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iOS Enumerations and Optionals in Swift Introduction to Enumerations Enum Methods

Adam Petritsis
Adam Petritsis
2,942 Points
Posted by Adam Petritsis
Adam Petritsis
2,942 Points

How can you solve the last exercise in the Enumerations course for Swift 3?

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)    

}

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

1 Answer

David Papandrew
David Papandrew
8,386 Points
David Papandrew
David Papandrew
8,386 Points

Here are the steps:

1) Create an enum method called button() that returns a UIBarButtonItem

2) Inside the function body, create a switch statement that checks for the type of BarButton (done or edit)

3) For each case in the switch statement, return the appropriate UIBarButtonItem

Here's what that code would look like:

// 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: return UIBarButtonItem(title: "Done", style: .done, target: nil, action: nil)
        case .edit: return UIBarButtonItem(title: "Edit", style: .plain, target: nil, action: nil)
      }
    }
}

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