Executing a function when a view appears - Swift

Question

I'm building an app for iOS using the Swift language. I start with a table view controller as my root view controller, and then I have a secondary view controller in which a variable (passData) is defined. This all works fine, and it passes the data correctly (I think) from the secondary view controller back to the primary view controller. However, when the user returns back to the primary view controller, I need a function to execute which will then add the 'addTitle' value to an array. I know how to add it to the array, but...

I don't know how to initiate the function when the view is returned to. What I mean is, after the user is finished on the secondary view controller AND the variable "passData" is defined, they will then push the back button on the navigation bar. I then need the primary view controller to recognise that it is once again being displayed to the user, and then execute the following code:

tableData += [passData]
tableSubtitle += [passDescription]

I have tried the following:

override func viewDidAppear() {
    tableData += [passData]
    tableSubtitle += [passDescription]
}

But this gives the error as Method does not override any method from its superclass.

Essentially, I just need to know how to start a function when the view displays. How can i achieve this?

Answer 1

you need to call super.viewDidAppear(animated) and the method signature takes a Bool so you should say:

override func viewDidAppear(animated: Bool)

ProTip: If you want to override a method you can just start typing the method name you want to overload and Xcode will auto suggest the method name and fill in the override declarative. So on a new line start typing viewDid and you should see the viewDidAppear method in the autocompletion drop down. Pressing enter will complete the method signature for you.