I'm extremely new to iOS. I'm trying to show a dialog to the user to get some input, but the actions are never triggered. I've been searching on the net for hours and no answer seem to work for me.
Here's the function I'm trying to use to show the dialog:
private func showAmountDialog(type: String, onComplete: #escaping (Double) -> Void) {
let alert = UIAlertController(title: "Enter an amount", message: nil, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: LzStrings.Common_Cancel, style: .cancel, handler: nil))
alert.addTextField(configurationHandler: { textField in
textField.placeholder = "0.00 \(type)"
textField.keyboardType = .decimalPad
})
alert.addAction(UIAlertAction(title: LzStrings.Common_OK, style: .default) { (UIAlertAction) in
if let input = alert.textFields?.first?.text, let amount = Double(input) {
print("Your amount: \(amount)")
}
})
self.present(alert, animated: true)
}
self here is my ViewController which has a parent of UIViewController type and several other protocols.
What I might be doing wrong?
EDIT: The way I knew it isn't executing is using break-points and not by relying on print("...")
Also, since I added the TextField right before adding the action, the nullability check is useless and the textFields.first is never nil, so in both cases, a break-point should be triggered or the print("...") should be executed, which neither of them is happening.
EDIT 2: Since the if statement can do a little distraction, I edited my code this way and tested again:
alert.addAction(UIAlertAction(title: LzStrings.Common_OK, style: .default) { (UIAlertAction) in
if let input = alert.textFields?.first {
if let amount = Double(input.text ?? "") {
print("Your amount: \(amount)")
} else {
print("Can't cast this string to double")
}
} else {
print("Text field is null")
}
})
Still, no feedback from the dialog.
PS: Even the Cancel button doesn't work.
EDIT 3: My dismiss function is overridden in the super class, but it passes completion closure normally:
override open func dismiss(animated flag: Bool, completion: (() -> Void)? = nil) {
if let navigationController = self.navigationController as? NavigationController {
navigationController.dismiss(animated: flag, completion: completion)
} else {
super.dismiss(animated: flag, completion: completion)
}
}
After having a conversation with one of my colleagues, we found out that to show standard UIAlertController we must use this:
self.view.window!.rootViewController?.present(alert, animated: true, completion: nil)
Instead of this
self.present(alert, animated: true, completion: nil)
It fixed my issue. I hope someone will find this helpful.
Another option is to use an extention for ViewController:
extension UIViewController {
//Show a basic alert
func showAlert(alertText : String, alertMessage : String) {
let alert = UIAlertController(title: alertText, message: alertMessage, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Got it", style: UIAlertActionStyle.default, handler: nil))
//Add more actions as you see fit
self.present(alert, animated: true, completion: nil)
}
}
Related
I want to have a base UIAlertController and I want to use it in different classes by just passing the buttons and their closures. To achieve this, I created an extension from UIAlertController like below:
extension UIAlertController {
func showAlert(buttons: [ButtonsAction]?) -> UIAlertController {
let alert = self
guard let alertButtons = buttons else {
return alert
}
for button in alertButtons {
let alertAction = UIAlertAction(title: button.title, style: button.style, handler: {action in
button.handler()
})
alert.addAction(alertAction)
}
return alert
}
}
for my buttons I have a struct:
struct ButtonsAction {
let title: String!
let style: UIAlertAction.Style
let handler: () -> Void
}
In one of my viewControllers I have a function which shows the alert. In that function I have a title and a message then I want to have 1 button to dismiss the alert. The function is something like this:
func fetchFaild(title: String, message: String) {
let buttons = ButtonsAction.init(title: "cancel", style: .cancel, handler: {action in
//here I want to dissmiss the alert I dont know how
})
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert).showAlert(buttons: buttons)
alert.show(self, sender: nil)
}
I have problem adding buttons to the Alert and I don't know how to add actions to the buttons.
I know this is not the best practice here. If any one knows any example or any tutorial that can help me achieve this I really appreciate it.
