iOS UI布局自适应处理

1、sizeToFit的使用

    label.text=@"优";
    label.font=[UIFont systemFontOfSize:12];
    label.textColor=[UIColor grayColor];
    [label sizeToFit];
    label.frame=CGRectMake(SCREEN_WIDTH - label.frame.size.width-15, 7, label.frame.size.width, label.frame.size.height);