Ok so I want to be able to disable the button within itself. So when I press the button it will disable itself.
import UIKit
class ViewController: UIViewController {
#IBOutlet var buttons: [UIButton]!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
#IBAction func but(_ sender: AnyObject) {
//this code doesn't seem to work at all, and I don't know why
(sender as AnyObject).isEnabled = false
}
}
It gives me an error message when ever I try to do this "Cannot assign to immutable expression of type '#lvalue Bool?'"
So is there a different way I can disable this button
Presumably, you've hooked up this IBAction in Interface Builder to a UIButton. So, you can change your function signature to:
#IBAction func but(_ sender: UIButton) {
sender.isEnabled = false
}
AnyObject doesn't have a property called isEnabled, which is why your previous code failed.
within the button I use this code
#IBAction func but(_ sender: AnyObject) {
var disableMyButton = sender as? UIButton
disableMyButton?.isEnabled = false
}
Related
Quite new to programming in Swift and mobile development in general. I am trying to use performSegue() and control it without if-else statements. I made a google search how to use override func shouldPerformSegue() and tried to implement it in different ways but none of them solved my situation. Here I need to segue to Yellow or Green views if the switch is on using corresponding buttons. Even if I made return false, the function does not cancel the segue to happen. What is the reason of this behaviour and how can I fix it? Many thanks.
class ViewController: UIViewController {
#IBOutlet var segueSwitch: UISwitch!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
#IBAction func yellowButtonTapped(_ button: UIButton) {
performSegue(withIdentifier: "Yellow", sender: nil)
}
#IBAction func greenButtonTapped(_ button: UIButton) {
performSegue(withIdentifier: "Green", sender: nil)
}
override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
// return segueSwitch.isOn
return false
}
}
shouldPerformSegue does not get called if you use performSegue(withIdentifier: in code. This function only get called if the segue is triggered from storyboard.
You can easily test this by adding 2 Buttons to a ViewController in storyboard one with the storyboard segue and one with an IBOutlet to a new ViewController. Then add a print statement to shouldPerformSegue. In the Button outlet call performSegue. Only the first button performing the segue from storyboard will print to the console.
And additionally you don´t need it. Any validation you would perform in shouldPerformSegue can be done in the ...ButtonTapped function:
#IBAction func yellowButtonTapped(_ button: UIButton) {
if validateSegue(){
performSegue(withIdentifier: "Yellow", sender: nil)
}
}
override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
validateSegue()
}
func validateSegue() -> Bool{
......
}
This is deliberate and makes perfect sense. shouldPerformSegue lets you prevent an automatically triggered segue in case you don't want it performed. But if you didn't want a manual segue performed, all you had to do is nothing — don't say performSegue in the first place.
and control it without if-else statements
If-else is exactly how to control it.
my problem looks so simple, but since I am a beginner, I have problem to understand the concept of the closure to pass data between two controllers
for example I have a static table view controllers that has one cell and a title inside it
class FirstView: UITableViewController {
#IBOutlet weak var titleLabel: UILabel!
and I have an another view controller that contain a button inside it
class SecondViewController: UIViewController {
#IBAction func pressChangeButton(_ sender: UIButton) {
}
and there is segue1 between these two controllers, with identifier "segue1"
I want a to a simple task, I want to add a boolean closure that it will be true if the change button is pressed.
that is why I create a closure function the second view controller that has change button.
var change : ((Bool) -> Void)?
I just want, that the second view controllers tells the first one that change closure is now true (after pressing the change button) and the first view controllers simply change the title table inside it to whatever (I just want to see that how it can be done)
I don't know I have to use prepare sugue function?
Could anyone help me to understand this concept?
You can try
class FirstView: UITableViewController {
#IBOutlet weak var titleLabel: UILabel!
#IBAction func goToSecond(_ sender: UIButton) {
self.performSegue(withIdentifier: "segue1", sender: nil)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "segue1" {
let des = segue.destination as! SecondViewController
des.change = { [weak self] (value) in
print(value)
self?.titleLabel.text = "SetValue"// set a value
}
}
}
}
class SecondViewController: UIViewController {
var change : ((Bool) -> Void)?
#IBAction func pressChangeButton(_ sender: UIButton) {
change?(true)
}
}
A closure is basically a piece of code that you can run. In Swift a closure is a first class citizen as it can be passed around as parameters and return type of functions. That being said, you can pass or set a closure as you normally would for other objects.
