Warning - Attempt to present UIAlertController null in Swift - ios

Question

I have an UIAlertController running in my project which is connected through UIButton.My code works ok.But,Everytime when I pressed the button Xcode console printing an alert as below and I went through all the similar question been asked in stackOverflow but no answer.Attempt to present UIAlertController on UIViewController whose view is not in the window hierarchy
2016-10-03 19:14:35.854 xxxxxx[85186:7214348] Warning: Attempt to present<UIAlertController: 0x7f8d99450820> on <yyyyyyy.ViewController: 0x7f8d9a025200> which is already presenting (null)
My Code Below:
override func viewDidLoad() {
super.viewDidLoad()
self.moreButton.frame = CGRect(x:view.frame.width / 2, y: view.frame.height / 2, width: 100, height: 40)
moreButton.center = view.center
moreButton.backgroundColor = UIColor.darkText.withAlphaComponent(0.4)
moreButton.layer.masksToBounds = true
moreButton.setTitle("More", for: UIControlState())
moreButton.setTitleColor(UIColor.white, for: UIControlState())
moreButton.showsTouchWhenHighlighted = true
moreButton.layer.cornerRadius = 5.0
moreButton.addTarget(self, action: #selector(ViewController.moreButtonAction(_:)), for: .allTouchEvents)
self.view.addSubview(self.moreButton)
}
func moreButtonAction(_ sender: UIButton) {
DispatchQueue.main.async(execute: {
let myAlert = UIAlertController(title: nil, message: nil, preferredStyle: UIAlertControllerStyle.actionSheet)
myAlert.view.tintColor = UIColor.purple.withAlphaComponent(0.8)
let myAction_1 = UIAlertAction(title: " Title 1", style: UIAlertActionStyle.default, handler: {
(action: UIAlertAction!) in
})
let myAction_2 = UIAlertAction(title: " Title 2", style: UIAlertActionStyle.default, handler: {
(action: UIAlertAction!) in
})
let myAction_3 = UIAlertAction(title: " Title 3", style: UIAlertActionStyle.default, handler: {
(action: UIAlertAction!) in
})
let myAction_4 = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: {
(action: UIAlertAction!) in
})
myAlert.addAction(myAction_1)
myAlert.addAction(myAction_2)
myAlert.addAction(myAction_3)
myAlert.addAction(myAction_4)
self.present(myAlert, animated: true, completion: nil)
})
}
Thanks in Advance

Answer 1

The error is telling you that you are trying to present an alertController that is already active. You could check if your controller has an active alert otherwise show it. This will remove the warning. So basically move your self.present row with the following:
if !(self.navigationController?.visibleViewController?.isKind(of: UIAlertController.self))! {
self.present(myAlert, animated: true, completion: nil)
}
Replace your moreActionButton function with the following:
func moreButtonAction(_ sender: UIButton) {
let myAlert = UIAlertController(title: nil, message: nil, preferredStyle: UIAlertControllerStyle.actionSheet)
myAlert.view.tintColor = UIColor.purple.withAlphaComponent(0.8)
let myAction_1 = UIAlertAction(title: " Title 1", style: UIAlertActionStyle.default, handler: {
(action: UIAlertAction!) in
})
let myAction_2 = UIAlertAction(title: " Title 2", style: UIAlertActionStyle.default, handler: {
(action: UIAlertAction!) in
})
let myAction_3 = UIAlertAction(title: " Title 3", style: UIAlertActionStyle.default, handler: {
(action: UIAlertAction!) in
print("3")
})
let myAction_4 = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: {
(action: UIAlertAction!) in
})
myAlert.addAction(myAction_1)
myAlert.addAction(myAction_2)
myAlert.addAction(myAction_3)
myAlert.addAction(myAction_4)
if !(self.navigationController?.visibleViewController?.isKind(of: UIAlertController.self))! {
self.present(myAlert, animated: true, completion: nil)
}
}