I am creating an app with one of the tab being a guestbook where users can write something. I use an UIAlertController to pop up a window with a textfield for entering name, and a textview for entering the message. I want to make the "Post" button disabled by default, then enable it after the name field has at least 2 characters and the message has at least 3 characters. I have achieved this by
#1: declare the "Post" UIAlertAction at the top
let saveAction = UIAlertAction(title:"Post", style: .default, handler: { (action) -> Void in print(data) })
The above line gives the error (Cannot use instance member 'data' within property initializer; property initializers run before self is available.)
#2: add this "Post" button in alert and making it disabled
alert.addAction(saveAction)
saveAction.isEnabled = false
#3 add two functions to detect how many words are in the textfield and textview, and if they meet the requirement, enable the "Post" button
func textViewDidChange(_ textView: UITextView) { //Handle the text changes here
GuestbookContentWordCount = textView.text.count
data["content"] = textView.text
enableSave()
}
#objc func textFieldDidChange(_ textField: UITextField) {
GuestbookNameWordCount = textField.text?.count ?? 0
data["name"] = textField.text
enableSave()
}
func enableSave () {
if GuestbookContentWordCount >= 3 && addGuestbookNameWordCount >= 2 {
saveAction.isEnabled = true
} else {
saveAction.isEnabled = false
}
}
The ideal situation is when the requirements are met and the user clicks on the "Post" button, I will get the data["name"] and data["content"] and insert it into a database. Right now I have gotten it to work to the point that the "Post" button is enabled after the requirements are met, but when trying to get the data it gives the error "Cannot use instance member 'data' within property initializer; property initializers run before self is available.
Can you please advise how to solve this problem? Thank you.
So this is what I would do
Change your UIAlertAction reference to this outside the viewDidLoad()
var saveAction: UIAlertAction? = nil
Inside the viewDidLoad() you can instantiate it like:
saveAction = UIAlertAction(title:"Post", style: .default, handler: { [weak self] (action) -> Void in
guard let `self` = self else { return }
print(self.data) }
)
[weak self] is used so that you don't end up having retain cycles after your UIViewController is deinitialised.
Related
I'm programmatically adding a UITapGestureRecognizer to one of my views:
let gesture = UITapGestureRecognizer(target: self, action: #selector(self.handleTap(modelObj:myModelObj)))
self.imageView.addGestureRecognizer(gesture)
func handleTap(modelObj: Model) {
// Doing stuff with model object here
}
The first problem I encountered was "Argument of '#selector' does not refer to an '#Objc' method, property, or initializer.
Cool, so I added #objc to the handleTap signature:
#objc func handleTap(modelObj: Model) {
// Doing stuff with model object here
}
Now I'm getting the error "Method cannot be marked #objc because the type of the parameter cannot be represented in Objective-C.
It's just an image of the map of a building, with some pin images indicating the location of points of interest. When the user taps one of these pins I'd like to know which point of interest they tapped, and I have a model object which describes these points of interest. I use this model object to give the pin image it's coordinates on the map so I thought it would have been easy for me to just send the object to the gesture handler.
It looks like you're misunderstanding a couple of things.
When using target/action, the function signature has to have a certain form…
func doSomething()
or
func doSomething(sender: Any)
or
func doSomething(sender: Any, forEvent event: UIEvent)
where…
The sender parameter is the control object sending the action message.
