update label on parent view from child view with Swift and delegates

Question

I am trying to update a label in my parent view (JL1EX3.swift) based on a buttonPressed event from my child view (inputPopUp.swift). I am aware I need to implement delegates/protocols for this to happen but am clueless as how to do so. Here's the code within my child view:

weak var parentView: JL1EX3!
var char: String!
var buttonPressed = String()

//Setter 
func setChar(var thisChar: String){
    char = thisChar
}

//Getter
func getChar()-> String{
    if (buttonPressed == "addButton"){
        char = "+"
    }
    if (buttonPressed == "minusButton"){
        char = "-"
    }
    if (buttonPressed == "divideButton"){
        char = "/"
    }
    if (buttonPressed == "multiplyButton"){
        char = "*"
    }
    println(char)
    return char
}


@IBAction func addButtonPressed(sender: AnyObject) {
    buttonPressed = "addButton"
    setChar("+")
    getChar()
    self.parentView.tapLabel.text = getChar() //Does not work - returns nil
    self.removeAnimate()
}

Your help would be very much appreciated!!

I thought I assigned it on the first line, no? weak var parentView: JL1EX3! — Gavin Friel
– Gavin Friel, Commented Aug 19, 2015 at 20:53

Andriy Gordiychuk · Accepted Answer · 2015-08-19 21:34:37Z

0

weak var parentView: JL1EX3!

does not assign a parent view. All this line does is declares a variable which is of class JL1EX3. It doesn't create any references to any particular instance of class JL1EX3.

Firstly, I strongly discourage you from using implicit unwrapping. Better declare your parent view like

weak var parentView: JL1EX3?

Secondly, ensure that you assign the parentView variable. You should do this after you initialise your inputPopUp.

For example:

let myPopUp = inputPopUp()
myPopUp.parentView = self //this assigns the parentView. Otherwise it is nil

I hope this helps

answered Aug 19, 2015 at 21:34

Andriy Gordiychuk

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