Are Button actions on the MainActor?

Question

rnikander OP

Created Sep ’21

Replies 4

Boosts 2

Views 2.6k

Participants 3

I think they are, but I got myself into a situation with this error:

// Inside a SwiftUI View struct...
let cancelled: @MainActor () -> Void

var body: some View {
   ...
   Button(action: self.cancelled) { Text("Cancel") } // Error here

The compiler reports:

Converting function value of type '@MainActor () -> Void' to '() -> Void' loses global actor 'MainActor'

I originally put that attribute on the cancelled property, because in the passed-in closure, I was doing something that gave me an error about how I had to be on the MainActor.

Boost

Answer 1

OOPer OP

Sep ’21

Better fix the passed-in closure, Adding @MainActor may not be the right solution (even when Xcode suggested that).

0

Answer 2

rnikander OP

Oct ’21

But the passed-in closure is meant to run on the main actor, and it is, it's just that the complier doesn't seem to understand that.

0

Answer 3

OOPer OP

Oct ’21

Seems you expect too much than documented.

0

Answer 4

34534543456789098767654 OP

Dec ’21

It looks like you can work around this using a wrapping closure:

Button(action: { cancelled() }) { Text("Cancel") }

3