An extension of UIViewController might be a more reasonable solution and the ButtonsAction struct seems to be redundant.
extension UIViewController {
func showAlert(title: String, message: String, actions: [UIAlertAction], completion: (() -> Void)? = nil) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
actions.forEach{alertController.addAction($0)}
self.present(alertController, animated: true, completion: completion)
}
}
class MyController : UIViewController {
func fetchFailed(title: String, message: String) {
let actions = [UIAlertAction(title: "Cancel", style: .cancel, handler: { (action) in
print("Cancel tapped")
})]
showAlert(title: title, message: message, actions: actions)
}
}
I would like to add a method to my ViewController that shows a message with text as an alert with a Yes and a No button. The result should be of type Bool (Yes/No).
What I have tried is the following:
func YesNoBox(msg: String) -> Bool
{
var retVal = false
let alert = UIAlertController(title: "", message: msg, preferredStyle: .alert)
let action_yes = UIAlertAction(title: "Yes", style: .default, handler:
{ _ in NSLog("The \"Yes\" alert occured."); retVal = true })
let action_no = UIAlertAction(title: "No", style: .cancel, handler:
{ _ in NSLog("The \"No\" alert occured."); retVal = false })
alert.addAction(action_yes)
alert.addAction(action_no)
self.present(alert, animated: true, completion: nil)
return retVal
}
However, the value of retVal is always false. If I was in C/C++, I guess I could resolve this issue with a pointer, but this is Swift (and I am pretty new to this).
Any idea anyone how I could get this working?
EDIT: The problem that I have is the following. On a ViewController I have a TextField. When I tap on the text field, the app should ask the user whether they want to paste the text from the clipboard. If yes, paste, otherwise give the TextField the focus (i.e. let the cursor blink in it). I tried to do this with 'textFieldShouldBeginEditing' and in this method I display the YesNoBox. The problem is that the TextField never gets the focus after the YesNoBox is closed. And when I use 'becomeFirstResponder()' after the Box call, the app freezes. I don't know what to do?
Use a completion
func yesNoBox(msg: String,completion:#escaping(Bool) -> ())
{
let alert = UIAlertController(title: "", message: msg, preferredStyle: .alert)
let action_yes = UIAlertAction(title: "Yes", style: .default, handler:
{ _ in
NSLog("The \"Yes\" alert occured.");
completion(true)
})
let action_no = UIAlertAction(title: "No", style: .cancel, handler:
{ _ in
NSLog("The \"No\" alert occured.");
completion(false)
})
alert.addAction(action_yes)
alert.addAction(action_no)
self.present(alert, animated: true, completion: nil)
}
call
yesNoBox(msg:"someMessage") { yes in
if yes {
// do yes action
}
else {
// do no action
}
}
2 Callbacks:
This function has 2 completions ( imagine we have a function that uploads an image and notifies the progress with a completion and another 1 to say done )
func uploadImage(data: Data,progress:#escaping(Float) -> (),completion:#escaping(Bool) -> ()) {
// implementation here
}
To call
self.uploadImage(someData) { progress in
print(progress)
}) { done in
print(done)
}
This can be achieved with completion handlers.
func showAlertWithOptions(title: String, message: String, completionHandler: #escaping (Bool) -> Void) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
let action_yes = UIAlertAction(title: "Yes", style: .default, handler: { _ in
completionHandler(true)
})
let action_no = UIAlertAction(title: "No", style: .cancel, handler: { _ in
completionHandler(false)
})
alert.addAction(action_yes)
alert.addAction(action_no)
self.present(alert, animated: true, completion: nil)
}
Now call the function and add any other functions or actions that you want to perform depending on the action selected.
showAlertWithOptions(title: "Any title", message: "Any message") { success in
if success {
NSLog("The \"Yes\" alert occured.")
} else {
NSLog("The \"No\" alert occured.")
}
}
I've got a Problem. I'm new to iOS programming, and i'm struggling to understand how Swift code is excecuted. For example, in the piece of code below, I would think that every line is executed right after the one above. But when it reaches the passData() function, it does not ejecute that fuction. it keeps going, and some time later (or erlier) it excecutes it (the passData function).