In your case, the sender is the UITapGestureRecognizer
Also, #selector() should contain the func signature, and does NOT include passed parameters. So for…
func handleTap(sender: UIGestureRecognizer) {
}
you should have…
let gesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(sender:)))
Assuming the func and the gesture are within a view controller, of which modelObj is a property / ivar, there's no need to pass it with the gesture recogniser, you can just refer to it in handleTap
Step 1: create the custom object of the sender.
step 2: add properties you want to change in that a custom object of the sender
step 3: typecast the sender in receiving function to a custom object and access those properties
For eg:
on click of the button if you want to send the string or any custom object then
step 1: create
class CustomButton : UIButton {
var name : String = ""
var customObject : Any? = nil
var customObject2 : Any? = nil
convenience init(name: String, object: Any) {
self.init()
self.name = name
self.customObject = object
}
}
step 2-a: set the custom class in the storyboard as well
step 2-b: Create IBOutlet of that button with a custom class as follows
#IBOutlet weak var btnFullRemote: CustomButton!
step 3: add properties you want to change in that a custom object of the sender
btnFullRemote.name = "Nik"
btnFullRemote.customObject = customObject
btnFullRemote.customObject2 = customObject2
btnFullRemote.addTarget(self, action: #selector(self.btnFullRemote(_:)), for: .touchUpInside)
step 4: typecast the sender in receiving function to a custom object and access those properties
#objc public func btnFullRemote(_ sender: Any) {
var name : String = (sender as! CustomButton).name as? String
var customObject : customObject = (sender as! CustomButton).customObject as? customObject
var customObject2 : customObject2 = (sender as! CustomButton).customObject2 as? customObject2
}
Swift 5.0 iOS 13
I concur a great answer by Ninad. Here is my 2 cents, the same and yet different technique; a minimal version.
Create a custom class, throw a enum to keep/make the code as maintainable as possible.
enum Vs: String {
case pulse = "pulse"
case precision = "precision"
}
class customTap: UITapGestureRecognizer {
var cutomTag: String?
}
Use it, making sure you set the custom variable into the bargin. Using a simple label here, note the last line, important labels are not normally interactive.
let precisionTap = customTap(target: self, action: #selector(VC.actionB(sender:)))
precisionTap.customTag = Vs.precision.rawValue
precisionLabel.addGestureRecognizer(precisionTap)
precisionLabel.isUserInteractionEnabled = true
And setup the action using it, note I wanted to use the pure enum, but it isn't supported by Objective C, so we go with a basic type, String in this case.
#objc func actionB(sender: Any) {
// important to cast your sender to your cuatom class so you can extract your special setting.
let tag = customTag as? customTap
switch tag?.sender {
case Vs.pulse.rawValue:
// code
case Vs.precision.rawValue:
// code
default:
break
}
}
And there you have it.
cell.btn.tag = indexPath.row //setting tag
cell.btn.addTarget(self, action: #selector(showAlert(_ :)), for: .touchUpInside)
#objc func showAlert(_ sender: UIButton){
print("sender.tag is : \(sender.tag)")// getting tag's value
}
Just create a custom class of UITapGestureRecognizer =>
import UIKit
class OtherUserProfileTapGestureRecognizer: UITapGestureRecognizer {
let userModel: OtherUserModel
init(target: AnyObject, action: Selector, userModel: OtherUserModel) {
self.userModel = userModel
super.init(target: target, action: action)
}
}
And then create UIImageView extension =>
import UIKit
extension UIImageView {
func gotoOtherUserProfile(otherUserModel: OtherUserModel) {
isUserInteractionEnabled = true
let gestureRecognizer = OtherUserProfileTapGestureRecognizer(target: self, action: #selector(self.didTapOtherUserImage(_:)), otherUserModel: otherUserModel)
addGestureRecognizer(gestureRecognizer)
}
#objc internal func didTapOtherUserImage(_ recognizer: OtherUserProfileTapGestureRecognizer) {
Router.shared.gotoOtherUserProfile(otherUserModel: recognizer.otherUserModel)
}
}
Now use it like =>
self.userImageView.gotoOtherUserProfile(otherUserModel: OtherUserModel)
You can use an UIAction instead:
self.imageView.addAction(UIAction(identifier: UIAction.Identifier("imageClick")) { [weak self] action in
self?.handleTap(modelObj)
}, for: .touchUpInside)
that may be a terrible practice but I simply add whatever I want to restore to
button.restorationIdentifier = urlString
and
#objc func openRelatedFact(_ sender: Any) {
if let button = sender as? UIButton, let stringURL = factButton.restorationIdentifier, let url = URL(string: stringURL) {
if UIApplication.shared.canOpenURL(url) {
UIApplication.shared.open(url, options: [:])
}
}
}
Is it possible, with a UIAlert, to return what the user selected to a delegate method? If so, how?
