编程添加根视图以查看控制器不正确定位

Question

我试图添加根视图和子视图的视图控制器编程，但视图未完全填满筛选按预期：

override func loadView() { 
     self.view = UIView(frame: CGRect(x: 0.0, y: 0.0, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)) 
     self.view.backgroundColor = UIColor.blue 
    } 

    override func viewDidLoad() { 

     let alertView = Bundle.main.loadNibNamed("CHRApptTakenAlertView", owner: self, options: nil)![0] as! CHRApptTakenAlertView 

     self.view.translatesAutoresizingMaskIntoConstraints = false 
     alertView.translatesAutoresizingMaskIntoConstraints = false 

     self.view.addSubview(alertView) 
     self.view.addConstraint(NSLayoutConstraint(item: alertView, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerX, multiplier: 1, constant: 0)) 
     self.view.addConstraint(NSLayoutConstraint(item: alertView, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: self.view, attribute: NSLayoutAttribute.centerY, multiplier: 1, constant: 0)) 
     alertView.addConstraint(NSLayoutConstraint(item: alertView, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.width, multiplier: 1, constant: 350)) 
     alertView.addConstraint(NSLayoutConstraint(item: alertView, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.height, multiplier: 1, constant: 250)) 

     alertView.closeBtn.addTarget(self, action: #selector(self.closeBtnTouch), for: UIControlEvents.touchUpInside) 
    } 

Answer 1

取出线self.view.translatesAutoresizingMaskIntoConstraints = false，并在添加约束后调用self.view.layoutIfNeeded（）。