I am trying to create an alert view that performs a certain action when the button is clicked. I have tried creating a new class for the alert view, but when I try to add an action to the alert view controller, Xcode tells me that it is expecting a declaration, although the variable is declared just two steps above the line where the error occurs. Here's the code
class alerts: UIAlertController {
var alertThenGenerateNewThingController: UIAlertController = UIAlertController()
var generateNewThingOkButton = UIAlertAction (title: "OK", style: UIAlertActionStyle.Default) {
UIAlertAction in
println ("generate new thing action")
}
alertThenGenerateNewThingController.addAction (generateNewThingOkButton) // Here is where Xcode says it expected a declaration
func alertThenGenerateNewThing (alertTitle: String, alertMessage: String) {
alertThenGenerateNewThingController = UIAlertController (title: alertTitle, message: alertMessage, preferredStyle: .Alert)
self.presentViewController (alertThenGenerateNewThingController, animated: true, completion: nil)
}
}
You can't subclass UIAlertController, for one thing. Second of all, you can only interact with object properties inside of methods, functions, or the global scope. Run this code inside of the view controller where you plan on presenting your alert:
class viewController: UIViewController {
var alertThenGenerateNewThingController: UIAlertController = UIAlertController()
var generateNewThingOkButton = UIAlertAction (title: "OK", style: UIAlertActionStyle.Default) {
UIAlertAction in
println ("generate new thing action")
}
override func viewDidLoad() {
alertThenGenerateNewThingController.addAction(generateNewThingOkButton)
}
func alertThenGenerateNewThing (alertTitle: String, alertMessage: String) {
alertThenGenerateNewThingController = UIAlertController (title: alertTitle, message: alertMessage, preferredStyle: .Alert)
self.presentViewController (alertThenGenerateNewThingController, animated: true, completion: nil)
}
}
Related
Why I am getting Cannot find 'UIAlertController' in scope? error if i write alert function in separate swift file or if i use extension its not coming to another viewcontroller why?
code:
func showAlert(title: String, message: String) {
let alertController = UIAlertController(title: title, message:
message, preferredStyle: .alert)
alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: {action in
}))
self.present(alertController, animated: true, completion: nil)
}
error:
Cannot find 'UIAlertController' in scope,
Cannot find 'UIAlertAction' in scope
Cannot find 'self' in scope
Probably you forgot this in your viewController:
import UIKit
so your file has no idea what UIAlertController or UIAlertAction is
if you want to create an alert view controller to be used across multiple UIViewController you can do this:
import UIKit
class CustomAlertController: NSObject {
let message:String?
let title:String?
init(title:String, message:String) {
self.message = message
self.title = title
}
func showAlert()->UIAlertController {
let alertController = UIAlertController(title: self.title, message: self.message, preferredStyle: .alert)
// you can further customize your buttons, buttons' title etc
alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: {action in
}))
return alertController
}
}
then your view controllers
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let alert = CustomAlertController(title: "Hello", message: "My message to the world")
DispatchQueue.main.async {
self.present(alert.showAlert(), animated: true, completion: nil)
}
}
}
I would like to create an action sheet that can be used several time in my code. To do so, I need to be able to use functions according to the action sheet title. Is there a way to pass functions as a parameter array like the "title" parameter?
//MARK: - UIAlert action sheet title
enum ActionSheetLabel: String {
case camera = "Camera"
case photoLibrary = "Album"
case cancel = "Cancel"
}
class CameraHandler {
static let cameraHandler = CameraHandler()
func openCamera() { }
func openPhotoLibrary() { }
}
//MARK: - Alert that shows an action sheet with cancel
extension UIViewController {
func showActionSheetWithCancel(vc: UIViewController, title: [ActionSheetLabel] /*Make a function parameter here to match title*/) {
let actionSheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
for value in title {
actionSheet.addAction(UIAlertAction(title: value.rawValue, style: .default, handler: {
(alert: UIAlertAction!) -> Void in
//Use the parameter function here to match title
}))
}
actionSheet.addAction(UIAlertAction(title: ActionSheetLabel.cancel.rawValue, style: .cancel, handler: nil))
vc.present(actionSheet, animated: true, completion: nil)
}
}
For UIAlert you just need to change preferredStyle .alert it and it's working for UIAlert And and below code just copy and paste it working for UIActionSheet.
extension UIViewController {
func popupAlert(title: String?, message: String?, actionTitles:[String?], actionStyle:[UIAlertAction.Style], actions:[((UIAlertAction) -> Void)?]) {
let alert = UIAlertController(title: title, message: message, preferredStyle: .actionSheet)
for (index, title) in actionTitles.enumerated() {
let action = UIAlertAction(title: title, style: actionStyle[index], handler: actions[index])
alert.addAction(action)
}
self.present(alert, animated: true, completion: nil)
}
}
Check below code For Usage
self.popupAlert(title: "Alert"), message: “Error in Loading”, actionTitles: ["Okey", "Email"], actionStyle: [.default, .default], actions: [nil,{ action in
// I have set nil for first button click
// do your code for second button click
}])
if you have any query then please comment me. Thank You
I have find out the best way to add an action sheet with cancel and as much action as needed.
