Why ForEach cannot include extra logic?

Question

Hi! I am trying to add some logic in ForEach to compute the views, but XCode does not allow that. Can you tell me why?

ForEach(0...10, id: \.self, content: {
 i in                   
 let s : Int = i
 return Text("abc")
}

XCode will return error message for the above coce: Cannot convert value of type '(_) -> _' to expected argument type '(_.Element) -> _'

However, the code below will work:

ForEach(0...10, id: \.self, content: {
i in                  
return Text("abc")
}

I looked at the declaration of ForEach, but couldn't find why it doesn't accept the "let" statement.

init(_ data: Data, @ViewBuilder content: @escaping (Data.Element) -> Content)

I understand that if I put the logic in a separate structure view for each cell, I can get the code work, but just trying to get a better understanding on SwiftUI and posted this question.

Thank you!

SwiftUI

1.2k

Posted by

ssshhh

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Answer 1

This will work:

struct ContentView: View {
   
    var body: some View {
        List {
            ForEach(0...200, id: \.self) { i -> Text in
                let s : Int = i*i
                return Text("Text \(s)")
            }
        }
    }
}

Now, closure knows what to return (Text)

Without the let declaration, compiler can infer the type from a single line.

Of course, in this case you can even write simpler form without return. Everything is implicit

            ForEach(0...200, id: \.self) { _ in
                Text("abc")
            }

Posted by

Claude31

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Answer 2

This will work:

struct ContentView: View {
   
    var body: some View {
        List {
            ForEach(0...200, id: \.self) { i -> Text in
                let s : Int = i*i
                return Text("Text \(s)")
            }
        }
    }
}

Now, closure knows what to return (Text)

Without the let declaration, compiler can infer the type from a single line.

Of course, in this case you can even write simpler form without return. Everything is implicit

            ForEach(0...200, id: \.self) { _ in
                Text("abc")
            }

Posted by

Claude31

Add a Comment

Answer 3

Did it work for you ? Thanks to report and close the thread.

Posted by

Claude31

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Answer 4

Thank you Claude31!

Posted by

ssshhh

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Why ForEach cannot include extra logic?

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