Protocol implementation on a class with @MainActor - how to avoid warnings?-CodePudding

If we have a simple protocol and class implementation like the following;

protocol Solution: ObservableObject {
   var result: String { get set }
   func calc() async
}

@MainActor
class Solve: Solution {
   @Published
   var result: String = ""

   func calc() async { // operate on actors to find the result
      result = "the answer" 
   }
}

Xcode will show a yellow warning : "Main actor-isolated property 'result' cannot be used to satisfy nonisolated protocol requirement" against the class definition of result.

Removing @MainActor will remove the warning, but then we need to manually Dispatch updates to result to ensure they are done on the main thread. Is there a cleaner way to do this? Perhaps by amending the protocol?

CodePudding user response：

Add MainActor to the protocol

@MainActor
protocol Solution: ObservableObject {
   var result: String { get set }
   func calc() async
}

I would give actor a look too, it all depends on the purpose of this class.

If its purpose is to update UI then wrapping the class is natural.

CodePudding user response：

The least intrusive solution is

@MainActor var result: String { get set }