I want to show alertViewController on my rootViewController in AppDelegate when app is launched. Here snippet of code:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
let alert: UIAlertController = UIAlertController(title: "This is title", message: "This is message.", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default))
self.window?.rootViewController?.present(alert, animated: true, completion: nil)
return true
}
alert is not appearing on rootViewController. Please help me.
The reason is that the view isn't yet loaded, if you look at console you may find log like this:
Warning: Attempt to present on 'swiftHere.ViewController: 0x7ff289007740' whose view is not in the window hierarchy!
You may dispatch it until rootViewController loads:
DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
let alert: UIAlertController = UIAlertController(title: "This is title", message: "This is message.", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default))
self.window?.rootViewController?.present(alert, animated: true, completion: nil)
}
Related
In context of this question/answer I've attempted but the result is no alert presented.
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
let alertController = UIAlertController(title: "Error", message: "ABc", preferredStyle: UIAlertController.Style.alert)
alertController.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
let win = UIWindow(frame: UIScreen.main.bounds)
let vc = UIViewController()
vc.view.backgroundColor = .clear
win.rootViewController = vc
win.windowLevel = UIWindow.Level.alert + 1 // Swift 3-4: UIWindowLevelAlert + 1
win.makeKeyAndVisible()
vc.present(alertController, animated: true, completion: nil)
return true
}
Attempt 2 based on the answer.
Use below line:
self.window?.rootViewController?.present(alertController, animated: true, completion: nil)
Instead of
vc.present(alertController, animated: true, completion: nil)
than problem is solved.
Example:
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.5, execute: {
let alertController = UIAlertController(title: "Alert Title", message:
"Message", preferredStyle: .actionSheet)
let okAction = UIAlertAction(title: "Ok", style:.default) {
UIAlertAction in
NSLog("OK Pressed")
}
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) {
UIAlertAction in
NSLog("Cancel Pressed")
}
alertController.addAction(okAction)
alertController.addAction(cancelAction)
self.window?.rootViewController?.present(alertController, animated: true, completion: nil)
})
So what i am trying to achieve is when a notification launch and the user tap on it, an Alert controller should appear with 2 options. However, when the app launch from the notification tap, nothing appears.
These codes are inside the AppDelegate.swift file
func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: #escaping () -> Void) {
showAlert()
}
func showAlert() {
let alert = UIAlertController(title: "Confirm", message: "Confirm?", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "No", style: .destructive, handler: nil))
alert.addAction(UIAlertAction(title: "Yes", style: .default, handler: nil))
window?.rootViewController?.present(alert, animated: true, completion: nil)
}
var topVC: UIWindow? = UIWindow(frame: UIScreen.main.bounds)
topVC?.rootViewController = UIViewController()
let alert = UIAlertController(title: "Alert", message: "Notification Received", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .cancel) { _ in
// action OK
})
topVC?.makeKeyAndVisible()
topVC?.rootViewController?.present(alert, animated: true, completion: nil)
Try this:
func showAlert() {
var alertController = UIAlertController(title: "Confirm", message: "Confirm?", preferredStyle: UIAlertControllerStyle.alert)
var okAction = UIAlertAction(title: "Yes", style: UIAlertActionStyle.Default) {
UIAlertAction in
// action
}
var cancelAction = UIAlertAction(title: "No", style: UIAlertActionStyle.Cancel) {
UIAlertAction in
// action
}
alertController.addAction(okAction)
alertController.addAction(cancelAction)
self.window?.rootViewController?.presentViewController(alertController, animated: true, completion: nil)
}
I think you are calling the func showAlert() from the wrong place.