As per Sh_Kan's answer, just set SecondViewController's closure in prepare(for segue:sender:), always paying extra attention to retain cycles. You might also want to take a look at delegate design pattern in order to exchange data and messages between your controllers.
I am using SWRevealViewController for side menu. while i click on menuBtn, im performing right toggle operation. I want the same when i swipe right Can any one Please Help me with it.
class Invoice: UIViewController {
#IBOutlet weak var menuBtn: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
let revealViewController = self.revealViewController()
menuBtn.addTarget(revealViewController, action: #selector(SWRevealViewController.rightRevealToggle(_:)), for: .touchUpInside)
}
#IBAction func swipeGesture(_ sender: UISwipeGestureRecognizer) {
print("Swiped")
//I want same action as i clicked on mentBtn
}
}
Something like this should work:
#IBAction func swipeGesture(_ sender: UISwipeGestureRecognizer) {
self.revealViewController().rightRevealToggle(self.menuBtn)
}
Struggling to get my viewControllers to send value from the main viewController to a second. I want it to happen on a button click, I'm going to get the value from the button and pass it to the new form. But it just isn't working.
Code for main ViewController
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func butClick(_ sender: UIButton) {
NSLog("Button Pressed : %#",[sender .currentTitle])
//var tt = [sender .currentTitle]
// Create the view controller
let vc = TimesTablesViewController(nibName: "TimesTablesViewController", bundle: nil)
vc.passedValue = "xx"
self.performSegue(withIdentifier: "pushSegue", sender: nil)
}
}
Code for second viewController called TimesTablesViewController:
class TimesTablesViewController: UIViewController {
#IBOutlet weak var titleLabel: UILabel!
var passedValue:String = ""
override func viewDidLoad() {
super.viewDidLoad()
titleLabel?.text = "\(passedValue) Times Table"
}
}
I've followed tutorials but can't seem to solve the problem! Thanks for any help!
Replace
self.performSegue(withIdentifier: "pushSegue", sender: nil)
with
self.present(vc,animated:true,completion:nil)
or ( if the current vc is inside a naigation )
self.navigationController?.pushViewController(vc,animated:true)
Using
self.performSegue(withIdentifier: "pushSegue", sender: nil)
is fit with storyboards not xibs and if this your case then you need to use the above line only inside the button action with implementing this method inside the source vc
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "pushSegue" {
if let nextViewController = segue.destination as? TimesTablesViewController{
nextViewController.passedValue = "xx"
}
}
}
I’m assuming that the new view controller is appearing, but you’re simply not seeing the data. If so, you’re evidently using storyboards. The TimesTablesViewController(nibName:bundle:) only works if you’re using XIB/NIBs and manually presenting new view controller.
If you’re really using storyboards, simplify your butClick method:
#IBAction func butClick(_ sender: UIButton) {
NSLog("Button Pressed")
performSegue(withIdentifier: "pushSegue", sender: self)
}
But implement prepare(for:sender:):
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destination = segue.destination as? TimesTablesViewController {
destination.passedValue = "xx"
}
}
Assuming the above fixes your problem, I might suggest a further simplification. Notably, if your butClick(_:) method is really only calling performSegue, you can segue to this next scene without any #IBAction method at all:
remove butClick(_:) entirely;
remove the connection between the button and the butClick method in IB, on the “Connections Inspector” tab in the right panel; and
control-drag from the button previously hooked up to butClick(_:) to the scene for TimesTablesViewController.
That will simplify your code further.
I try to make a button invisible after pressing it. The Connection is an action and not an outlet, because pressing the button will call additional code.
#IBAction func startGame(_ sender: Any) {
print("The game starts...")
}
This does not work, because the button is an action and not an outlet:
startGame.isHidden = true
Is there another way to make an action button invisible and therefore not clickable?
Just create an IBOutlet of the same button and set its isHidden property to true once it's tapped.
#IBAction func startGame(_ sender: Any) {
startGameButton.isHidden = true
}
You can hide button on pressed action this way
#IBAction func startGame(_ sender: Any) {
let pressedButton : UIButton = sender as! UIButton
pressedButton.isHidden = true;
}
You can rewrite your code a little bit as Pratik suggested, so it will look like this:
#IBAction func startGame(_ sender: UIButton) {
sender.isHidden = true
/*
remove button at all from the parent view.
sender.removeFromSuperview()
*/
print("The game starts...")
}