how do I make a swiftui viewmodifier that accepts any object?

Question

I have a quite few reusable viewmodifiers in my projects, but I have never been able to make one that accepts any object instead of a specific object.

Fx. in below viewmodifier, how would I make it accept any object instead of just "StopContent" so I didn't have to write a new viewModifier each time I wanted to use it on a new object?

struct DragToDeleteContent: ViewModifier {
    
    let stopContent:StopContent
    @Binding var contentArray: [StopContent]
    @State private var deleted:Bool = false
    
    func body(content: Content) -> some View {
        return content
            .dragToDelete(deleted: $deleted)
            .onChange(of: deleted, perform: { deleted in
                if deleted { delete() }
            })
    }
    
    func delete() {
        if let arrayIndex = contentArray.firstIndex(of: stopContent) {
            contentArray.remove(at: arrayIndex)
        }
    }
}

score 0 · Accepted Answer · answered May 31 '21 at 15:59

Every model confirms with Identifiable protocol so you can make it generic by Identifiable.

here is the possible solution

struct DragToDeleteContent<T: Identifiable>: ViewModifier {
    
    let stopContent: T
    @Binding var contentArray: [T]
    @State private var deleted:Bool = false
    
    func body(content: Content) -> some View {
        return content
            .dragToDelete(deleted: $deleted)
            .onChange(of: deleted, perform: { deleted in
                if deleted { delete() }
            })
    }
    
    func delete() {
        if let arrayIndex = contentArray.firstIndex(where: {$0.id == stopContent.id}) {
            contentArray.remove(at: arrayIndex)
        }
    }
}

Data Model

struct TestModel: Identifiable {
    var id = UUID()
    var name: String
}

Usage

}.modifier(DragToDeleteContent(stopContent: TestModel(name: "Abc"), contentArray: .constant([.init(name: "Xyz"), .init(name: "opq")]))) // I used .constant for the demo purpose. Bind you Identifiable array here.

Thank you, that saved me several 100 lines of redundant code and the frustration of knowing I was missing something important. — lmunck, May 31 '21 at 19:04
Now I just need to figure out how to use it in my singleton class that I use for my drag and drop viewmodifiers. That will probably be a new question :) — lmunck, May 31 '21 at 19:11

how do I make a swiftui viewmodifier that accepts any object?

1 Answers1