When the app launch from the notification tap, the app gets an event in
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool
So you should try this,
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
//Handle remote notification event on app launch
if let remoteNotification = launchOptions?[UIApplication.LaunchOptionsKey.remoteNotification] {
showAlert()
}
}
I try to show an alert when the app launches (a tabbed app)
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
let welcomeAlert = UIAlertController(title: "Turn on Bluetooth?", message: "Turn on Bluetooth?", preferredStyle: UIAlertControllerStyle.alert)
welcomeAlert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: {
action in self.alertServerClient()
}))
welcomeAlert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: nil))
let alertWindow = UIWindow(frame: UIScreen.main.bounds)
alertWindow.rootViewController = UIViewController()
alertWindow.windowLevel = UIWindowLevelAlert + 1;
alertWindow.makeKeyAndVisible()
alertWindow.rootViewController?.present(welcomeAlert, animated: true, completion: nil)
return true
}
In alertServerClient() I want to change UIImage like
func alertServerClient() {
let vc = FirstViewController()
let imgBTOn = UIImage(named: "BT_Button.png")
vc.btnBT.setImage(imgBTOn, for: .normal)
}
Unfortunately, it doesn't work and throw error
Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value
Is it possible to change UI content from AppDelegate?
I am getting the following error:
Attempt to present on Check5GHz: whose view is not
in the window hierarchy!
SplashViewController:
let check5ghz = Check5GHz()
check5ghz.determineIf5GHz()
Here is what Check5GHz looks like:
class Check5GHz: UIViewController {
func determineIf5GHz()-> Void{
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
So it seems like the problem is that one ViewController is trying to launch an UIAlertController found in another ViewController which it does not seem to allow. But I need to have this UIAlertController appear from many different ViewControllers. Could you recommend another way?
extension UIViewController {
func determineIf5GHz()-> Void{
let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Click", style:
UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
}
Then in any of your view controllers do this:
self.determmineIf4GHz()
everyone!
When my app in foreground I want it to show alert when DidReceiveLocalNotification triggered.
I can add alert to mimic local notifications in AppDelegate.swift, but the problem is I don't know how to add method from my ViewController to UIAlertAction closure (see commented line), to finish animation when timer stopped.
My code below:
func application(application: UIApplication, didReceiveLocalNotification notification: UILocalNotification) {
let alertTimerEnds = UIAlertController(title: "Timer finished!", message: nil, preferredStyle: .Alert)
let okAction = UIAlertAction(title: "OK", style: .Default) { finished in
print("You've pressed OK button")
//self.ViewController().finishAnimation()
}
alertTimerEnds.addAction(okAction)
self.window?.rootViewController?.presentViewController(alertTimerEnds, animated: true, completion: nil)
}
Maybe I should do it in ViewController usind AppDelegate?
let someAppDelegate = UIApplication.sharedApplication().delegate as? AppDelegate
someAppDelegate?.application(UIApplication.sharedApplication(), didReceiveLocalNotification: UILocalNotification) { code for alert }
If you want to do that
func application(application: UIApplication, didReceiveLocalNotification notification: UILocalNotification)
{
var viewController : UIViewController = (application.keyWindow?.rootViewController)!
while ((viewController.presentedViewController) != nil) {
viewController = viewController.presentedViewController!
}
let alert = UIAlertController(title: "", message: notification.alertBody, preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: {(action: UIAlertAction!) in}))
viewController.presentViewController(alert, animated: true, completion: nil)
})
Show UIAlertController in didReceiveLocalNotification method
Try with below code, this will display alert on viewcontroller which is present at a moment.
func application(application: UIApplication, didReceiveLocalNotification notification: UILocalNotification) {
var latestViewController : UIViewController!
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
if let viewControllers = appDelegate.window?.rootViewController?.presentedViewController {
latestViewController = viewControllers as UIViewController
}
else if let viewControllers = appDelegate.window?.rootViewController?.childViewControllers {
latestViewController = viewControllers.last! as UIViewController
}
//var alert: UIAlertView!
//alert = UIAlertView(title: "Title", message:"Message , delegate: nil, cancelButtonTitle:"Ok" )
//alert.show()
let alert = UIAlertController(title: "Title", message:"Message", preferredStyle: .Alert)
let action = UIAlertAction(title: "OK", style: .Default) { _ in
// Put here any code that you would like to execute when
// the user taps that OK button (may be empty in your case if that's just
// an informative alert)
}
alert.addAction(action)
latestViewController.presentViewController(alert, animated: true){}
}
How do I migrate from UIAlertView (deprecated in iOS8)