Create an UIViewController extension with type alias:
//MARK: - Alert that shows an action sheet with cancel
extension UIViewController {
typealias AlertAction = () -> ()
typealias AlertButtonAction = (ActionSheetLabel, AlertAction)
func showActionSheetWithCancel(titleAndAction: [AlertButtonAction]) {
let actionSheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
for value in titleAndAction {
actionSheet.addAction(UIAlertAction(title: value.0.rawValue, style: .default, handler: {
(alert: UIAlertAction!) -> Void in
value.1()
}))
}
actionSheet.addAction(UIAlertAction(title: ActionSheetLabel.cancel.rawValue, style: .cancel, handler: nil))
self.present(actionSheet, animated: true, completion: nil)
}
}
Then, in the class or other place where you want to use it, add the method this way:
//MARK: - UIAlert action sheet title
enum ActionSheetLabel: String {
case camera = "Camera"
case photoLibrary = "Album"
case cancel = "Cancel"
}
//MARK: - Class example where to use the action sheet action
class CameraHandler {
fileprivate let currentVC: UIViewController!
func openCamera() {
// Open user camera
}
func openPhotoLibrary() {
// Open user photo library
}
// Method example of this action sheet
func showActionSheetWithCameraAndLibrary(vc: UIViewController) {
//This is the way to use the extension
vc.showActionSheetWithCancel(titleAndAction: [
(ActionSheetLabel.camera, { [weak self] in self?.openCamera() }),
(ActionSheetLabel.photoLibrary, { [weak self] in self?.openPhotoLibrary() })
])
}
}
You can pass a closure and call it in the handler something like this should work.
Also not sure why you were passing the UIViewController , as you're already defining the function in a extension UIViewController therefore i allowed my self to remove it and used self.present instead .
extension UIViewController {
func showActionSheetWithCancel(title: [ActionSheetLabel], action: #escaping () -> ()?) {
let actionSheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
for value in title {
actionSheet.addAction(UIAlertAction(title: value.rawValue, style: .default, handler: {
(alert: UIAlertAction!) -> Void in
// action
action()
}))
}
let alertAction = UIAlertAction(title: ActionSheetLabel.cancel.rawValue, style: .cancel) { (_) in
action() // or for cancel call it here
}
actionSheet.addAction(alertAction)
self.present(actionSheet, animated: true, completion: nil)
}
}
As you can see #escaping () -> ()? is optional so you can pass nil too .
from what I understood you need to call a specific functions when the title of the alert changes & also you want to be able to do so from different viewControllers,
I hope this will help
extension UIViewController {
func showActionSheetWithCancel(vc: UIViewController, title: [ActionSheetLabel] ) {
let actionSheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
let cameraHandler = CameraHandler()
for value in title {
switch value.rawValue {
case ActionSheetLabel.camera.rawValue:
actionSheet.addAction(UIAlertAction(title: ActionSheetLabel.camera.rawValue, style: .default, handler: { (alert) in
cameraHandler.openCamera()
}))
case ActionSheetLabel.photoLibrary.rawValue:
actionSheet.addAction(UIAlertAction(title: ActionSheetLabel.photoLibrary.rawValue, style: .default, handler: { (alert) in
cameraHandler.openPhotoLibrary()
}))
default:
actionSheet.addAction(UIAlertAction(title: ActionSheetLabel.cancel.rawValue, style: .cancel, handler: nil))
}
vc.present(actionSheet, animated: true, completion: nil)
}
}
}
and the call of the function will be like this:
showActionSheetWithCancel(vc: self, title: [UIViewController.ActionSheetLabel.camera])
I have a UIViewController which loads up some json data from the server. If the server is down or the user has data turned off I throw up an alert telling the user such. This is done using a UIAlertController. This works great. So I put this into an extension since it is used by all UIViewControllers which need data. Now the UIAlertController has an action set as well
Alert code
extension UIViewController {
func connectionLost(){
var message = "Your device has lost connection to the server. Check that you have a valid internet connection and then retry."
let alertController = UIAlertController( title: "Connection Lost",
message: message,
preferredStyle: .alert)
let retryAction = UIAlertAction(title:"Retry", style: .default, handler: {
action in
//call function in the viewcontroller that raised this alert to reload the data
})
alertController.addAction(retryAction)
self.present(alertController, animated: true, completion: nil)
}
}
When the user taps the retry button I want to call a function in the uiviewcontroller that raised the alert.
I tried creating a delegate in the extension but struggled with getting it wired up like you do in a class. What sort of approaches are there to call a function from an extension in the viewcontroller that raised the alert?