I'd prefer not to change the delegate method or stop using UIAlert, if such a solution exists. Though all help and ideas are appreciated.
Delegate Protocol
protocol RouteManagerDelegate {
//behaves like textFieldShouldEndEditing
func routeShouldUpdateUnfinished() -> Bool
}
My Current Attempt at Implementation
extension MyController : RouteManagerDelegate {
func routeShouldUpdateUnfinished() -> Bool {
var response = false
//make Alert
let confirmationAlert = UIAlertController(title: "Current Route is Unfinished", message: "Do you want to continue?", preferredStyle: .alert)
//add Yes or No options
confirmationAlert.addAction(UIAlertAction(title: "Yes", style: .destructive) { _ in
response = true
})
confirmationAlert.addAction(UIAlertAction(title: "No", style: .cancel)
self.present(confirmationAlert, animated: true)
return response
}
}
This doesn't work because UIAlert behaves asynchronously. The function simply returns false every time.
But you can clearly see the intent:
If the user selects 'Yes' (continue), then routeShouldUpdateUnfinished should return true.
For me the provided code looks like the delegate method is being understood wrong. To help you out a little, here a little diagram:
The delegate pattern is used to communicate from child to parent.
In your solution this could look like:
Parent implements delegate pattern with function
func routeShouldUpdateUnfinished(result: bool) { ... }
When parent sets child up the parent calls
child.delegate = self
The alert inside child calls
delegate.routeShouldUpdateUnfinished(true)
The parent handles the code
Just in case someone finds themselves in this esoteric position:
I wanted to do as Ramden suggested, but also didn't want to expose a function that other classes should never use (except in this scenario).
I ended up using a default implementation for my delegate method (defined in an extension of my protocol) and a static fileprivate method to handle the result of my delegate method returning true.
Now the fileprivate 'handler' method isn't exposed but I can also use a UIAlert. This has flaws but works. Implementation below, if ever it's useful to someone.
protocol RouteManagerDelegate {
func routeShouldUpdateUnfinished() -> Bool
}
extension RouteManagerDelegate { //default implementations of delegate protocol
func routeShouldUpdateUnfinished() -> Bool {
if let delegate = self as? UIViewController {
let alert = UIAlertController(title: "Wait!", message: "Do you want to continue?", preferredStyle: .alert)
confirmationAlert.addAction(UIAlertAction(title: "Yes", style: .destructive) { _ in
RouteManager.handleRouteChangedUnfinished() //the 'handler' function
})
confirmationAlert.addAction(UIAlertAction(title: "No", style: .cancel))
delegate.present(confirmationAlert, animated: true)
}
return false
}
}
struct RouteManager {
func myFunc() {
...
if delegate?.routeShouldUpdateUnfinished() ?? true {
RouteManager.handleRouteChangedUnfinished() //the 'handler' function
}
...
}
static fileprivate func handleRouteChangedUnfinished() { //don't want to expose this
//Notify the Database
}
}
I have buttons in the storyboard that I put into a Referencing Outlet Collection. I'm using UITapGestureRecognizer and UILongPressGestureRecognizer for all of these buttons, but how can I print exactly which button gets tapped? Bellow is what I tried but doesn't work. I get an error that says "Value of type 'UILongPressGestureRecognizer' has no member 'tag'." I'm trying to build the button grid for the Minesweeper game. Thank you for your help.
