SwiftUI是否向后兼容iOS12.x及更高版本？

Question

如果我有一个用SwiftUI制作的应用程序，它是否适用于iOS13以下的iOS？

Answer 1

我刚刚在Xcode11中检查了它，并可以确认它不会向后兼容，这可以在Swiftui的视图实现中看到：

/// A piece of user interface.
///
/// You create custom views by declaring types that conform to the `View`
/// protocol. Implement the required `body` property to provide the content
/// and behavior for your custom view.
@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
public protocol View : _View {

    /// The type of view representing the body of this view.
    ///
    /// When you create a custom view, Swift infers this type from your
    /// implementation of the required `body` property.
    associatedtype Body : View

    /// Declares the content and behavior of this view.
    var body: Self.Body { get }
}