- (void)viewDidLoad {
    [super viewDidLoad];
    
    CGRect frame = [[UIScreen mainScreen] bounds];
    
    UIView *view1 = [[UIView alloc]init];
    view1.frame = CGRectMake(100, 100, 100, 100);
    view1.backgroundColor = [UIColor blackColor];
    //允许子视图自适应
    view1.tag = 100;
    view1.autoresizesSubviews = YES;
    [self.view addSubview:view1];
    
    UIView *view2 = [[UIView alloc]init];
    view2.frame = CGRectMake(25, 25, 50, 50);
    view2.backgroundColor = [UIColor whiteColor];
    //设置子视图适应方式
    view2.autoresizingMask =
    UIViewAutoresizingFlexibleLeftMargin   |
    UIViewAutoresizingFlexibleWidth        |
    UIViewAutoresizingFlexibleRightMargin  |
    UIViewAutoresizingFlexibleTopMargin    |
    UIViewAutoresizingFlexibleHeight       |
    UIViewAutoresizingFlexibleBottomMargin ;
    [view1 addSubview:view2];
    
    UIButton *btn = [[UIButton alloc]init];
    btn.frame = CGRectMake(0, frame.size.height-200, 50, 50);
    btn.backgroundColor = [UIColor grayColor];
    [btn setTitle:@"变化" forState:UIControlStateNormal];
    [btn addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
}

-(void)click:(UIButton *)btn{
   UIView *view1 =  [self.view viewWithTag:100];
    CGRect frame = view1.frame;
    view1.frame = CGRectMake(frame.origin.x-20, frame.origin.y-20, frame.size.width+40, frame.size.height+40);
}

UIView的视图自适应

父级view1中，包含一个view2，view1的大小变化时，view2可以根据设定条件，与view1一同变化：

view1先设置属性 ，使子view可以动态改变大小：

view1.autoresizesSubviews =YES;

view2子控件设置autoresizeingMask属性，来决定父view变化，子view做出怎样相应的变化：

    view2.autoresizingMask =

    UIViewAutoresizingFlexibleLeftMargin   |

    UIViewAutoresizingFlexibleWidth        |

    UIViewAutoresizingFlexibleRightMargin  |

    UIViewAutoresizingFlexibleTopMargin    |

    UIViewAutoresizingFlexibleHeight       |

    UIViewAutoresizingFlexibleBottomMargin ;