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if numLaunches == 0{
nombre = usuario()
numLaunches += 1
}
}
func usuario() -> String {
var tField: UITextField!
func configurationTextField(textField: UITextField!)
{
print("generating the TextField")
textField.placeholder = "Enter an item"
textField.textAlignment = .center
tField = textField
}
func handleCancel(alertView: UIAlertAction!)
{
print("Cancelled !!")
}
let alert = UIAlertController(title: "Please Enter Your Name", message: "", preferredStyle: .alert)
alert.addTextField(configurationHandler: configurationTextField)
alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler:handleCancel))
alert.addAction(UIAlertAction(title: "Done", style: .default, handler:{ (UIAlertAction) in
print("Done !!")
print("Item : \(String(describing: tField.text))")
self.nombre = tField.text!
}))
self.present(alert, animated: true, completion: {
print("completion block")
})
print(self.nombre)
passData()
if tField.text == nil {
return "No value"
}else{
return (tField.text!)
}
}
func passData() {
let myVC = storyboard?.instantiateViewController(withIdentifier: "SecondVC") as! AboutViewController
if myVC.playerName != nil {
myVC.playerName.text = nombre
}else{
}
navigationController?.pushViewController(myVC, animated: true)
print("pasa el dato")
}
So, the Problem is, that i need to pass the content of the variable "nombre" to another VC. But when the passData function is excecuted that variable is empty. I thought if i called that function after the variable was updated, it Will pass the right content. But im clearly mistaken.
I would appreciate the help!
In general, unless your functions are asynchronous, you are correct in your understanding that code is executed from top down. In this case I think you are just confused about your UIAlertAction code. It appears you are popping an alert to the user, asking them to write their name, and when they hit "Done" you want to call your passData() function. In that case, you should put that passData() call inside your UIAlertAction, like so:
alert.addAction(UIAlertAction(title: "Done", style: .default, handler:{ (UIAlertAction) in
print("Done !!")
print("Item : \(String(describing: tField.text))")
self.nombre = tField.text!
self.passData()
}))
The code inside the handler for your UIAlertActions will not be executed until the user presses that button, which is why you are finding that passData is getting called too early.
I want to make a function in NSObject class for UIAlertCotroller. So that I can access this function in any class. I have tried with that following code:
open class func showActionSheet(_ delegate: UIViewController, message: String, strtittle: String, handler: ((UIAlertController) -> Void)! = nil)
{
let actionSheetController: UIAlertController = UIAlertController(title: strtittle, message: message, preferredStyle: UIAlertControllerStyle.actionSheet)
if handler == nil{
actionSheetController.addAction(UIAlertAction(title: "Default(Off)" , style: .default , handler:{ (UIAlertAction)in
}))
}
else{
actionSheetController.addAction(UIAlertAction(title: "Default(Off)" , style: .default , handler:{ (UIAlertAction)in
}))
}
delegate.present(actionSheetController, animated: true, completion: {
print("completion block")
})
}
This is the function that I made, but problem is there can be number of actions in ActionSheet and they also have different tittle and different styles.
Question: How can I make this function? Please Help.
Thanks!
