In my app I display tow alert views. The second alert view should pop up if the first has been closed. Now I check if an alert view is displayed like this:
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let viewController = appDelegate.window!.rootViewController as! ViewController
if viewController.view.window != nil {
}
else {
let alertView = UIAlertController(title: NSLocalizedString("IAP", comment: "comment"), message: NSLocalizedString("IAP1", comment: "comment"), preferredStyle: .Alert)
alertView.addAction(UIAlertAction(title: "Ok", style: .Cancel, handler: nil))
viewController.presentViewController(alertView, animated: true, completion: nil)
}
I send the 2nd alert view if the first isn't displayed anymore. But if the first view is still displayed the 2nd alert view doesn't pops up anymore. So my question is if there's a waiting line for alert views and how can I solve this problem?
You should define a handler for the first action and present the 2nd alertView within the handler.
So instead of
UIAlertAction(title: "Ok", style: .Cancel, handler: nil)
you should do
UIAlertAction(title: "Ok", style: .Cancel) { (action) -> Void in
// Present the other alertView
}
If you are using a navigation controller, the general way to see if an alert is already displayed is to check the presentedViewController property.
if let _ = navigationController.presentedViewController {
print("is already presenting \(navigationController.presentedViewController)")
} else {
navigationController.presentViewController(alert, animated:true, completion:nil)
}
For a fast patch in any UIViewController : (Xcode 8.3.1 & Swift 3.1)
func blabla() {
if presentedViewController != nil {
delay(0.5, closure: {
self.blabla()
})
return
}
// other alert code here
}
Simple way to check in Swift
var isAlertViewPresenting: Bool {
get {
if self.presentedViewController is UIAlertController {
return true
}
return false
}
}
Related
I have a screen with a collection view, and a plus sign bar button item. When the plus sign is pressed, an alert window pops up, where the user can add information to the list. Upon hitting OK, I am trying to refresh the collection view, but I'm doing something wrong.
The print statement "passed guard" is achieved, and I can get the information they entered. Just can't refresh the view to reflect this without leaving and coming back. Any guidance? I've run into this a few times actually, so I'm clearly missing something. Thanks very much in advance.
#objc func newButtonPressed() {
let alert = UIAlertController(title: "Add", message: "", preferredStyle: .alert)
alert.addTextField { (textField) in
textField.placeholder = "Name"
}
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action) in
var name = ""
guard let textFields = alert.textFields else { return }
guard let navController = self.parent as? UINavigationController else { return }
guard let settingsVC = navController.topViewController as? SettingsVC else { return }
print("passed guard") // success
DispatchQueue.main.async {
settingsVC.collectionView.reloadData()
settingsVC.view.backgroundColor = .red
// For testing purposes, explicitly using main thread and setting to red
}
}))
alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
present(alert, animated: true, completion: nil)
}
May be you need to alter the collection dataSource
guard let textFields = alert.textFields else { return }
settingsVC.arr.append(textFields.first!.text!) // arr is collection dataSource
settingsVC.collectionView.reloadData()
I have one scenario when the user did not use the application for more than 5 min app will show a popup with session expiration message.
The code for session expiration is added in the appDelegate and from there the popup will be presented on the current view controller.
code is
#objc func applicationDidTimeout(notification: NSNotification) {
if (window?.rootViewController?.isKind(of: UITabBarController.self))! {
for view in window?.rootViewController?.view.subviews ?? [(window?.rootViewController?.view)!] {
if view.isKind(of: MBProgressHUD.self) {
return
}
}
if window?.rootViewController?.presentedViewController != nil {
window?.rootViewController?.dismiss(animated: true, completion: {
self.showMessage(message: Message.sessionTimeout)
})
} else {
self.showMessage(message: Message.sessionTimeout)
}
}
}
fileprivate func showMessage(message: String) {
let alert = UIAlertController(title: appName, message: message, preferredStyle: .alert)
let actionOkay = UIAlertAction(title: "OK", style: .default) { (action) in
DispatchQueue.main.async {
UIView.transition(with: self.window!, duration: 0.3, options: UIView.AnimationOptions.transitionCrossDissolve, animations: {
CommonFunctions.setLoginAsRootVC()
}, completion: nil)
}
}
alert.addAction(actionOkay)
self.window?.rootViewController?.present(alert, animated: true, completion: nil)
}
Now if the user is doing some data entry and at that time, if the user leaves application ideal for 5 min or more the keyboard will dismiss and the session expiration message shown there.
But as the text field's delegate method textFieldShouldEndEditing has some validation and if that validation fails it shows a popup with the message and ok button.
So when the user taps on the ok button in the session expiration message popup, it will redirect the user to the login screen but due to the text field's delegate method validation, it shows one pop up in the login screen.
