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iOS

Posted by Anton Grishchenko
Anton Grishchenko
3,026 Points

Access button from another view controller

Let's say I have a firstViewController and a secondViewController. The first one contains a firstButton and the second one - a secondButton. Here's what I want to do: when user clicks the secondButton, some firstButton's property changes.

Unfortunately, when I create an instance of a firstViewController in a secondViewController and then trying to access a firstButton, I get an error:

"fatal error: unexpectedly found nil while unwrapping an Optional value (lldb)"

So, technically, I'm trying to do this as follows:

var ins = firstViewController()

@IBAction func secondButtonisPressed(){ ins.firstButton.alpha = 0 }

What is the proper way to implement that?

Thanks in advance.

1 Answer

Tatiana Jamison
Tatiana Jamison
6,188 Points
Tatiana Jamison
Tatiana Jamison
6,188 Points

Hey Anton! One design pattern to accomplish this is with custom delegation. You can read about it in the Apple documentation here or see an example on StackOverflow (under Passing Data Back, on the first response). Unfortunately, it's not something you can implement with a single line of code, but it is a really powerful design pattern that you will see over and over again as you continue iOS development! (Please feel free to ask follow-up questions if you want help implementing it for your project!)