How do I uninitialize a variable reference in Swift

Question

I have a @IBAction function that accepts a sender: UIButton! as a parameter.

@IBAction func buttonPress(sender: UIButton!)

At some point in the function, I am copying the sender to another variable which was previously declared as a UIButton()

anotherVar = sender

I understand this is a reference to the original sender given UIButton is a class

However at some point of the code, I want to break the reference to sender and "reset" anotherVar to a plain vanilla UIButton(). How would I do this?

EDIT: I feel I should expand on what I'm doing, perhaps I'm going about this the wrong way...

I have eight buttons all calling the same @IBAction function called buttonPress(). The idea is for the user to tap a button, see an image and then tap another button (out of the remaining seven) to find the matching image. When buttonPress() gets called, the code: 1. Checks to see if this is a first button being tapped - if it is, it shows the button image and then assigns sender to anotherVar; - if it is the second button being pressed (ie another button was previously clicked), the code runs a match to compare the sender's image to anotherVar's image which was set above 2. If there is a match, I "lock" the buttons so the matching logic doesn't get executed if the user taps the buttons again 3. If there is no match, I want to "clear out" anotherVar ready for another matching task. I don't want to "lock" the buttons as the same button may still need to be clicked.

Here's the full code:

@IBAction func buttonPress(sender: UIButton!) {

    var buttonImage = UIImage()
    buttonImage = UIImage(named: listOfImages[sender.tag])!

    if (!imageIsDone[sender.tag] && (sender.tag != buttonToCompare.tag)) {
        // Only execute button logic if match for image not already found and the user isn't tapping the same image
        if (imageAwaitingCheck) {
            // User has made their first image selection, do matching logic on image clicked
            sender.setImage(buttonImage, forState: .Normal)
            if (sender.currentImage == buttonToCompare.currentImage) {
                // Tapped image macthes previously clicked image
                println("Match")

                // "Lock" the buttons as they've been matched
                imageIsDone[sender.tag] = true
                imageIsDone[buttonToCompare.tag] = true
                imageAwaitingCheck = false  
            }
            else {
                // Tapped image does not match previously clicked image
                println("No match")
                imageAwaitingCheck = false
                buttonToCompare.tag = 100 
                // ********ERROR IS HERE*********I forced this so that
                // (sender.tag != buttonToCompare.tag) is true above when
                // the user taps on the first button again after no match is found.
                // However, this is a REFERENCE to the original sender and sets the
                // button tag to 100 which causes the condition to fail and hence
                // tapping button 1, then button 2, no match, then clicking button 1
                // again doesn't execute any of this logic
            }
        }
        else {
            // User has selected this as the first image, simply show it
            sender.setImage(buttonImage, forState: .Normal)
            imageAwaitingCheck = true
            buttonToCompare = sender // I am copying sender to buttonToCompare. Ideally this would create a copy but because UIButton is a class, this is creating a buttonToCompare as a reference
        }

    }

}

Answer 1

As long as anotherVar is assigned as var , not let , you can simply do the following when you're done with the sender :

anotherVar = UIButton()

This will "overwrite" the previous value of anotherVar and "reset" it to a new instance of UIButton .

However, you probably don't need to do this at all if the only place you're accessing anotherVar is this function - as long as you call anotherVar = sender , that will also replace the reference to the previous button with the new sender button.

---

To achieve what you describe after your edit, you don't really need to make a lot of changes. In this if-statement: if (sender.currentImage == buttonToCompare.currentImage) add buttonToCompare = UIButton() at the very end. In the else -statement, do the same instead of changing it's tag.

Alternatively, if you want the sender to be copied, you can do that like this:

let archivedData = NSKeyedArchiver.archivedDataWithRootObject(button)
let buttonCopy = NSKeyedUnarchiver.unarchiveObjectWithData(archivedData)