An integer bit mask that determines how the receiver resizes itself when its superview’s bounds change.
- iOS 2.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
When a view’s bounds change, that view automatically resizes its subviews according to each subview’s autoresizing mask. You specify the value of this mask by combining the constants described in
UIView using the C bitwise OR operator. Combining these constants lets you specify which dimensions of the view should grow or shrink relative to the superview. The default value of this property is
none, which indicates that the view should not be resized at all.
When more than one option along the same axis is set, the default behavior is to distribute the size difference proportionally among the flexible portions. The larger the flexible portion, relative to the other flexible portions, the more it is likely to grow. For example, suppose this property includes the
flexible constants but does not include the
flexible constant, thus indicating that the width of the view’s left margin is fixed but that the view’s width and right margin may change. Thus, the view appears anchored to the left side of its superview while both the view width and the gap to the right of the view increase.
If the autoresizing behaviors do not offer the precise layout that you need for your views, you can use a custom container view and override its
layout method to position your subviews more precisely.