These two items (the SwiftUI Picker and a Swift enum) work really well together. Some might say they go together as well as Peanut Butter and Banana.
Requirement: Your app needs a way for a user to choose how to sort their list items. Today list items can be sorted by Name, Height and Average Score. Some time in the future, the list of sort types is expected to grow.
Eventually we are going to need some UI for this, but let’s start be defining an enum to define the sort types. Our enum needs to conform to CaseIterable because we will need to call the allCases class method. I don’t think String is required, but is helpful in the initial stage before we polish the UI.
enum SortType: String, CaseIterable {
case name
case height
case averageScore
}And also a Settings model object to store our source of truth (ie sort type) We will access the Settings singleton via the shared static variable. Settings needs to conform to ObservableObject because the Picker will bind to the sortType property.
class Settings: ObservableObject {
static let shared = Settings()
@Published var sortType: SortType
init() {
sortType = .name
}
}For the UI, we will use the following Picker init
public init(selection: Binding<SelectionValue>, label: Label, @ViewBuilder content: () -> Content)The UI content view will start with something like this:
struct ContentView: View {
@ObservedObject var settings = Settings.shared
var body: some View {
VStack {
Picker(selection: $settings.sortType, label: Text("Sort Type")) {
ForEach(SortType.allCases, id: \.self) { sortType in
Text("\(sortType.rawValue)")
}
}
Text("sort type is: \(settings.sortType.rawValue)")
}
}
}If we run this code, we’ll see a picker above a text label. When we pick a different value in the picker, the text label updates accordingly. Woot!
In Part 2, we will:
- Improve the UI by adding display names for the sort types
- Use UserDefaults to persist and recall the selected sort type
- Add another sort type
