UIButton无法在子ViewController中加载

Question

I've got a MainViewController where I'm loading a slideout-menu. The MainViewController contains a static TopView and a ContentView where different child controllers or views are loaded, depending on which menu entry was selected.

There is a button inside one of the children is loaded, but it is not working. When I start the app with the ViewController including the button, set to "is initial View Controller", everything works properly.

When starting the app with the MainViewController as initial View Controller with a loaded child, the button is not working (it is loaded in the view, but not reacting). Any suggestions how I can make this work?

MainViewController loading of Child View

class MainViewController: UIViewController, SideBarDelegate {
var contentView = UIView()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    ....
    contentView.backgroundColor = UIColor(red: 70/255, green: 174/255, blue: 253/255, alpha: 1)
    contentView.translatesAutoresizingMaskIntoConstraints = false
    self.view.addSubview(contentView)
    contentView.topAnchor.constraint(equalTo: statusBarView.bottomAnchor).isActive = true
    contentView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
    contentView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
    contentView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
    contentView.layoutIfNeeded()

}

func sideBarDidSelectButtonAtIndex(_ index: Int) {
    ...       
    if index == 0{
        statusBarLabel.text = "First"
        let controller:FirstViewController = storyboard!.instantiateViewController(withIdentifier: "First") as! FirstViewController
        controller.view.frame = ContentView.bounds
        controller.willMove(toParentViewController: self)
        contentView.addSubview(controller.view)
        controller.didMove(toParentViewController: self)
        print("touched index 0")
    } else if index == 1{
        // index is 1
    }
}

FirstViewController

class FirstViewController: UIViewController, UIScrollViewDelegate {

    let addButton = UIButton()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.backgroundColor = UIColor(red: 230/255, green: 230/255, blue: 230/255, alpha: 1)

        addButton.frame = CGRect(x: 0, y: 0, width: self.view.frame.size.width, height: 60)
        addButton.clipsToBounds = true
        addButton.setTitleColor(UIColor.white, for: .normal)
        addButton.backgroundColor = UIColor(red: 102/255, green: 204/255, blue: 255/255, alpha: 1)
        addButton.setTitle("add feed", for: .normal)
        addButton.titleLabel?.font = UIFont.systemFont(ofSize: 20, weight: UIFontWeightRegular)
        self.view.addSubview(AddButton)
        addButton.layoutIfNeeded()
        addButton.addTarget(self, action: #selector(touchUpAddButton), for: UIControlEvents.touchUpInside)
        addButton.addTarget(self, action: #selector(touchDownAddButton), for: UIControlEvents.touchDown)

    func touchUpAddButton() {
        addButton.backgroundColor = UIColor(red: 102/255, green: 204/255, blue: 255/255, alpha: 1)
    }

    func touchDownAddButton() {
        addButton.backgroundColor = UIColor(red: 70/255, green: 174/255, blue: 253/255, alpha: 1)
    }
}

Answer 1

Update your functions to these

func TouchUpAddButton(sender: UIButton){
    addButton.backgroundColor = UIColor(red: 102/255, green: 204/255, blue: 255/255, alpha: 1)

}

func TouchDownAddButton(sender: UIButton) {
    addButton.backgroundColor = UIColor(red: 70/255, green: 174/255, blue: 253/255, alpha: 1)
}

And change your code of adding the target to

addButton.addTarget(self, action: #selector(FirstViewController.touchUpAddButton(_:)), for: .touchDown)
addButton.addTarget(self, action: #selector(FirstViewController.touchDownAddButton(_:)), for: .touchDown)

Answer 2

While adding the view in the container you don't have to use addSubview function, that the FirstViewController functionality is not working.

Use below code:

let newViewController:FirstViewController = storyboard!.instantiateViewController(withIdentifier: "First") as! FirstViewController
let oldViewController  = childViewControllers.last! as UIViewController
    oldViewController.willMove(toParentViewController: nil)
    addChildViewController(newViewController)
    transition(from: oldViewController, to: newViewController, duration: 0.25, options: .transitionCrossDissolve, animations:{ () -> Void in
        // nothing needed here
    }, completion: { (finished) -> Void in
        oldViewController.removeFromParentViewController()
        newViewController.didMove(toParentViewController: self)
    })

You can change the duration, it used for animation

Answer 3

First solution:

Remove an autolayout constrains

Second solution:

Button is not performing an action because a child view controller view should be added directly to a container controller view (in your case: MainViewController view) and not via an intermediate view (in your case: contentView )