MainActor is a new attribute introduced in Swift 5.5 as a global actor providing an executor which performs its tasks on the main thread. When building apps, it’s important to perform UI updating tasks on the main thread, which can sometimes be challenging when using several background threads. Using the @MainActor attribute will help you make sure your UI is always updated on the main thread.
If you’re new to Actors in Swift, I recommend reading my article Actors in Swift: how to use and prevent data races. Global actors act similar to actors, and I won’t go into much detail on how actors work in this post.
@globalActor
actor SwiftLeeActor {
static let shared = SwiftLeeActor()
}