I'm trying to create a custom class that creates a button. I'm having trouble adding a target to that button inside it's class. This is my code
class SelectButton{
var button:UIButton = UIButton()
init(button_frame: CGRect, button_title: String, connected: [UIButton]?){
self.button.frame = button_frame
self.button.setTitle(button_title, for: UIControlState.normal)
self.button.addTarget(self, action:#selector(self.buttonPressed), for: .touchUpInside)
}
func construct() -> UIButton {
return self.button
}
#objc func buttonPressed() {
print("Button Clicked")
}
}
The problem is that I can't connect an action on button click. This works if it's used outside my class but not inside.
Usage of the class
let test = SelectButton(button_frame: CGRect(x:50, y:50, width: 250, height:150), button_title: "Test button", connected: nil).construct()
self.view.addSubview(test)
When someone taps the button, usually you want something to happen somewhere else in your app (like in one of your view controllers or in some other UI element). The way the IBAction is set up right now, you have it so that something will trigger or happen within the button itself when someone taps on it. If you want to handle a button tap programmatically instead of ctrl dragging from the button into the view controller, you can do it this way if you prefer. First, add this code into the view controller:
#IBAction func buttonPressed(sender: UIButton) {
}
Then you can either add the selector programmatically by adding this method into your view controller:
myButton.addTarget(self, action:self.buttonPressed(sender), for: .touchUpInside)
Or by going to the connections inspector and dragging from the touch up inside over to the IBAction dot in your view controller code. Also, as someone else pointed out in the comments you should make your button inherit from UIButton by adding this to your class declaration:
class SelectButton: UIButton {
. . .
}
Nothing is holding a strong reference to your SelectButton instance, so as soon as the function that creates test exits, that instance is released.
The button itself is retained because you have added it as a subview. Therefore, it is still visible but there is no longer an object to respond to the action.
You either need to use an instance property rather than a local variable for test, or, preferably have SelectButton inherit directly from UIButton
Related
We want Lyft button touch event because I am working in analytics, so, I need how many people choose Lyft but I can't put UIView click event. I try below code.
let gesture = UITapGestureRecognizer(target: self, action: #selector(self.checkAction))
cell.lyftButton.addGestureRecognizer(gesture)
How can i achieve this?
You can directly assign a selector method to lyftButton e.g
lyftButton.addTarget(self, action: #selector(lyftButtonAction(_:)), for: .touchUpInside)
#objc
func lyftButtonAction(_sender: UIButton) {
//Do your action
}
To retrieve the LyftButton, you'll need to fetch the button inside the Lyft view, after retrieving it, I tried to add another target to it which was your 'checkAction' method, but for some reason it is not being called. One workaround solution is:
On Auto Layout, created a transparent button on top of the Lyft Button View, let's callet it 'Transparent Lyft Button': Example (I've embeded in another view because it was on a stackView);
On the code, retrieved the button with the above method, held it in a variable, let's call it 'requestLyftButton' and disabled it.
Created an IBAction for the 'Transparent Lyft Button' that triggers the method 'self.checkAction' that you've created and also calls requestLyftButton.sendActions(for: .touchUpInside), which triggers the original Lyft SDK action.
To Retrieve Lyft UIButton:
#IBOutlet weak var lyftButton: LyftButton!
#IBOutlet weak var transparentLyftButton: UIButton!
var requestLyftButton: UIButton?
func retrieveLyftButton(in view: UIView) {
for view in view.subviews {
if let lyftBtn = view as? UIButton {
lyftBtn.isEnabled = false
requestLyftButton = lyftBtn
} else {
retrieveLyftBtn(in: view)
}
}
}
transparentLyftButton IBAction to trigger your method + lyft sdk original action:
#IBAction func requestLyft(_ sender: UIButton) {
if let lyftBtn = requestLyftButton {
checkAction() // Your method
lyftBtn.sendActions(for: .touchUpInside)
}
}
I hope that you can understand what was done, if you have any questions, just let me know.
I am trying to make my button, when tapped, to push to a new View Controller. I've tried many different ways but it won't trigger the function that I have it linked to. I also checked the 3D stack view of my layers and the button is on top and clickable, even when I check the background color, it's not being covered by anything else.
Does anyone have any ideas to what I am doing wrong?
For now I am trying to make the button print out the sentence in the console, however whenever I press it, the string doesn't pop up, so I haven't bothered to connect it to the view controller yet.
Also, I am coding this app without storyboards.
Here is my code below.
It is under the MainPageCell class declared as a UICollectionViewCell
private let playButton: UIButton = {
let button = UIButton()
button.setTitle("", for: .normal)
button.backgroundColor = .clear
button.translatesAutoresizingMaskIntoConstraints = false
button.addTarget(self, action: #selector(MainPageCell.buttonTapped), for: .touchUpInside)
return button
}()
#objc func buttonTapped() {
print("I PRESSED THE BUTTON")
}
This line is wrong:
button.addTarget(self, action: #selector(MainPageCell.buttonTapped), for: .touchUpInside)
You cannot assign self as the action target in a property declaration initializer, because the instance designated by self does not exist yet. There is no error or warning (I regard that as a bug), but the action method is never called.
