ios中屏幕适配

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // 左上角
    // 固定左边和上边,伸缩右边和下边
    self.leftTop.autoresizingMask = UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    
    // 左下角
    // 固定左边和下边,伸缩右边和上边
    self.leftBottom.autoresizingMask = UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    
    // 右上角
    // 固定右边和上边,伸缩左边和下边
    self.rightTop.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    
    // 右下角
    // 固定右边和下边,伸缩左边和上边
    self.rightBottom.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
}

关于ios的控件的AutoresizingMask属性  
 个人测试的一些结果
 
setAutoresizingMask控件的自适应
 
 
    UIViewAutoresizingNone                 = 0,
    UIViewAutoresizingFlexibleLeftMargin   = 1 << 0,
    UIViewAutoresizingFlexibleWidth        = 1 << 1,
    UIViewAutoresizingFlexibleRightMargin  = 1 << 2,
    UIViewAutoresizingFlexibleTopMargin    = 1 << 3,
    UIViewAutoresizingFlexibleHeight       = 1 << 4,
    UIViewAutoresizingFlexibleBottomMargin = 1 << 5

UIViewAutoresizingNone

 
UILabel*    label = [[UILabel alloc] initWithFrame:CGRectMake(50, 100, 200, 40)];
 
[label setAutoresizingMask: UIViewAutoresizingNone];  控件相对于俯视图坐标值不变   
 
CGRectMake(50, 100, 200, 40)

UIViewAutoresizingFlexibleWidth：控件的宽度随着父视图的宽度按比例改变    例如

label宽度为 100     屏幕的宽度为320          当屏幕宽度为480时      label宽度  变为  100*480/320
同理  
UIViewAutoresizingFlexibleHeight相同


UIViewAutoresizingFlexibleLeftMargin  到屏幕左边的距离随着父视图的宽度按比例改变  

例如    
CGRectMake(50, 100, 200, 40)];   
50     屏幕的宽度为320          当屏幕宽度为480时      label宽度  变为  50*480/320
控件变为    
CGRectMake(75, 100, 200, 40)];  

UIViewAutoresizingFlexibleRightMargin
UIViewAutoresizingFlexibleTopMargin
UIViewAutoresizingFlexibleBottomMargin