作为子视图添加到背景图像后，按钮不起作用

Question

我有一个有效的登录Viewcontroller，但是当我添加背景图像时，按钮的功能不起作用，没有语法错误。当我仅将其添加为背景图像时，每个按钮都可以正常工作，但是当我将按钮添加为子视图时，则按钮不起作用。

这是我的VC：

import UIKit
import CoreData
import Foundation

@available(iOS 11.0, *)
class ViewController: UIViewController {

    var imageView = UIImageView()

    @IBOutlet weak var signupButton: UIButton!
    @IBOutlet weak var directButton: UIButton!

    @IBOutlet weak var emailText: UITextField!
    @IBOutlet weak var passText: UITextField!

    @IBOutlet weak var loginButton: UIButton!
    @IBAction func loginAction(_ sender: Any) {

            let appDel = UIApplication.shared.delegate as! AppDelegate
            let context = appDel.persistentContainer.viewContext
            var isMatched = false
            let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
            request.returnsObjectsAsFaults = false
            do {
                let results = try! context.fetch(request)
                if(results.count > 0){
                    for result in results as! [NSManagedObject]
                    {
                        if  emailText.text == result.value(forKey: "username") as? String && passText.text == result.value(forKey: "password") as? String {
                            print(emailText.text!, passText.text!)
                           // usernameGlobal = self.emailText.text!
                            let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle : nil)
                            let desController = mainStoryBoard.instantiateViewController(withIdentifier: "AddViewController") as! AddViewController
                            let newFrontViewController = UINavigationController.init(rootViewController:desController)
                            revealViewController().pushFrontViewController(newFrontViewController, animated: true)
                            isMatched = true
                            break
                        }
                    }

                    if !isMatched {
                        let alertController = UIAlertController(title: "Oops!", message: "Incorrect username or password", preferredStyle: .alert)
                        let defaultAction = UIAlertAction(title: "OK", style: .default, handler: nil)
                        alertController.addAction(defaultAction)
                        present(alertController, animated: true, completion: nil)
                    }
                }
            }
    }



    @IBAction func directAction(_ sender: Any) {


        let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle : nil)
        let desController = mainStoryBoard.instantiateViewController(withIdentifier: "AddViewController") as! AddViewController
        let newFrontViewController = UINavigationController.init(rootViewController:desController)
        revealViewController().pushFrontViewController(newFrontViewController, animated: true)


    }



    @IBAction func signupSegue(_ sender: Any) {

        let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle : nil)
        let desController = mainStoryBoard.instantiateViewController(withIdentifier: "SignupViewController") as! SignupViewController
        let newFrontViewController = UINavigationController.init(rootViewController:desController)
        revealViewController().pushFrontViewController(newFrontViewController, animated: true)
    }


    override func viewDidLoad() {
        super.viewDidLoad()

        imageView = UIImageView(frame: UIScreen.main.bounds)
        imageView.image = #imageLiteral(resourceName: "dsplash")
        imageView.contentMode = .scaleAspectFill
         imageView.alpha = 0.5

        self.view.addSubview(imageView)

        self.imageView.addSubview(emailText)
        self.imageView.addSubview(passText)
        self.imageView.addSubview(loginButton)
        self.imageView.addSubview(signupButton)
        self.imageView.addSubview(directButton)

        loginButton.backgroundColor = UIColor.blue
    }

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

Answer 1

不要将按钮添加为的子视图imageView，它们由情节提要布局。而是只需更改以下代码行：

self.view.addSubview(imageView)

对此：

self.view.insertSubview(imageView, at: 0)

然后删除放置按钮作为的子视图的代码行imageView。

这会将图像放置在按钮下方，因此它将看起来像您想要的那样，并且按钮将继续工作。

甚至更好的是，imageView通过情节提要添加它（我喜欢保持一致）。要将其保留为背景图像，只需将imageViewint View Controller Scene 拖到子视图的顶部，以便它是该视图的第一个子视图-它将使视图的所有其余部分都显示在它的前面：

另外，如果您有充分的理由将按钮保留为imageView子视图，请进行设置imageView.userInteractionEnabled = true以使其与按钮一起用作的子视图imageView。