Move that assignment elsewhere and rewrite it, like this:
self.playButton.addTarget(self, action: #selector(MainPageCell.buttonTapped), for: .touchUpInside)
Maybe try defining your button action under the UIView Class, I've had a problem like that before, only worked when i linked it to the View Class, Good luck
I have a custom UIControl that has three subviews. Each of those subviews, I add a target:
button.addTarget(self, action: #selector(buttonTapped(clickedBtn:)), for: .touchUpInside)
Within that function buttonTapped, it does some special animations to do some transitions (It mimics the segmented control).
Now, within the ViewController that this custom UIControl exists in must know when it's touched. I created an #IBAction function that interacts with the touch events for the custom UIControl.
The problem is, that isn't possible (as far as I know). If I add a target touch event to the subviews, the parent touch events won't get called. To have the parent view called the #IBAction function, I must set all the subview's setUserInteractiveEnabledtotrue`. When I do that, the subview's touch event functions won't get called.
I need both touch event functions to be called. How can I do this? Or what's the best way to get around this?
Use delegates, add a protocol in your UIControl that needs to be implemented in your ViewController.
This way you can detect if a button is clicked in your UIControl and invoke a specific function in your VC.
For Example:
//YourUIControl.Swift
protocol YourUIControlDelegate {
func didTapFirstButton()
}
class YourUiControl : UIView { //I'm assuming you create your UIControl from UIView
var delegate : YourUIControlDelegate?
//other codes here
.
.
.
#IBAction func tapFirstButton(_ sender: AnyObject) {
if let d = self.delegate {
d.didTapFirstButton()
}
}
}
//YourViewController.Swift
extension YourViewController : UIControlDelegate {
func didTapFirstButton() {
//handle first button tap here
}
}
I try figure out why self point to the GameViewController instead of Answer
GameViewController.swift
class GameViewController: UIViewController {
var gameplay = QuestionsController(colors: colors)
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(gameplay.answersController.answers[0].button)
}
func didPressAnswerButton(sender: UIButton!) {
sender.setTitle("Im from GameViewController class", forState: .Normal)
}
}
QuestionsController.swift
class QuestionsController {
var question: Question
var answersController: AnswersController
}
AnswersController.swift
class AnswersController {
var answers = [Answer]()
func prepareAnswers() {
let answer = Answer()
answers.append(answer)
}
}
Answer.swift
class Answer{
let button: UIButton
func prepareButton() {
let answerButton = AnswerButton(type: .System)
answerButton.addTarget(self, action: "didPressAnswerButton:", forControlEvents: .TouchUpInside)
button = answerButton
}
func didPressAnswerButton(sender: UIButton!) {
sender.setTitle("Im from Answer class", forState: .Normal)
}
}
addTarget:action:forControlEvents: tells the control (answerButton in this case) what method to call, and what object to call it on, when the user taps the button. Looking at your code in more detail:
answerButton.addTarget(self, action: "didPressAnswerButton:", forControlEvents: .TouchUpInside)
When the user taps a button, the TouchUpInside event fires on the answerButton, and when that happens we want to invoke a method didPressAnswerButton: on an Answer object
So, we need to tell answerButton what do do when this TouchUpEvent fires. You do this calling the addTarget:action:forControlEvents method on the answerButton
The self argument tells the answerButton what object to notify about the event: it is the target. In this context, self is an Answer object.
The "didPressAnswerButton:" argument indicates what method the answerButton should call in response to the tap event: this is the action
This is the target-action mechanism of Objective-C/Cocoa. It's a very common pattern, it's worth it to read the linked documentation to learn a bit more about how it works. The key is that this is based on Objective-C* message passing: in the code above, "didPressAnswerButton:" indicates a selector, which when paired with a target (self), tells the answerButton how to send a "message" to the target when the user taps the button.
Also, note that when you are editing a storyboard and ctrl-drag from a button to your view controller and select a method, you are also setting up a target/action using this same mechanism. You select the target object by dragging to the view controller icon (or some other icon), and then you pick the action/selector when clicking on a method name in the popup.
* Target-Action was originally designed for Objective-C, but for the common case of implementing a view controller, you can assume Swift works the same way. Just note when reading documentation that Swift uses simple strings for actions, whereas Objective-C uses #selector(...).
Normally you can link a slider to an #IBAction using the storyboard, then anytime the slider is moved, that method is executed, but...
Let's say I have a slider inside a tableViewCell. Normally I can only access it by tag because it isn't the same slider as the one on the StoryBoard:
let slider = cell.viewWithTag(1000) as UISlider
And change or access it like this:
slider.value = lroundf(50)
But what if I want to link it to an #IBAction? What if I want it to do something when the slider is moved? How would I do this if it's inside a cell?
I noticed that there's a method called "didChange", but there is absolutely no documentation anywhere on how to use this method or if it does what it is I'm trying to do.
slider.addTarget(self, action: "sliderMoved:", forControlEvents: .ValueChanged)
func sliderMoved(slider: UISlider) {
println("value: \(slider.value)")
}