swift - 如何改变UIButton的位置？

Question

什么也没发生，但为什么？？？

@IBOutlet weak var button10: UIButton!

override func viewDidLoad() {
    super.viewDidLoad()

    button10.center = CGPoint(x: self.view.frame.x/2, y: self.view.frame.y/2)

 }

Answer 1

添加 View 中心约束

var constX = NSLayoutConstraint(item: button10, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0)
view.addConstraint(constX)

var constY = NSLayoutConstraint(item: button10, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0)
view.addConstraint(constY)