The alignment with a default value of center that you use to position the background view.
Discussion
議論
Use background(_:alignment:) when you need to place one view behind another, with the background view optionally aligned with a specified edge of the frontmost view.
The example below creates two views: the Frontmost view, and the DiamondBackground view. The Frontmost view uses the DiamondBackground view for the background of the image element inside the Frontmost view’s VStack.