Code for the validation fail message popup is
fileprivate func showErrorMessage(message: String) {
let alert = UIAlertController(title: appName, message: message, preferredStyle: .alert)
let actionOkay = UIAlertAction(title: "OK", style: .default) { (action) in
self.txtField.becomeFirstResponder()
}
alert.addAction(actionOkay)
self.present(alert, animated: true, completion: nil)
}
How to prevent the popup from being present in the login screen?
I try to get the proper way to prevent the popup from appearing on the login screen.
But Finally, I found one heck to solve this issue.
I have declared one boolean in AppDelegate and set it's value to false when I want to prevent the popup from appearing and then revert it back to true when I want to show the popup.
I know this is not the elegant or efficient solution for the issue, but it works for now.
If anyone knows the better answer can post here, I'm still open to any better solution.
#objc func applicationDidTimeout(notification: NSNotification)
{
let visibleView : UIViewController = self.getVisibleViewControllerFrom(self.window?.rootViewController)!
self.showMessage(message: Message.sessionTimeout,Controller: visibleView)
}
fileprivate func showMessage(message: String , Controller : UIViewController) {
let alert = UIAlertController(title: appName, message: message, preferredStyle: .alert)
let actionOkay = UIAlertAction(title: "OK", style: .default) { (action) in
//Now apply your code here to set login view controller as rootview
// This controller is for demo
window!.rootViewController = UIStoryboard(name: "Main", bundle:
nil).instantiateViewController(withIdentifier: "loginview")
window!.makeKeyAndVisible()
}
alert.addAction(actionOkay)
Controller.present(alert, animated: true, completion: nil)
}
//MARK:- Supporting method to get visible viewcontroller from window
func getVisibleViewControllerFrom(_ vc: UIViewController?) -> UIViewController? {
if let nc = vc as? UINavigationController {
return self.getVisibleViewControllerFrom(nc.visibleViewController)
} else if let tc = vc as? UITabBarController {
return self.getVisibleViewControllerFrom(tc.selectedViewController)
} else {
if let pvc = vc?.presentedViewController {
return self.getVisibleViewControllerFrom(pvc)
} else {
return vc
}
}
}
Try this code, I've use this code many times may be it's work for you.
This is my current code:
import UIKit
class classViewController: UIViewController {
// The function i want to call in other view controllers..
func alertView(title: String, message: String) {
var alert:UIAlertController = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: { (action) -> Void in
self.dismissViewControllerAnimated(true, completion: nil)
}))
self.presentViewController(alert, animated: true, completion: nil)
}
}
In the other view controller, where I've made an IBAction to perform this alertView, I have done this:
#IBAction func button(sender: AnyObject) {
classViewController().alertView("title", message: "message")
}
When I run the app, after tapping the button I get this error, but no alertView:
Warning: Attempt to present on
whose view is not in the
window hierarchy!
Right. If you want to make a global class that displays alerts, you need to pass in a reference to the current view controller, and use that instead of "self" in calls like presentViewController.
Your class should probably not be a subclass of UIViewController, since it looks like you're never displaying it to the screen.
I created a Utils class that is a subclass of NSObject.
It has a method showAlertOnVC that looks like this:
class func showAlertOnVC(targetVC: UIViewController?, var title: String, var message: String)
{
title = NSLocalizedString(title, comment: "")
message = NSLocalizedString(message, comment: "")
if let targetVC = targetVC
{
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
let okButton = UIAlertAction(
title:"OK",
style: UIAlertActionStyle.Default,
handler:
{
(alert: UIAlertAction!) in
})
alert.addAction(okButton)
targetVC.presentViewController(alert, animated: true, completion: nil)
}
else
{
println("attempting to display alert to nil view controller.")
println("Alert title = \(title)")
println("Alert message = \(message)")
}
}
Thank you for reading this. I would like to have a functions Swift file where I put all of the functions for my project into, that the other Swift files could call. I am trying to create an alert function in the functions file that, when I pass in a specific string, it shows a specific alert. It was working when it was in the main file, but when I moved it to the functions file, presentViewController is giving me an error, saying "Use of unresolved identifier 'presentViewController'." Please help! Here is my code:
in the functions file:
import Foundation
import UIKit
/**********************************************
Variables
***********************************************/
var canTapButton: Bool = false
var tappedAmount = 0
/**********************************************
Functions
***********************************************/
//the alert to ask the user to assess their speed
func showAlert(alert: String) -> Void
{
if(alert == "pleaseAssessAlert")
{
let pleaseAssessAlert = UIAlertController(title: "Welcome!", message: "If this is your firs time, I encourage you to use the Speed Assessment Tool (located in the menu) to figure which of you fingers is fastest!", preferredStyle: .Alert)
//ok button
let okButtonOnAlertAction = UIAlertAction(title: "Done", style: .Default)
{ (action) -> Void in
//what happens when "ok" is pressed
}
pleaseAssessAlert.addAction(okButtonOnAlertAction)
presentViewController(pleaseAssessAlert, animated: true, completion: nil)
}
else
{
println("Error calling the alert function.")
