How Do I Display A List Of Values From An Array Of A Customer Type From Struct [Swift]

Question

In ContentView: View I have an array of days with some data attached to it from HealthKit. The day is unique. The array is printing fine and everything to do that with that is correctly populated.

//Prep workouts to display
public struct workoutHistory {
    var workoutDate: Date
    var strengthCount: Int
    var cardioCount: Int
    var flexibilityCount: Int
}

@State public var workoutHistoryByDay: [workoutHistory] = []

Then in the body I try to display every date in a list (just to test at the moment)

ForEach(workoutHistoryByDay) { workoutDay in
    Text("\(workoutDay.workoutDate)")
    Text("\(workoutDay.strengthCount)")
}

When I do this I get the error:

Referencing initializer 'init(_:content:)' on 'ForEach' requires that 'ContentView.workoutHistory' conform to 'Identifiable'

I have tried updating my struct to include : Identifiable and I get the error

Type 'ContentView.workoutHistory' does not conform to protocol 'Identifiable'

I have also tried updating the ForEach to include ID

ForEach(workoutHistoryByDay, id: .workoutDate) { workoutDay in
    Text("\(workoutDay.workoutDate)")
    Text("\(workoutDay.strengthCount)")
}

And I get the error

Generic parameter 'ID' could not be inferred

My question is, how to I properly list every .workoutDate and .strengthCount in my array workoutHistoryByDay ? Thank you.

Answer 1

try this approach, as in this sample code, works very well for me:

struct ContentView: View {
    // -- here some test workout
    @State public var workoutHistory: [Workout] = [
        Workout(workoutDate: Date(), strengthCount: 1, cardioCount: 2, flexibilityCount: 3),
        Workout(workoutDate: Date(timeIntervalSinceNow: Double(86400 * 1)), strengthCount: 2, cardioCount: 2, flexibilityCount: 3),
        Workout(workoutDate: Date(timeIntervalSinceNow: Double(86400 * 2)), strengthCount: 3, cardioCount: 2, flexibilityCount: 3)]
    
    var body: some View {
        List {
            ForEach(workoutHistory) { workout in
                Text("\(workout.workoutDate)")
                Text("\(workout.strengthCount)")
            }
        }
    }
}


public struct Workout: Identifiable {  // <-- here
    public let id = UUID() // <-- here
    var workoutDate: Date
    var strengthCount: Int
    var cardioCount: Int
    var flexibilityCount: Int
}

You would gain a lot by doing the tutorial again at: https://developer.apple.com/tutorials/swiftui/

Answer 2

You have to inherit Identifiable protocol to your struct model and need to confirm ID.

public struct workoutHistory: Identifiable {  //<== here
    public var id: Date { //<== here
        self.workoutDate
    }
    var workoutDate: Date
    var strengthCount: Int
    var cardioCount: Int
    var flexibilityCount: Int
}

you can return workoutDate as an id if the date is unique else you have to set a unique id.