以下两行解决了我的问题
view.heightAnchor.constraintEqualToConstant(50).active = true;
view.widthAnchor.constraintEqualToConstant(350).active = true;
迅捷版-
var DynamicView=UIView(frame: CGRectMake(100, 200, 100, 100))
DynamicView.backgroundColor=UIColor.greenColor()
DynamicView.layer.cornerRadius=25
DynamicView.layer.borderWidth=2
self.view.addSubview(DynamicView)
DynamicView.heightAnchor.constraintEqualToConstant(50).active = true;
DynamicView.widthAnchor.constraintEqualToConstant(350).active = true;
var DynamicView2=UIView(frame: CGRectMake(100, 310, 100, 100))
DynamicView2.backgroundColor=UIColor.greenColor()
DynamicView2.layer.cornerRadius=25
DynamicView2.layer.borderWidth=2
self.view.addSubview(DynamicView2)
DynamicView2.heightAnchor.constraintEqualToConstant(50).active = true;
DynamicView2.widthAnchor.constraintEqualToConstant(350).active = true;
var DynamicView3:UIView=UIView(frame: CGRectMake(10, 420, 355, 100))
DynamicView3.backgroundColor=UIColor.greenColor()
DynamicView3.layer.cornerRadius=25
DynamicView3.layer.borderWidth=2
self.view.addSubview(DynamicView3)
let yourLabel:UILabel = UILabel(frame: CGRectMake(110, 10, 200, 20))
yourLabel.textColor = UIColor.whiteColor()
//yourLabel.backgroundColor = UIColor.blackColor()
yourLabel.text = "mylabel text"
DynamicView3.addSubview(yourLabel)
DynamicView3.heightAnchor.constraintEqualToConstant(50).active = true;
DynamicView3.widthAnchor.constraintEqualToConstant(350).active = true;
let stackView = UIStackView()
stackView.axis = UILayoutConstraintAxis.Vertical
stackView.distribution = UIStackViewDistribution.EqualSpacing
stackView.alignment = UIStackViewAlignment.Center
stackView.spacing = 30
stackView.addArrangedSubview(DynamicView)
stackView.addArrangedSubview(DynamicView2)
stackView.addArrangedSubview(DynamicView3)
stackView.translatesAutoresizingMaskIntoConstraints = false;
self.view.addSubview(stackView)
//Constraints
stackView.centerXAnchor.constraintEqualToAnchor(self.view.centerXAnchor).active = true
stackView.centerYAnchor.constraintEqualToAnchor(self.view.centerYAnchor).active = true