}
}
Thanks!
The presentViewController is the instance method of UIViewController class. So you can't access it on your function file like this.
You should change the function like:
func showAlert(alert : String, viewController : UIViewController) -> Void
{
if(alert == "pleaseAssessAlert")
{
let pleaseAssessAlert = UIAlertController(title: "Welcome!", message: "If this is your firs time, I encourage you to use the Speed Assessment Tool (located in the menu) to figure which of you fingers is fastest!", preferredStyle: .Alert)
//ok button
let okButtonOnAlertAction = UIAlertAction(title: "Done", style: .Default)
{ (action) -> Void in
//what happens when "ok" is pressed
}
pleaseAssessAlert.addAction(okButtonOnAlertAction)
viewController.presentViewController(pleaseAssessAlert, animated: true, completion: nil)
}
else
{
println("Error calling the alert function.")
}
}
Here, you are passing a UIViewController instance to this function and calling the presentViewController of that View Controller class.
In Swift 3:
The method presentViewController is replaced by present.
You can use it like the old one:
self.present(viewControllerToPresent, animated: true, completion: nil)
First, you need to check your NavigationController is appropriate or not?
If Yes, then Here is code for present and dismiss presentviewcontroller
For presenting PresentViewController :
let next = self.storyboard?.instantiateViewControllerWithIdentifier("Your view controller identifier") as! Yourviewcontroller
self.presentViewController(next, animated: true, completion: nil)
Dismiss Presentviewcontroller
self.dismissViewControllerAnimated(true, completion: nil)
I would say go with MidHun MP method above but, if you are looking for another way to do this without bringing in the UIViewController then:
func showAlert(alert : String) {
var window: UIWindow?
if(alert == "pleaseAssessAlert")
{
let pleaseAssessAlert = UIAlertController(title: "Welcome!", message: "If this is your firs time, I encourage you to use the Speed Assessment Tool (located in the menu) to figure which of you fingers is fastest!", preferredStyle: .Alert)
//ok button
let okButtonOnAlertAction = UIAlertAction(title: "Done", style: .Default)
{ (action) -> Void in
//what happens when "ok" is pressed
}
pleaseAssessAlert.addAction(okButtonOnAlertAction)
self.window?.rootViewController?.presentViewController(pleaseAssessAlert, animated: true, completion: nil)
}
else
{
println("Error calling the alert function.")
}
}
Presenting & navigation view controller has a problem with layoutsubviews function while using self.view or viewcontroller.view, so one must avoid those function.
Check:
func layoutsubviews not allows to provide the viewcontroller.view to work on it
All,
I am trying to write a method that will pass a closure to UIAlertAction such that when the OK button on an alert is tapped, both the alert and the calling view controller are dismissed.
What I have is:
func displayErrMsg( ecode : errorCodes ) ->() {
var etitle = ""
var etext = ""
var completionHandler: (()->())?
switch ecode {
case .NoError :
etitle = "Found You!"
etext = "Check your email for a link to reset your password"
completionHandler = { self.dismissViewControllerAnimated(true, { println("BUHBYE") })}
case .EmailAddressNotFound :
etitle = "Sorry, but we could not find you."
etext = "Have you registered?"
case .MalFormedEmailAddress :
etitle = "Opps!"
etext = "that is not a valid email address"
default : println(" unrecognized error code: \(ecode)")
}
userMessage( self, etitle, etext, completionHandler )
}
which calls this:
public func userMessage(parent: UIViewController, title:String, message:String, completion:(() ->())?) {
var okButton : UIAlertAction
var alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
if let comp = completion {
okButton = UIAlertAction(title: "Ok", style: .Default, handler: { (alert) -> Void in
comp()
})
}
else
{
okButton = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, nil)
}
alert.addAction(okButton)
parent.presentViewController(alert, animated: true, completion: nil)
}
In the scenario where the ecode is .NoError, I see the "BUHBYE" printed in the console,
but the view is not removed after the OK button is tapped (the alert is removed). From what I know, the view controller that should be dismissed by the closure is the one from which the displayErrorMsg
is called. Correct? Why doesn't this work?
Any and all help greatly appreciated.
:bp:
I'm not familiar yet with swift, but if the logic is the same as Objective-C, you may want to present this view controller on the didDismiss alert view call, not the clickedButton :
- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
Also note that you can not remove a view controller presenting an alert view from the hierarchy until the alert view is actually dismissed.