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iOS Enumerations and Optionals in Swift Introduction to Enumerations Enum Methods

Posted by mitchellwan
mitchellwan
3,620 Points

Why does my code not work here?

Next, add a method to the enum named button that returns an instance of the class UIBarButtonItem configured properly. An example of how to create an instance for this task is shown in the comments below. Use the same initializer.

In the method, using the associated values as titles for the button, return a button with style UIBarButtonStyle.done for the done member of the BarButton enum. Similarly for the edit member, return a UIBarButtonItem instance with the style set to UIBarButtonStyle.plain.

In both cases you can pass nil for target and action. Once you have a method, call it on the value we created in the previous task and assign it to a constant named button.

buttons.swift 
// Example of UIBarButtonItem instance
// let someButton = UIBarButtonItem(title: "A Title", style: .plain, target: nil, action: nil)

enum BarButton {
    case done(title: String)
    case edit(title: String)

  func button() -> UIBarButtonItem {
    switch self {
      case .done(let title, let style, let target, let action): 
        return UIBarButtonItem(title: title, style: .done, target: nil, action: nil) 
      case .edit(let title, let style, let target, let action): 
        return UIBarButtonItem(title: title, style: .plain, target: nil, action: nil) 

    }
  }
}

let done = BarButton.done(title: "Save") 
let button = done.button()
Victor Mercier
Victor Mercier
14,667 Points

Hi, here is a more detailed answer about why your code was not working.

At this line of code, you are assigning the .done member (in the enum method) some constants that do not match the associated values you declare earlier in the done member. 

.done(let title, let style, let target, let action)

Hope this is clearer!

1 Answer

Victor Mercier
Victor Mercier
14,667 Points

Hi, here is my code:

enum BarButton {
    case done(title: String)
    case edit(title: String)

    func button() -> UIBarButtonItem {
     switch self {
     case .done(let title): return UIBarButtonItem(title: title, style: .done, target: nil, action: nil)
     case .edit(let title): return UIBarButtonItem(title: title, style: .plain, target: nil, action: nil)
      }
    }
}

let done = BarButton.done(title: "Save")
let button = done.button()

The main thing you are doing wrong is that you cannot assign enum associated that don't exist in your enum in the enum method. If that helped you, please mark as best answer to indicate other students your issue is resolved!

mitchellwan
mitchellwan
3,620 Points

I see now, thank you!