Image+aspectRatio.swift

extension Image {
    /// This helps achieving what `UIView.ContentMode.scaleAspectFit` and `.scaleAspectFill` do in UIImageView.contentMode
    ///
    /// The difference between Image.containerAspectRatio (this) and SwiftUIs View.aspectRatio is that the first applies the 
    /// aspect ratio to the view that contains the image, rather than to the image itself.
    ///
    /// So in the following example:
    /// - The first image will scale to a square but the contentMode does not do anything to prevent stretching and wether you use .fit or .fill does not matter.
    /// - The second image will resize to fit inside a square while maintaining its aspect ratio, similar to how a UIImageView with contentMode set to scaleAspectFit behaves.
    /// - The third image will resize to fill inside a square while maintaining its aspect ratio similar to how a UIImageView with contentMode set to scaleAspectFill behaves.
    ///
    /// ```
    /// VStack {
    ///     Image("apple")
    ///         .resizable()
    ///         .aspectRatio(1, contentMode: .fit)
    ///     Image("pear")
    ///         .resizable()
    ///         .containerAspectRatio(1, contentMode: .fit)
    ///     Image("strawberry")
    ///         .resizable()
    ///         .containerAspectRatio(1, contentMode: .fill)
    /// }
    /// ```
    func containerAspectRatio(_ aspectRatio: Double, contentMode: SwiftUI.ContentMode) -> some View {
        // Since the content is in the overlay the first contentMode param doesn't influence anything
        Color.clear
            .aspectRatio(aspectRatio, contentMode: .fit)
            .overlay(self.aspectRatio(contentMode: contentMode))
    }
}