How to fix “Protocol 'View' can only be used as a generic constraint because it has Self or associated type requirements”

Paul Hudson    @twostraws    October 14th 2019

Fully updated for Xcode 11.1

This is a particularly confusing problem, and it occurs because SwiftUI relies heavily on opaque return types. The problem happens because of code like this:

 struct ContentView: View {
    var body: View {
        Text("SwiftUI")
    }
}

It feels like such a tiny thing, but the body property is declared as returning View rather than some View. The difference is small but important – you can find out more about it in my article How to use opaque return types in Swift 5.1.

So, to fix the problem use this instead:

 struct ContentView: View {
    var body: some View {
        Text("SwiftUI")
    }
}

Similar solutions…

• SwiftUI tips and tricks
• Displaying a detail screen with NavigationLink
• Building a menu using List
• How to fix “Property declares an opaque return type, but has no initializer expression from which to infer an underlying type”
• How to fix “Function declares an opaque return type, but has no return statements in its body from which to infer an underlying type”