问题
I'm currently making a drawing application in Swift, but I wanted the page to be able to expand if the user wanted more room. I figured that I would use a UIScrollView to scroll around the canvas, but I wanted it to expand whenever the user went to the edge of the page, and for the UIImageView that I am drawing on to expand with it. Does anyone know how I would go about doing this? Thanks!
回答1:
In storyboard, drag a UIView into your UIScrollView then constrain that view to all sides of the scroll view. Then set the width to whichever value you would like (I would recommend to control drag from your view to the root view of the view controller and select equal widths), then give it a height constraint. Next, you need to connect an IBOutlet to your view controller code for the height constraint you set on the content view inside the scroll view. When you need to extend the page, add to the value of the height constraint and call layoutIfNeeded() on the scroll view.
来源：https://stackoverflow.com/questions/37366954/making-an-expanding-scrollview