class ViewController: UIViewController {
#IBOutlet var testButtons: [UIButton]! // There are 100 buttons in this array
override func viewDidLoad() {
super.viewDidLoad()
let testButtonPressed = UILongPressGestureRecognizer(target: self, action: #selector(testPressed))
testButtonPressed.minimumPressDuration = 0.5
// These indexes are just to test how to recognize which button gets pressed
testButtons[0].addGestureRecognizer(testButtonPressed)
testButtons[1].addGestureRecognizer(testButtonPressed)
}
#objc func testPressed(_ sender: UILongPressGestureRecognizer) {
print("Test button was pressed")
print(sender.tag) // THIS DOESN'T WORK, BUT CONCEPTUALLY THIS IS WHAT I WANT TO DO
}
This error occurs because UILongPressGestureRecognizer object has no tag property
You can access sender's button in a way like that:
#objc func testPressed(_ sender: UILongPressGestureRecognizer) {
guard let button = sender.view as? UIButton else { return }
print(button.tag)
}
I think that the best solution to handle button's actions is to add #IBAction
(you can add it like #IBOutlet with a minor change - set Action connection type)
And then in #IBAction block you cann access all button properties (like tag and others)
instead of using gesture I think it would be better to use #IBAction and connect the buttons With it here is a small example
UILongPressGestureRecognizer which is a subclass of UIGestureRecognizer, can be used only once per button or view. Because UILongPressGestureRecognizer has only a single view property. In your code, it will always be testButtons[1] calling the testPressed action. So you have to first modify the viewDidLoad code like this :-
for button in testButtons {
let testButtonPressed = UILongPressGestureRecognizer(target: self, action: #selector(testPressed))
testButtonPressed.minimumPressDuration = 0.5
button.addGestureRecognizer(testButtonPressed)
button.addGestureRecognizer(testButtonPressed)
}
Then you can access the button from testPressed like this (I hope you've already set the tag in the storyboard) :-
#objc func testPressed(_ sender: UILongPressGestureRecognizer) {
if sender.state == .began {
if let button = sender.view as? UIButton {
print(button.tag)
}
}
}
You need to set tags before pressing!
On the viewDidLoad() method you must add something like:
testButtons.enumerated().forEach {
let testButtonPressed = UILongPressGestureRecognizer(target: self, action: #selector(testPressed))
testButtonPressed.minimumPressDuration = 0.5
$0.element.addGestureRecognizer(testButtonPressed)
$0.element.tag = $0.offset
}
And when the long press is receiving you need to get a tag from view not from the sender!
print(sender.view?.tag)
Since a gesture recognizer should only be associated with a single view, and doesn't directly support using an identity tag to match it with buttons. When creating an array of buttons for a keyboard, with a single gesture response function, I found it easier to use the gesture recognizer "name" property to identify the associated button.
var allNames: [String] = []
// MARK: Long Press Gesture
func addButtonGestureRecognizer(button: UIButton, name: String) {
let longPrssRcngr = UILongPressGestureRecognizer.init(target: self, action: #selector(longPressOfButton(gestureRecognizer:)))
longPrssRcngr.minimumPressDuration = 0.5
longPrssRcngr.numberOfTouchesRequired = 1
longPrssRcngr.allowableMovement = 10.0
longPrssRcngr.name = name
allNames.append(name)
button.addGestureRecognizer(longPrssRcngr)
}
// MARK: Long Key Press
#objc func longPressOfButton(gestureRecognizer: UILongPressGestureRecognizer) {
print("\nLong Press Button => \(String(describing: gestureRecognizer.name)) : State = \(gestureRecognizer.state)\n")
if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
if let keyName = gestureRecognizer.name {
if allNames.contains(keyName) {
insertKeyText(key: keyName)
} else {
print("No action available for key")
}
}
}
}
To implement, call the addButtonGestureRecognizer function after creating the button, and provide a name for the button (I used the button text) e.g.
addButtonGestureRecognizer(button: keyButton, name: buttonText)
The button name is stored in the "allNames" string array so that it can be matched later in "longPressOfButton".
