I got tried of the compiler telling me that .onChange(of:) was deprecated, so I thought, find, I'll simply stub it out for the older versions. Only... I can't seem to do that? I can use @available(macOS 14, *) to build for that and later, but is there any way to do the opposite? (I'd hoped there was a #if available support, but there isn't.)
I'm using Objective-C++, and I don't know how this translates to Swift, but I use a pattern like this:
if (@available( macOS 10.15, * ))
{
// do it the new way
}
else
{
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
// do it the old way
#pragma clang diagnostic pop
}
This is at the declaration level, not in-function level.
Eg.,
extension View {
#if os(macOS)
@ViewBuilder func onChange<V>(
of value: V,
initial: Bool = false,
perform action: @escaping (V, V) -> Void
) -> some View where V : Equatable {
onChange(of: value) { n in
action(value, n)
}
}
#endif
}
Is @unavailable what you are looking for : https://github.com/apple/swift-evolution/blob/main/proposals/0290-negative-availability.md
It is now possible to write inverted availability conditions by using the new #unavailable keyword:
if #unavailable(iOS 15.0) {
// Old functionality
} else {
// iOS 15 functionality
}
I think @unvavailable would do the trick, but #unavailable does not -- as I said above, it's for a declaration not in-function code. However, that proposal doesn't actually discuss @unavailable.
You should be able to use #else
Except you cannot use either @available or #available in a #if.
