)

    }
    
    @objc func draggedView(_ sender: UIPanGestureRecognizer) {
        self.view.bringSubview(toFront: container)
        let translation = sender.translation(in: self.view)
        container.center = CGPoint(x: container.center.x + translation.x,y: container.center.y + translation.y)
        sender.setTranslation(CGPoint.zero,in: self.view)
        
        
        
        
        
    }
    
    @objc func centerYAlighment(){
       
    }


}

解决方法

有关如何将蓝色方块的平移限制为仅沿 Y 轴中心，请参阅此答案的历史

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编辑：

如果您希望红色按钮使蓝色方块水平居中，只需在 container.center.x = view.center.x 内执行 centerYAlignment()。

class ViewController: UIViewController {
    
    var container = UIView()
      
    var panGesture = UIPanGestureRecognizer()
    var btn = UIButton()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        [container,btn].forEach{
            $0.translatesAutoresizingMaskIntoConstraints = false
            view.addSubview($0)
        }
        container.isUserInteractionEnabled = true
        btn.frame = CGRect(x: 100,y: 300,width: 100,height: 100)
        container.frame = CGRect(x: 100,y: 100,height: 100)
        container.backgroundColor = .blue
        btn.backgroundColor = .red
        panGesture = UIPanGestureRecognizer(target: self,action: #selector(draggedView(_:)))
        container.isUserInteractionEnabled = true
        container.addGestureRecognizer(panGesture)
        
        btn.addTarget(self,action: #selector(centerYAlignment),for: .touchDown)

    }
    
    @objc func draggedView(_ sender: UIPanGestureRecognizer) {
        self.view.bringSubviewToFront(container)
        let translation = sender.translation(in: self.view)
        container.center = CGPoint(x: container.center.x + translation.x,y: container.center.y + translation.y)
        sender.setTranslation(CGPoint.zero,in: self.view)
    }
    
    
    @objc func centerYAlignment() {
        container.center.x = view.center.x /// here!
    }
}

结果：