When the button name is matched in the "longPressOfButton" response function, it passes it to "addKeyFunction" where it is processed.
I'm programmatically adding a UITapGestureRecognizer to one of my views:
let gesture = UITapGestureRecognizer(target: self, action: #selector(self.handleTap(modelObj:myModelObj)))
self.imageView.addGestureRecognizer(gesture)
func handleTap(modelObj: Model) {
// Doing stuff with model object here
}
The first problem I encountered was "Argument of '#selector' does not refer to an '#Objc' method, property, or initializer.
Cool, so I added #objc to the handleTap signature:
#objc func handleTap(modelObj: Model) {
// Doing stuff with model object here
}
Now I'm getting the error "Method cannot be marked #objc because the type of the parameter cannot be represented in Objective-C.
It's just an image of the map of a building, with some pin images indicating the location of points of interest. When the user taps one of these pins I'd like to know which point of interest they tapped, and I have a model object which describes these points of interest. I use this model object to give the pin image it's coordinates on the map so I thought it would have been easy for me to just send the object to the gesture handler.
It looks like you're misunderstanding a couple of things.
When using target/action, the function signature has to have a certain form…
func doSomething()
or
func doSomething(sender: Any)
or
func doSomething(sender: Any, forEvent event: UIEvent)
where…
The sender parameter is the control object sending the action message.
In your case, the sender is the UITapGestureRecognizer
Also, #selector() should contain the func signature, and does NOT include passed parameters. So for…
func handleTap(sender: UIGestureRecognizer) {
}
you should have…
let gesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(sender:)))
Assuming the func and the gesture are within a view controller, of which modelObj is a property / ivar, there's no need to pass it with the gesture recogniser, you can just refer to it in handleTap
Step 1: create the custom object of the sender.
step 2: add properties you want to change in that a custom object of the sender
step 3: typecast the sender in receiving function to a custom object and access those properties
For eg:
on click of the button if you want to send the string or any custom object then
step 1: create
class CustomButton : UIButton {
var name : String = ""
var customObject : Any? = nil
var customObject2 : Any? = nil
convenience init(name: String, object: Any) {
self.init()
self.name = name
self.customObject = object
}
}
step 2-a: set the custom class in the storyboard as well
step 2-b: Create IBOutlet of that button with a custom class as follows
#IBOutlet weak var btnFullRemote: CustomButton!
step 3: add properties you want to change in that a custom object of the sender
btnFullRemote.name = "Nik"
btnFullRemote.customObject = customObject
btnFullRemote.customObject2 = customObject2
btnFullRemote.addTarget(self, action: #selector(self.btnFullRemote(_:)), for: .touchUpInside)
step 4: typecast the sender in receiving function to a custom object and access those properties
#objc public func btnFullRemote(_ sender: Any) {
var name : String = (sender as! CustomButton).name as? String
var customObject : customObject = (sender as! CustomButton).customObject as? customObject
var customObject2 : customObject2 = (sender as! CustomButton).customObject2 as? customObject2
}
Swift 5.0 iOS 13
I concur a great answer by Ninad. Here is my 2 cents, the same and yet different technique; a minimal version.
Create a custom class, throw a enum to keep/make the code as maintainable as possible.
enum Vs: String {
case pulse = "pulse"
case precision = "precision"
}
class customTap: UITapGestureRecognizer {
var cutomTag: String?
}
Use it, making sure you set the custom variable into the bargin. Using a simple label here, note the last line, important labels are not normally interactive.
let precisionTap = customTap(target: self, action: #selector(VC.actionB(sender:)))
precisionTap.customTag = Vs.precision.rawValue
precisionLabel.addGestureRecognizer(precisionTap)
precisionLabel.isUserInteractionEnabled = true
And setup the action using it, note I wanted to use the pure enum, but it isn't supported by Objective C, so we go with a basic type, String in this case.