You should create a BaseViewController and use Inheritance. It could be useful for other implementations too.
class BaseViewController: UIViewController {
func onRetryClick() {
// override to customize or write here the common behaviour
}
}
class FirstViewController: BaseViewController {
override func onRetryClick() {
// do something specific for FirstViewController
}
}
class SecondViewController: BaseViewController {
override func onRetryClick() {
// do something specific for SecondViewController
}
}
class ThirdViewController: BaseViewController {
// if you don't override this method, super class (BaseViewController) implementation will be executed
}
extension BaseViewController {
func connectionLost(){
var message = "Your device has lost connection to the server. Check that you have a valid internet connection and then retry."
let alertController = UIAlertController( title: "Connection Lost",
message: message,
preferredStyle: .alert)
let retryAction = UIAlertAction(title:"Retry", style: .default, handler: { action in
self.onRetryClick()
})
alertController.addAction(retryAction)
self.present(alertController, animated: true, completion: nil)
}
}
Hope this makes sense.
class MyVC: UIViewController {
func retry() {
}
func checkConnection() {
connectionLost { (retry) -> (Void) in
if retry {
self.retry()
}
}
}
}
extension UIViewController {
func connectionLost(completion: #escaping (_ retry: Bool) -> (Void)) {
let message = "Your device has lost connection to the server. Check that you have a valid internet connection and then retry."
let alertController = UIAlertController( title: "Connection Lost",
message: message,
preferredStyle: .alert)
let retryAction = UIAlertAction(title:"Retry", style: .default, handler: {
action in
completion(true)//may be 'false', you decide
})
alertController.addAction(retryAction)
self.present(alertController, animated: true, completion: nil)
}
}
I am having trouble calling the tweet function. I keep getting errors with the parameters. I also tried just (AnyObject) and got
Error: argument type does not conform to expected...
I am new to swift and not sure how to get this running. Tried everything I can think of. Thank you
// from GameScene
var vc = ViewController()
vc.tweetAction(sender: AnyObject)
//error: cannot create single-element tuple with an element label
//function in View Controller below
#IBAction func tweetAction(sender: AnyObject){
if SLComposeViewController.isAvailableForServiceType(SLServiceTypeTwitter){
let tweetController = SLComposeViewController(forServiceType: SLServiceTypeTwitter)
tweetController.setInitialText("I Scored on this app")
self.presentViewController(tweetController, animated: true, completion: nil)
}
else{
let alert = UIAlertController(title: "Accounts", message: "Please log into your twitter to share", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.Default, handler: nil))
alert.addAction(UIAlertAction(title: "Settings", style: UIAlertActionStyle.Default, handler: { (UIAlertACtion) in
let settingsURL = NSURL(string:UIApplicationOpenSettingsURLString)
if let url = settingsURL{
UIApplication.sharedApplication().openURL(url)
}
}))
self.presentViewController(alert, animated: true, completion: nil)
}
}
You are passing a type to your method invocation instead of an instance. You also are including a label for the first parameter, which is incorrect. Try:
vc.tweetAction(self)
Try to change sender parameter type from AnyObject to UILabel
var vc = ViewController()
vc.tweetAction(yourUILabelInstance)
And don't forget to modify tweetAction function as well
#IBAction func tweetAction(sender: UILabel){
...
}
I am trying to write an extension method that generates an UIAlertController based on what you give as a parameter.
extension UIAlertController {
func generate(messageText: String, messageTitle: String, buttonText: String) {
let alert = UIAlertController(title: messageTitle, message: messageText, preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: buttonText, style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)
}
}
This doesn't give an error.
But when I try to call it and add the parameter values
var alertTest = UIAlertController.generate("")
It gives the following error: Type 'UIAlertController' does not conform to protocol 'StringLiteralConvertible'
How can I fix this?
Or isn't it possible what i am trying to achieve?
There are some differences between how you have defined the generate method in the extension and how you are using it.
generate is declared as a function accepting 3 string parameters and returning void.
You are calling as a static method instead, passing one parameter, and expecting a return value.
The right way of using it is like this:
var alert = UIAlertController()
alert.generate("A Message", messageTitle: "A title", buttonText: "A button label")
However I think that the method implementation is incorrect, because you are creating a new instance of UIAlertController instead of (re)using the one the method is called on. What you probably need is a static method, in which case it should look like:
extension UIAlertController {
class func generate(# parent: UIViewController, messageText: String, messageTitle: String, buttonText: String) -> UIAlertController {
let alert = UIAlertController(title: messageTitle, message: messageText, preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: buttonText, style: UIAlertActionStyle.Default, handler: nil))
parent.presentViewController(alert, animated: true, completion: nil)
return alert
}
}
and used as:
var alert = UIAlertController.generate(parent: self, messageText: "A Message", messageTitle: "A title", buttonText: "A button label")