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Devin Boddie
6,777 PointsSwift 3 enum challenge part 2 of 2 Help needed
Below is the full question for the challenge, however i'm just not understanding what the second half of the challenge question is asking for. Any help would be appreciated.
Thank you
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.
// 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(title: "A Title", style: .plain, target: nil, action: nil) {
return BarButton.done()
}
}
let done = BarButton.done(title: "Save")
1 Answer
Dhanish Gajjar
20,185 PointsI would suggest going back and seeing the previous video again, where Pasan explains how to create a ColorComponent enum, with a single method called color, that switches on itself for both enum cases.
Similarly, you need to provide a single method called button() that returns a UIBarButtonItem for both enum cases.
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()
Devin Boddie
6,777 PointsDevin Boddie
6,777 PointsThank you!
This helped explain a lot.
kelake
4,223 Pointskelake
4,223 PointsWhy do we make local constants? I mean I can just follow his pattern and I get the right answer but I don't why we do it this way.
kols
27,007 Pointskols
27,007 PointsTo answer kelake's question ::
We do this — declare a local constant, e.g.,
so that we can reference it (in this case, passing it's value through for the title).
.done(let title)orlet .done(title)— because in order to use an enum member's associated value in the switch statement, you must extract it by creating a local constant to work with. We want to be able to pass this value through and utilize it in the return statement, so first we must name it ("Bastian, please; save us!")For more, check out the Swift documentation on Enums, particularly the Associated Values section.