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iOS Build a Vending Machine App in Swift 2.0 Displaying Additional Views Displaying an Alert View

When I click on the purchase button, I am receiving an NSInvalidArgumentException VendingMachine.ViewController purchase

'NSInvalidArgumentException', reason: '-[VendingMachine.ViewController purchase:]: unrecognized selector sent to instance 0x7f866be23e20'

My purchase function looks like this:

    @IBAction func purchase() {
        if let currentSelection = currentSelection {
            do {
                try vendingMachine.vend(currentSelection, quantity: quantity)
            } catch VendingMachineError.OutOfStock {
            } catch {

        } else {
            // FIXME: Alert user to no selection

1 Answer

Go to your Main.storyboard and right click the 'Purchase' button. Under 'sent events' make sure that Touch Up Inside isn't linked to your purchase function more than once. Delete the purchase function that has a colon. That worked for me.