#objc func actionB(sender: Any) {
// important to cast your sender to your cuatom class so you can extract your special setting.
let tag = customTag as? customTap
switch tag?.sender {
case Vs.pulse.rawValue:
// code
case Vs.precision.rawValue:
// code
default:
break
}
}
And there you have it.
cell.btn.tag = indexPath.row //setting tag
cell.btn.addTarget(self, action: #selector(showAlert(_ :)), for: .touchUpInside)
#objc func showAlert(_ sender: UIButton){
print("sender.tag is : \(sender.tag)")// getting tag's value
}
Just create a custom class of UITapGestureRecognizer =>
import UIKit
class OtherUserProfileTapGestureRecognizer: UITapGestureRecognizer {
let userModel: OtherUserModel
init(target: AnyObject, action: Selector, userModel: OtherUserModel) {
self.userModel = userModel
super.init(target: target, action: action)
}
}
And then create UIImageView extension =>
import UIKit
extension UIImageView {
func gotoOtherUserProfile(otherUserModel: OtherUserModel) {
isUserInteractionEnabled = true
let gestureRecognizer = OtherUserProfileTapGestureRecognizer(target: self, action: #selector(self.didTapOtherUserImage(_:)), otherUserModel: otherUserModel)
addGestureRecognizer(gestureRecognizer)
}
#objc internal func didTapOtherUserImage(_ recognizer: OtherUserProfileTapGestureRecognizer) {
Router.shared.gotoOtherUserProfile(otherUserModel: recognizer.otherUserModel)
}
}
Now use it like =>
self.userImageView.gotoOtherUserProfile(otherUserModel: OtherUserModel)
You can use an UIAction instead:
self.imageView.addAction(UIAction(identifier: UIAction.Identifier("imageClick")) { [weak self] action in
self?.handleTap(modelObj)
}, for: .touchUpInside)
that may be a terrible practice but I simply add whatever I want to restore to
button.restorationIdentifier = urlString
and
#objc func openRelatedFact(_ sender: Any) {
if let button = sender as? UIButton, let stringURL = factButton.restorationIdentifier, let url = URL(string: stringURL) {
if UIApplication.shared.canOpenURL(url) {
UIApplication.shared.open(url, options: [:])
}
}
}
There are a couple of existing questions on this topic but they aren't quite what I'm after. I've written a little Swift app rating prompt for my app which presents two UIAlertController instances, one triggered by the other.
I'm now trying to unit test this, and trying to reach that second alert in the tests. I've written a simple spy to check the first controller, but I'd like a way to trigger one of the actions on the first alert, which in turn shows the second.
I've already tried alert.actions.first?.accessibilityActivate(), but it didn't seem to break inside the handler of that action – that's what I'm after.
A solution that doesn't involve changing the production code to allow programmatic tapping of UIAlertActions in unit tests, which I found in this SO answer.
Posting it here as well as this question popped up for me when Googling for an answer, and the following solution took me way more time to find.
Put below extension in your test target:
extension UIAlertController {
typealias AlertHandler = #convention(block) (UIAlertAction) -> Void
func tapButton(atIndex index: Int) {
guard let block = actions[index].value(forKey: "handler") else { return }
let handler = unsafeBitCast(block as AnyObject, to: AlertHandler.self)
handler(actions[index])
}
}
Here's roughly what I did:
Created a mocked version of my class that would present the alert controller, and in my unit tests, used this mock.
Overrode the following method that I'd created in the non-mocked version:
func alertActionWithTitle(title: String?, style: UIAlertActionStyle, handler: Handler) -> UIAlertAction
In the overridden implementation, stored all the details about the actions in some properties (Handler is just a typealias'd () -> (UIAlertAction))
var didCreateAlert = false
var createdTitles: [String?] = []
var createdStyles: [UIAlertActionStyle?] = []
var createdHandlers: [Handler?] = []
var createdActions: [UIAlertAction?] = []
Then, when running my tests, to traverse the path through the alerts, I implemented a callHandlerAtIndex method to iterate through my handlers and execute the right one.