Make extension of UIAlertController
extension UIAlertController{
func AlertWithTextField(_ view:UIViewController) -> UIAlertController{
let actionSheetController: UIAlertController = UIAlertController(title: "Action Sheet", message: message, preferredStyle: UIAlertControllerStyle.actionSheet)
actionSheetController.addAction(UIAlertAction(title: "No" , style: .default , handler:{ (UIAlertAction)in
}))
actionSheetController.addAction(UIAlertAction(title: "Yes" , style: .default , handler:{ (UIAlertAction)in
}))
view.present(actionSheetController, animated: true, completion: {
print("completion block")
})
return actionSheetController
}
}
Call this from your ViewController
let alert = UIAlertController()
alert.AlertWithTextField(self)
I have found solution of my problem by using this Swift - How to present ViewController when tapping button in a custom AlertController
Their are following modification that I have to do to achieve my goal. Here is the code:
In Controller Class:
Alert.showActionSheet(self, message: "Save incoming media for this chat",strtittle: "",actionTittle: ["Default(Off)","Always","Never","Cancel"],
actionStyle: [.default,.default,.default,.cancel] ,
withHandler: [defaultHandler, alwaysHandler, neverHandler, cancelHandler])
func defaultHandler(action: UIAlertAction) {
//Add code of present
print("DefaultHandler")
}
func alwaysHandler(action: UIAlertAction) {
//Add code of present
print("alwaysHandler")
}
func neverHandler(action: UIAlertAction) {
//Add code of present
print("neverHandler")
}
func cancelHandler(action: UIAlertAction) {
//Add code of present
print("cancelHandler")
}
In NSObject Class:
open class func showActionSheet(_ delegate: UIViewController, message: String, strtittle: String, actionTittle: [String], actionStyle: [UIAlertActionStyle], withHandler handler: [((UIAlertAction) -> Void)]?)
{
var actionSheetController: UIAlertController = UIAlertController()
if message != "" || strtittle != ""
{
actionSheetController = UIAlertController(title: strtittle, message: message, preferredStyle: UIAlertControllerStyle.actionSheet)
}
for i in 0..<actionTittle.count
{
actionSheetController.addAction(UIAlertAction(title: actionTittle[i],
style: actionStyle[i],
handler: handler?[i]))
}
delegate.present(actionSheetController, animated: true, completion: nil)
}
Using this I can gave number of actions, their tittle and styles to action sheet. And also I can simply call this method in each class. :)
I have various controllers in my app that all require validation, and when validation fails, I want to display an alert with the errors. Is there some best practice/design pattern for doing this? I could simply create a static function in a Helper class like so:
static func displayAlert(message: String, buttonTitle: String, vc: UIViewController)
{
let alertController = UIAlertController(title: "", message: message, preferredStyle: .Alert)
let okAction = UIAlertAction(title: buttonTitle, style: .Default, handler: nil)
alertController.addAction(okAction)
vc.presentViewController(alertController, animated: true, completion: nil)
}
But then I need to pass the view controller..which seems like bad practice. I could shoot off a notification and observe it, but that seems like overkill. Am I overthinking this, or is there some more acceptable way to go about handling something like this?
I ended up creating an extension for UIViewController and creating the alert function there:
extension UIViewController {
func alert(message: String, title: String = "") {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alertController.addAction(OKAction)
self.present(alertController, animated: true, completion: nil)
}
}
Swift 4
I wanted this same functionality for myself, so I made a full extension. To use it, create a new swift file in your project and name it whatever you'd like. Place the following code inside:
import UIKit
extension UIViewController {
func presentAlertWithTitle(title: String, message: String, options: String..., completion: #escaping (Int) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
for (index, option) in options.enumerated() {
alertController.addAction(UIAlertAction.init(title: option, style: .default, handler: { (action) in
completion(index)
}))
}
self.present(alertController, animated: true, completion: nil)
}
}
To use it (which so many people don't actually show, which can lead to confusion for a newbie like myself):
presentAlertWithTitle(title: "Test", message: "A message", options: "1", "2") { (option) in
print("option: \(option)")
switch(option) {
case 0:
print("option one")
break
case 1:
print("option two")
default:
break
}
}
As original answer from itstrueimryan at https://stackoverflow.com/a/30714429/6822183
Update for Swift 3:
extension UIViewController {
func alert(message: String, title: String = "") {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
let OKAction = UIAlertAction(title: "OK", style: .default, handler: nil)
alertController.addAction(OKAction)
self.present(alertController, animated: true, completion: nil)
}
}
I may have found a better answer to this problem, via an article by Krakendev: https://krakendev.io/blog/subclassing-can-suck-and-heres-why.
