When I mark a protocol with async functions with @MainActor and it's conformance does not specify it's functions are async, it is not executing on main thread. I don't know if this is a bug or not.
For example, given the following protocol and implementation:
@MainActor
protocol MyMainActorProtocol {
func doStuff() async
}
struct MyMainActorStruct: MyMainActorProtocol {
nonisolated init() {}
func doStuff() {
print(">>> \(Thread.isMainThread)")
}
}
When I execute this code:
Task {
let dependency: MyMainActorProtocol = MyMainActorStruct()
print(">>> \(Thread.isMainThread)")
await dependency.doStuff()
}
both print statements run in a background thread.
But with the following adjustments of either
@MainActor
protocol MyMainActorProtocol {
func doStuff()
}
struct MyMainActorStruct: MyMainActorProtocol {
nonisolated init() {}
func doStuff() {
print(">>> \(Thread.isMainThread)")
}
}
or
@MainActor
protocol MyMainActorProtocol {
func doStuff() async
}
struct MyMainActorStruct: MyMainActorProtocol {
nonisolated init() {}
func doStuff() async {
print(">>> \(Thread.isMainThread)")
}
}
I get the correct result, where the body of the function inside the struct runs in the main thread.
Is this expected behavior? What is the explanation behind it.