UIVIew autoresizingMask

typedef NS_OPTIONS(NSUInteger, UIViewAutoresizing) {
    UIViewAutoresizingNone                 = 0,      //不进行自动调整
    UIViewAutoresizingFlexibleLeftMargin   = 1 << 0, //自动调整与superview左侧距离，右侧距离保持不变
    UIViewAutoresizingFlexibleWidth        = 1 << 1, //自动调整控件自身宽度，保证与superview左右距离不变
    UIViewAutoresizingFlexibleRightMargin  = 1 << 2, //自动调整与superview右侧距离，左侧距离保持不变
    UIViewAutoresizingFlexibleTopMargin    = 1 << 3, //自动调整与superview顶部距离，底部距离保持不变
    UIViewAutoresizingFlexibleHeight       = 1 << 4, //自动调整控件自身高度，保证与superview上下距离不变
    UIViewAutoresizingFlexibleBottomMargin = 1 << 5  //自动调整与superview底部距离，顶部距离保持不变
};

UIVIew autoresizingMask

原文：http://www.cnblogs.com/woaixixi/p/4511804.html