Multilevel Array Appending

You add an exercise to a plan.

So, in addExercise, you should add a plan reference:

func addExercise(forPlan: Plan)

and then

forPlan.insert() // What you need to insert

I was not precise enough. Correction is straightforward.

forPlan.exercise.insert() // What you need to insert

Note: you'd better name it exercises and not exercise.

    @Published var plans: [Plan] = []
    
    func addPlan(_ item: String) {
        let plan = Plan(name: item, exercises: [])
        plans.insert(plan, at: 0)
    }
    
    func addExercise(to planIndex: Int, exercise: Exercise) {
        guard planIndex >= 0 && planIndex < plans.count else {
            return 
        }
        
        plans[planIndex].exercises.append(exercise) 
    }
}

check this...

What JaiRajput said, plus.

When you add an exercise, you give it a name.

So code should be:

final class ViewModel: ObservableObject {
    @Published var plans: [Plan] = []
    
    func addPlan(_ item: String) {
        let plan = Plan(name: item, exercise: [])
        plans.insert(plan, at: 0)
    }

    func addExercise(to planIndex: Int, exoName: String) {
        if exoName == ""  { return }
        if planIndex < 0 || planIndex >= plans.count { return }

        // Also test exoName does not exist there already
        for exo in plans[planIndex].exercises {
            if exo.name == exoName { return }
        }
        // All ok, add to exercises. append will add as last exercise, insert(at: 0) would append as first.
        plans[planIndex].exercises.append(Exercise(name: exoName))
    }
}

That will be a bit difficult to use id, as you do not know directly what it is.

You have 2 options:

• create a planIndex
• identify plan by its name, as it must be unique.

Second solution is the best.

Code will become:

• to make sure name is unique:

    func addPlan(_ item: String) {
        if item == "" { return }
        // Also test item does not exist there already
        for plan in plans {
            if item == plan.name { return }
        }
        // now we can add safely
        let plan = Plan(name: item, exercises: [])
        plans.insert(plan, at: 0)
    }

• use name to identify plan

    func addExercise(to planName: String, exoName: String) {
        if exoName == ""  { return }

        // find the index, which is unique
        guard let planIndex = plans.firstIndex(of: planName) else { return }

        // Also test exoName does not already exist in this plan
        for exo in plans[planIndex].exercises {
            if exo.name == exoName { return }
        }
        // All ok, add to exercises. append will add as last exercise, insert(at: 0) would append as first.
        plans[planIndex].exercises.append(Exercise(name: exoName))
    }
}

This should now work properly. If not, explain. If OK, don't forget to close the thread.

Exact.

We must work on Strings:

let plansNames = plans.map { $0.name }
guard let planIndex = plansNames.firstIndex(of: planName) else { return }