The idea is to use protocol-oriented programming to create a default implementation of an alert just for UIViewControllers:
protocol Alertable {
func issueAlert()
}
extension Alertable where Self: UIViewController {
func issueAlert() {
// alert code here
}
}
Now, just like that, every UIViewController that adheres to Alertable will have the issueAlert() method available to them without even having to define its own implementation.
And, of course, we can define parameters for the issueAlert function as well:
extension Alertable where Self: UIViewController {
func issueAlert(title: "Default Title", message: String = "Default Message") {
// alert code here
}
}
So our view controller can do either:
issueAlert()
or
issueAlert(title: "Error", message: "Something went wrong")
Two advantages to this approach that I can think of are that you know if a view controller has access to this method just by looking at the Alertable protocol in the class definition, and individual view controllers can override this method if they want to provide custom functionality. Of course, now you can also specify the Alertable contract as a method parameter.
Answer from Sigex is completely fine, except the int indices passing to trace the button clicks might not make sense because, caller needed to keep track with int value. In that case passing string arguments and comparing them in switch case in completion block makes more sense to me. I would rather use like,
import UIKit
extension UIViewController {
func presentAlertWithTitle(title: String, message: String, options: String..., completion: #escaping (String) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
for (index, option) in options.enumerated() {
alertController.addAction(UIAlertAction.init(title: option, style: .default, handler: { (action) in
completion(options[index])
}))
}
self.present(alertController, animated: true, completion: nil)
}
}
And test with,
class TestViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
presentAlertWithTitle(title: "Test", message: "A sample message", options: "start", "stop", "cancel") { (option) in
print("option: \(option)")
switch(option) {
case "start":
print("start button pressed")
break
case "stop":
print("stop button pressed")
break
case "cancel":
print("cancel button pressed")
break
default:
break
}
}
}
}
Why not create a Utility function that returns the AlertView to the ViewController?
self.presentViewController(Utilities.createAlertController("errorMessage"), animated: true, completion: nil);
Updated for swift 3:
if you want to show the alert message to user used below simple lines of code;
// function defination:
func showMessageToUser(title: String, msg: String) {
let alert = UIAlertController(title: title, message: msg, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
//function call :
self.showMessageToUser(title: "Alert", msg: "your message to user")
// Enjoy coding..!
I used Sigex's extension in my code, however I have added a check, if options were used or not.
If no options are given in the call, then the Alert only shows "OK" and completes with returning option 0.
extension UIViewController {
func presentAlertWithTitle(title: String, message: String, options: String..., completion: #escaping (Int) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
if options.count == 0 {
let OKAction = UIAlertAction(title: "OK", style: .default, handler: { (action) in
completion(0)
})
alertController.addAction(OKAction)
} else {
for (index, option) in options.enumerated() {
alertController.addAction(UIAlertAction.init(title: option, style: .default, handler: { (action) in
completion(index)
}))
}
}
self.present(alertController, animated: true, completion: nil)
}
}
Just omit the part , options: "1","2" then default alert is shown.
I love Sigex's extension, but I spiced it up a bit to add style on button depending on the title
func presentAlertWithOptions(title: String, message: String, options: String..., completion: #escaping (Int) -> Void) {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
if options.count == 0 { //if there is no options, show a basic alert
let OKAction = UIAlertAction(title: "OK", style: .default, handler: { (action) in
completion(0)
})
alertController.addAction(OKAction)
} else { //alert with options
for (index, option) in options.enumerated() {
var alertStyle = UIAlertAction.Style.default
switch option { //check if we should style the buttons
case "Cancel": //cancel style
alertStyle = .cancel
case "Logout", "Discard Changes", "Discard", "Delete", "Remove": //destructive style
alertStyle = .destructive
default: break //keep as default
}
alertController.addAction(UIAlertAction(title: option, style: alertStyle, handler: { (action) in
completion(index)
}))
}
}
self.present(alertController, animated: true, completion: nil)
}
Swift 4.1
let alert = UIAlertController(title: "Atenção",message: "Mensagem Aqui",preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
self.present(alert, animated: true)