SwiftUI - Pass Enum as Parameter to View

Question

I have an environment object (we'll call it sample for this example) with multiple enums inside. I have a view that I would like to use over and over again instead of duplicating it a bunch of times. Inside that view is a button where I want to set the value of one of the enums.

I'm trying to figure out how to pass that button action as a parameter of the call to the view like this, TestView(enum: sample.enum1, destination: .main)

Here's some code:

class Sample: ObservableObject {

    @Published var enum1: Enum1 = .main
    @Published var enum2: Enum2 = .foo
    @Published var enum3: Enum3 = .add

    enum Enum1 {
        case main
        case test
    }

    enum Enum2 {
        case foo
        case blah
    }

    enum Enum3 {
        case add
        case remove
    }
}

struct MultipleUseView: View {
    @EnvironmentObject var sample: Sample
    @State var enum: Sample
    @State var destination: Sample

    var body: some View {
        Button {
            enum = destination
        } label: {
            "Tap Me"
        }
    }
}

struct TestView: View {
    @EnvironmentObject var sample: Sample

    var body: some View {
        MultipleUseView(enum: sample.enum1, destination: .main)
    }
}

The two @State variables I included in my sample code are just to show what's not working at the moment. All I need to figure out is how to pass those parameters to MultipleUseView, from TestView, so that the button in MultipleUseView ends up with an action of:

sample.enum1 = .main

You may want to paste this code into Xcode and examine the errors. There are quite a few (not just related to your specific issue) — jnpdx
– jnpdx, Commented Aug 2, 2022 at 16:21
I was just typing too fast when writing up the example. Sorry for messing up the class. It's fixed now. Obviously I have this in the actual environment. I'm not asking for help with anything other than how to pass parameters of an enum (and the enum itself) to a view. Everything else already works just fine. My sample code is just to illustrate what I'm talking about. — kittonian
– kittonian, Commented Aug 2, 2022 at 16:24

Asperi · Accepted Answer · 2022-08-19 15:49:44Z

1

With pretty amount of doubts I would suppose that you want to write a value into environment object by key path... if I'm right then it can be done as follows

struct MultipleUseView<T>: View {
    @EnvironmentObject var sample: Sample

    // bad practice to name vars as keywords, but if you insist...
    var `enum`: ReferenceWritableKeyPath<Sample, T>
    var destination: T

    var body: some View {
        Button {
            sample[keyPath: `enum`] = destination // << here !!
        } label: {
            Text("Tap Me")
        }
    }
}

struct TestView: View {
    @EnvironmentObject var sample: Sample

    var body: some View {
        MultipleUseView(enum: \.enum1, destination: .main)
    }
}

edited Aug 19, 2022 at 15:49

answered Aug 2, 2022 at 16:36

Asperi

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