Error in my code

Question

Hi everyone! I was working on a playground in Swift Playground and I got an error. I can't understand what this error means, can anyone help me?

This is my code:

struct Preview: View {
    @State var isPlaying = true
    @State var num1 = 60
    @State var num2 = 150

    var body: some View {
        if isPlaying == true {  // ERROR: Only concrete types such as structs, enums and classes can conform to protocols 
// Required by static method 'buildBlock' where 'C0' = ()
            num1 += 1
            print("\(num1)")
        }
    }
}

Thanks.

SwiftUI

143

Posted by

Balvir-255

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Answer 1

What do you want to achieve ?

isPlaying is a state var. Where is it changed ?
you cannot have the statement num += 1 directly here
body must build a view.

Here is a code that works (does it do what you want is another question:

struct Preview: View {
    @State var isPlaying = true
    @State var num1 = 60
    @State var num2 = 150
    @State var moreText = ""  // To see what's going on

    var body: some View {
        Button("Change") {
            isPlaying.toggle()  // State var changes here
        }

        Text("Hello\(moreText)")
            .onChange(of: isPlaying, perform: { _ in
                if isPlaying {
                    num1 += 1
                    print("\(num1)")
                    moreText = ""
                } else { moreText = " log \(num1+1) on change"}
          })

    }
}

Posted by

Claude31

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Answer 2

What do you want to achieve ?

isPlaying is a state var. Where is it changed ?
you cannot have the statement num += 1 directly here
body must build a view.

Here is a code that works (does it do what you want is another question:

struct Preview: View {
    @State var isPlaying = true
    @State var num1 = 60
    @State var num2 = 150
    @State var moreText = ""  // To see what's going on

    var body: some View {
        Button("Change") {
            isPlaying.toggle()  // State var changes here
        }

        Text("Hello\(moreText)")
            .onChange(of: isPlaying, perform: { _ in
                if isPlaying {
                    num1 += 1
                    print("\(num1)")
                    moreText = ""
                } else { moreText = " log \(num1+1) on change"}
          })

    }
}

Posted by

Claude31

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Error in my code

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