I'm trying to create a custom one-button AlertViewController in Swift, I use window.addSubview() to show the AlertView, but when touch the button on the AlertView, the func buttonTapped() is not working, below is my code, please tell me what's wrong here, thanks.
MyAlertViewController.swift
class MyAlertViewController: UIViewController {
var button: UIButton!
var contentView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
setUp()
}
func setUp(){
contentView = UIView(frame: CGRectMake(0,0,200,300))
contentView.center = view.center
contentView.backgroundColor = UIColor.whiteColor()
contentView.layer.cornerRadius = 10
button = UIButton(type: .System)
button.frame = CGRectMake(50, 150, 100, 40)
button.setTitle("button", forState: UIControlState.Normal)
button.addTarget(self, action: #selector(buttonTapped(_:)), forControlEvents: UIControlEvents.TouchUpInside)
view.addSubview(contentView)
contentView.addSubview(button)
view.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.1)
view.userInteractionEnabled = true
}
func buttonTapped(sender: AnyObject?){
print("button tapped")
}
func show(){
let window = UIApplication.sharedApplication().keyWindow! as UIWindow
view.frame = window.bounds
window.addSubview(view)
}
}
class ParentViewController: UIViewController {
var button: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.whiteColor()
button = UIButton(type: .System)
button.frame = CGRectMake(110,269,100,30)
button.setTitle("show", forState: .Normal)
button.addTarget(self, action: #selector(buttonTapped(_:)), forControlEvents: .TouchUpInside)
view.addSubview(button)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func buttonTapped(sender: AnyObject?){
MyAlertViewController().show()
}
}
class ParentViewController: UIViewController {
var button: UIButton!
var vc: MyAlertViewController!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.cyanColor()
button = UIButton(type: .System)
button.frame = CGRectMake(110,269,100,30)
button.setTitle("show", forState: .Normal)
button.addTarget(self, action: #selector(buttonTapped(_:)), forControlEvents: .TouchUpInside)
view.addSubview(button)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func buttonTapped(sender: AnyObject?){
vc = MyAlertViewController()
vc.show()
}
}
TLDR,
You have to retain an instance of MyAlertViewController().
Change to this and it will work (as you've already done):
// keep some reference
var alert: MyAlertViewController?
func buttonTapped(sender: AnyObject?){
alert = MyAlertViewController()
alert?.show()
}
More explanation,
the button.addTarget(self, ...)
that is called inside MyAlertViewController does not retain self
.
The last line of the doc of addTarget
function said that:
// ... the action cannot be NULL. Note that the target is not retained.*
So there will be no self
to send action to after leaving of this function:
func buttonTapped(sender: AnyObject?){
MyAlertViewController().show()
}
Another option,
is to keep self
variable in MyAlertViewController:
// retain self manually
var mySelf: MyAlertViewController?
func setUp(){
...
// reference to self
mySelf = self
button.addTarget(mySelf, action: #selector(buttonTapped(_:)), forControlEvents: UIControlEvents.TouchUpInside)
}