This means that my tests look something like this:
feedback.start()
feedback.callHandlerAtIndex(1) // First alert, second action
feedback.callHandlerAtIndex(2) // Second alert, third action
XCTAssertTrue(mockMailer.didCallMail)
I took a slightly different approach based on a tactic I took for testing UIContextualAction—it's very similar to UIAction but exposes its handler as a property (not sure why Apple wouldn't have done the same for UIAction). I injected an alert actions provider (encapsulated by a protocol) into my view controller. In production code, the former just vends the actions. In unit tests, I use a subclass of this provider which stores the action and the handler in two dictionaries—these can be queried and then triggered in tests.
typealias UIAlertActionHandler = (UIAlertAction) -> Void
protocol UIAlertActionProviderType {
func makeAlertAction(type: UIAlertActionProvider.ActionTitle, handler: UIAlertActionHandler?) -> UIAlertAction
}
Concrete object (has typed titles for easy retrieval later):
class UIAlertActionProvider: UIAlertActionProviderType {
enum ActionTitle: String {
case proceed = "Proceed"
case cancel = "Cancel"
}
func makeAlertAction(title: ActionTitle, handler: UIAlertActionHandler?) -> UIAlertAction {
let style: UIAlertAction.Style
switch title {
case .proceed: style = .destructive
case .cancel: style = .cancel
}
return UIAlertAction(title: title.rawValue, style: style, handler: handler)
}
}
Unit testing subclass (stores actions and handlers keyed by ActionTitle enum):
class MockUIAlertActionProvider: UIAlertActionProvider {
var handlers: [ActionTitle: UIAlertActionHandler] = [:]
var actions: [ActionTitle: UIAlertAction] = [:]
override func makeAlertAction(title: ActionTitle, handler: UIAlertActionHandler?) -> UIAlertAction {
handlers[title] = handler
let action = super.makeAlertAction(title: title, handler: handler)
actions[title] = action
return action
}
}
Extension on UIAlertAction to enable typed action title lookup in tests:
extension UIAlertAction {
var typedTitle: UIAlertActionProvider.ActionTitle? {
guard let title = title else { return nil }
return UIAlertActionProvider.ActionTitle(rawValue: title)
}
}
Sample test demonstrating usage:
func testDeleteHandlerActionSideEffectTakesPlace() throws {
let alertActionProvider = MockUIAlertActionProvider()
let sut = MyViewController(alertActionProvider: alertActionProvider)
// Do whatever you need to do to get alert presented, then retrieve action and handler
let action = try XCTUnwrap(alertActionProvider.actions[.proceed])
let handler = try XCTUnwrap(alertActionProvider.handlers[.proceed])
handler(action)
// Assert whatever side effects are triggered in your code by triggering handler
}
I used Luke's guidance above to create a subclass of UIAlertAction that saves its completion block so it can be called during tests:
class BSAlertAction: UIAlertAction {
var completionHandler: ((UIAlertAction) -> Swift.Void)?
class func handlerSavingAlertAction(title: String?,
style: UIAlertActionStyle,
completionHandler: #escaping ((UIAlertAction) -> Swift.Void)) -> BSAlertAction {
let alertAction = self.init(title: title, style: style, handler: completionHandler)
alertAction.completionHandler = completionHandler
return alertAction
}
}
You could customize this to save more information (like the title and the style) if you like. Here's an example of an XCTest that then uses this implementation:
func testThatMyMethodGetsCalled() {
if let alert = self.viewController?.presentedViewController as? UIAlertController,
let action = alert.actions[0] as? BSAlertAction,
let handler = action.completionHandler {
handler(action)
let calledMyMethod = self.presenter?.callTrace.contains(.myMethod) ?? false
XCTAssertTrue(calledMyMethod)
} else {
XCTFail("Got wrong kind of alert when verifying that my method got called“)
}
}