How to use one IBAction for multiple buttons in Swift? - ios

Question

I have multiple buttons each one with the ability to switch the language of the app. Instead of having to create multiple IBActions for each button is there a way to have them all connected to one IBAction and change the language based on the button pressed? I'm thinking a switch statement would be good to use in this situation but not exactly sure how to set it up.

Answer 1

In Interface Builder, select the Attributes Inspector and set the Tag for each button with a unique number, then you can do something like this:
#IBAction changeLanguage(sender: AnyObject) {
guard let button = sender as? UIButton else {
return
}
switch button.tag {
case 1:
// Change to English
case 2:
// Change to Spanish
case 3:
// Change to French, etc
default:
print("Unknown language")
return
}
}
To connect the action to multiple buttons: in Interface Builder, right-click ViewController in the view hierarchy, then left-click to drag the action connection to each button.

Answer 2

Yes, a switch statement is the way to go here. For a UIButton, you link it to a selector that is called when the user interacts with the button, generally the TouchUpInside event. The addTarget method, and valid selector signatures (apple.com) Of these, you want to use a method in the format #IBAction func doSomething(sender: UIButton) or #IBAction func doSomething(sender: UIButton, forEvent event: UIEvent), so that a reference to the button that triggered the event is passed to the selector.
In your ViewController code, you'll have references to your UIButtons (possibly in a storyboard, or created manually.) Let's say you have
#IBOutlet weak var frenchButton: UIButton!
#IBOutlet weak var spanishButton: UIButton!
#IBOutlet weak var englishButton: UIButton!
You would connect all of them to the same method, and branch the logic based on which one was the sender. e.g.:
#IBAction func changeLanguage(sender: UIButton) {
switch sender {
case frenchButton:
// Change Language to French
print ("C'est si bon")
case spanishButton:
// or Spanish
print ("Muy Bueno")
case englishButton:
// or English
print ("It's pretty cool")
default:
break
}
}
Note: Case statements in Swift must be exhaustive, so you have to include a default case, even though it should never be called.

Answer 3

Do not set tag if you have reference to the button.
You can just compare the reference instead of tags. This way, you won't introduce a new bug, because unlike a tag that you type yourself, reference is created by compiler automatically.
#IBOutlet weak var firstButton: UIButton!
#IBOutlet weak var secondButton: UIButton!
#IBOutlet weak var thirdButton: UIButton!
#IBAction changeLanguage(sender: UIButton) {
if sender == firstButton {
} else if sender == secondButton {
} else if sender == thirdButton {
}
}