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Xcode – Failed to produce diagnostic for expression for image array

I am trying to utilize the UIImage array in SWiftUI class for forEach loop but Xcode always gives me the error ‘Failed to produce diagnostic for expression;’. I also tried using the Data array but same error. Below is my code. It will be great if someone can point what I am doing wrong?

struct Sample: View {

    let imageArray: [UIImage]

    var body: some View {
        ForEach(imageArray) { image in
            Image(uiImage: image)
        }
    }
}
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3

Answers


  1. Chosen as BEST ANSWER
    0

    I was able to fix the problem by adding id in ForEach loop. Below is how my code looks now.

    struct ImageData: Identifiable {
    let id = UUID()
    let image: UIImage
}

struct Sample: View {

    let imageDataArray: [ImageData]

    var body: some View {
        ForEach(imageDataArray) { imageData in
            Image(uiImage: imageData.image)
        }
    }
}

    What I learned from here is, for objects such as UIImage, if you need to enumerate, you must add id property on the ForEach loop. To solve the problem, I created a model class containing id and image property and enumerated it.


  2. 0

    The ForEach operator requires elements of the array to conform to identifiable. For something like UIImage, you can just pass self.

    var body: some View {
    ForEach(imageArray, id: .self) { image in
        Image(uiImage: image)
    }
}

    Personally, I would also wrap it in a Stack, just to be explicit

    var body: some View {
    VStack {
        ForEach(imageArray, id: .self) { image in
            Image(uiImage: image)
        }
    }
}
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  3. 0

    this works for me:

    import SwiftUI

@main
struct TestApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}
struct Sample: View {
    let imageArray: [UIImage]
    
    var body: some View {
        ForEach(imageArray, id: .self) { image in
            Image(uiImage: image)
        }
    }
}

struct ContentView: View {
    @State var imageArray: [UIImage] = []
    
    var body: some View {
        Sample(imageArray: imageArray)
            .onAppear {
                if let img = UIImage(systemName: "globe") {
                    imageArray.append(img)
                }
            }
    }
}
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