ios - addArrangedSubview并调整StackView的大小

我正在尝试使用按钮将视图添加到StackView中:

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var stackOutlet: UIStackView!
    @IBOutlet weak var buttonOutlet: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func buttonAction(_ sender: AnyObject) {
        let newView = UIView(frame: CGRect(x: 0, y: 0, width: 240, height: 128))
        newView.heightAnchor.constraint(equalToConstant: 128)
        newView.widthAnchor.constraint(equalToConstant: 240)
        newView.backgroundColor = UIColor.green

        stackOutlet.addArrangedSubview(newView)
        stackOutlet.heightAnchor.constraint(equalToConstant: stackOutlet.frame.size.height + 128)
        print(stackOutlet.subviews.count)
    }
}

子视图的数量正在增加，但是屏幕上没有任何变化。我怀疑我的StackView无法正确调整大小吗？

最佳答案

没关系，我找到了解决方案:

newView.widthAnchor.constraint(equalToConstant: 240).isActive = true
newView.heightAnchor.constraint(equalToConstant: 128).isActive = true

您需要.isActive = true