Xcode 12 / iOS14 Widget "@main and must provide a main static function" error

Question

Using Xcode 12 trying to create Widget app extension to my project.

Upon creating new Widget target I am getting the following error:

'Widget' is annotated with @main and must provide a main static function of type () -> Void or () throws -> Void.

Answer 1

You are using name Widget, there is already a protocol called Widget in SwiftUI framework.

You should use some other name but if you really want to, add module name at start like SwiftUI.Widget

@main
struct Widget: SwiftUI.Widget {
    private let kind: String = "Widget"

    public var body: some WidgetConfiguration {
        IntentConfiguration(kind: kind, intent: ConfigurationIntent.self, provider: Provider(), placeholder: PlaceholderView()) { entry in
            WidgetEntryView(entry: entry)
        }
        .configurationDisplayName("My Widget")
        .description("This is an example widget.")
    }
}

Answer 2

For anyone looking to fix the AppDelegate issue when turning on Mac for an iOS14 project - please consult : iOS Xcode 12.0 Swift 5 'AppDelegate' is annotated with @main and must provide a main static function of type () -> Void or () throws -> Void

The fix is to change "@main" to "@UIApplicationMain"

Answer 3

I got this exact error with the following code:

@main
struct NotesApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

The problem was I named my app logic class App.

Answer 4

I've got the same error with this code :

import WidgetKit

@main
struct WidgetSale: Widget {
    let kind: String = "widgetSale"

    var body: some WidgetConfiguration {
        StaticConfiguration(kind: kind, provider: Provider()) { entry in
            widgetSaleEntryView(entry: entry)
        }
        .configurationDisplayName("My Widget")
        .description("This is an example widget.")
    }
}

I solve it by importing swiftUI at the top of the file :

import SwiftUI

Answer 5

In my case I had some code this file:

import SwiftUI

@main
struct FooWidgetExtension: WidgetBundle {
    var body: some Widget {
        SomeWidget()
    }
}

private struct SomeWidget: Widget {
    init() {}

    var body: some WidgetConfiguration {
        EmptyWidgetConfiguration()
    }
}

And the issue was actually you need to have an import WidgetKit as well. The main function must be defined as an extension in that module.