ios - swift 地，我如何以编程方式制作 View 层？

Question

在 Swift 中，我有一个包含三个对象的 View 。我希望按钮和标签位于图像之上。这是一个类似于 Photoshop 中的图层的概念。目前，图像位于按钮和标签之上，因此您看不到按钮和标签。这是怎么做到的？

我的代码在这里:

import UIKit

    class ViewController: UIViewController {
        override func viewDidLoad() {
            super.viewDidLoad()
            // Do any additional setup after loading the view, typically from a nib.
            let myFirstLabel = UILabel()
            let myFirstButton = UIButton()
            let myFirstImage = UIImage(named: "1792614.jpg")
            let myFirstImageView = UIImageView(image: myFirstImage)

            myFirstLabel.text = "I made a label on the screen #toogood4you"
            myFirstLabel.font = UIFont(name: "MarkerFelt-Thin", size: 45)
            myFirstLabel.textColor = UIColor.redColor()
            myFirstLabel.textAlignment = .Center
            myFirstLabel.numberOfLines = 5
            myFirstLabel.frame = CGRectMake(15, 54, 300, 500)

            myFirstButton.setTitle("✸", forState: .Normal)
            myFirstButton.setTitleColor(UIColor.blueColor(), forState: .Normal)
            myFirstButton.frame = CGRectMake(160, 284, 50, 50)
            myFirstButton.addTarget(self, action: "pressed:", forControlEvents: .TouchUpInside)

            self.view.addSubview(myFirstLabel)
            self.view.addSubview(myFirstButton)
            self.view.addSubview(myFirstImageView)
        }

        func pressed(sender: UIButton!) {
            var alertView = UIAlertView()
            alertView.addButtonWithTitle("Ok")
            alertView.title = "title"
            alertView.message = "message"
            alertView.show()
        }

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


    }

Answer 1

答案在这里:

self.view.addSubview(myFirstLabel)
self.view.addSubview(myFirstButton)
self.view.addSubview(myFirstImageView)

当你添加一个 subview 时，它总是被放在顶部，为了达到你想要的效果，先在底部添加你想要的 View ，最后在顶部添加你想要的 View :

self.view.addSubview(myFirstImageView)
self.view.addSubview(myFirstButton)
self.view.addSubview(myFirstLabel)