How to create a foreach loop with an empty range

Question

In my app I create a list of parents. Each Parent navigationlinks to a subview of children. When I add a new parent, my subview crashes because there are no children yet. I think the issue is related to Range(0...0) what is still a range that loops once. How can I have an empty loop if indices is nil?

ForEach (appState.parents[parentIndex].children?.indices ?? Range(0...0), id: \.self) { childIndex in
    NavigationLink (destination: PuppetsView(parentIndex: self.parentIndex, childIndex: childIndex).environmentObject(self.appState)) {
        Text(self.appState.parents[self.parentIndex].children![childIndex].name) // Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value
    }
}

An *empty* range would be `0..<0` – Martin R Jun 01 '20 at 11:57 — Martin R, Jun 01 '20 at 11:57

pawello2222 · Answer 1 · 2020-06-01T12:01:19.013

0

You can add an if statement to check if there are some values and only then enter a ForEach loop or provide a default value for your children: [].

if appState.parents[parentIndex].children? != nil {
    ForEach(appState.parents[parentIndex].children!.indices, id: \.self) {...}
}

edited Jun 01 '20 at 12:01

answered Jun 01 '20 at 11:55

pawello2222

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score 0 · Answer 2 · answered Jun 01 '20 at 11:58

0

Here is possible approach

ForEach ((appState.parents[parentIndex].children ?? []).indices, id: \.self) { childIndex in
// ... other code here

answered Jun 01 '20 at 11:58

Asperi

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How to create a foreach loop with an empty range

2 Answers2