在某些需求下，会要求我们在个人中心的页面，当我下拉拖动视图的时候要求资料背景图放大，类似下面的效果：

效果图：

dd8b240ebb66a5e3266bb822e566e681.gif

下面是实现

1.把图片设置为自适应

    //核心就是这句代码!
    //UIViewContentModeScaleAspectFill高度改变,宽度也会改变
    //不设置那将只会被纵向拉伸
     self.zoomImageView.contentMode=UIViewContentModeScaleAspectFill;

2.重写scrollViewDidScroll方法

-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
   //根据实际选择 加不加上NavigationBarHigth(44,64 或者没有导航条)
    CGFloat y=scrollView.contentOffset.y;
   if(y< -ImageHight)
   {
       CGRect frame= self.zoomImageView.frame;
       frame.origin.y=y;
       frame.size.height=-y;
        self.zoomImageView.frame=frame;
   
   }

}

下面是实现代码，希望对你有所帮助：

#import "ViewController.h"
#define  ImageHight 200.0f
@interface ViewController ()<UITableViewDataSource,UITableViewDelegate>
@property(nonatomic,strong)UITableView *tableView;
//底层背景图
@property(nonatomic,strong)UIImageView *zoomImageView;
//图像
@property(nonatomic,strong)  UIImageView *circleView;
//昵称
@property(nonatomic,strong)UILabel *label;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.title=@"拖动列表时,放大列表顶部的图片";
    //1.初始化_tableView
    self.tableView = [[UITableView alloc]initWithFrame:self.view.bounds style:UITableViewStylePlain];
    //2.设置代理
    self.tableView.dataSource=self;
    self.tableView.delegate=self;
    
    //3.设置contentInset属性（上左下右 的值）
    self.tableView.contentInset = UIEdgeInsetsMake(ImageHight+64, 0, 0, 0);
    //4.添加tableView
    [self.view addSubview:self.tableView];

    //5.配置ImageView
    self.zoomImageView=[[UIImageView alloc]initWithImage:[UIImage imageNamed:@"123.jpg"]];
    self.zoomImageView.frame=CGRectMake(0, -ImageHight , self.view.frame.size.width, ImageHight);
    
    //核心就是这句代码!
    //UIViewContentModeScaleAspectFill高度改变,宽度也会改变
    //不设置那将只会被纵向拉伸
    self.zoomImageView.contentMode=UIViewContentModeScaleAspectFill;
    [self.tableView addSubview: self.zoomImageView];
   
    
    //6.设置autoresizesSubviews让子类自动布局
    self.zoomImageView.autoresizesSubviews = YES;
    
    self.circleView = [[UIImageView alloc]initWithFrame:CGRectMake(10, ImageHight-50, 40, 40)];
     self.circleView.backgroundColor = [UIColor redColor];
     self.circleView.layer.cornerRadius = 7.5f;
     self.circleView.image = [UIImage imageNamed:@"123.jpg"];
     self.circleView.clipsToBounds = YES;
     self.circleView.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;//自动布局，自适应顶部
    [_zoomImageView addSubview:_circleView];
    
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(60, ImageHight-40, 280, 20)];
      self.label.textColor = [UIColor whiteColor];
      self.label.text = @"SunnyYoung";
      self.label.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;//自动布局，自适应顶部
    [_zoomImageView addSubview: self.label];
    //解决tableView  在nav 遮挡的时候 还会透明的显示问题;
    self.edgesForExtendedLayout=UIRectEdgeNone;

}

// 改变frame值
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
   //根据实际选择 加不加上NavigationBarHigth(44,64 或者没有导航条)
    CGFloat y=scrollView.contentOffset.y;
   if(y< -ImageHight)
   {
       CGRect frame= self.zoomImageView.frame;
       frame.origin.y=y;
       frame.size.height=-y;
        self.zoomImageView.frame=frame;
   
   }

}
#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 20;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:@"Jay"];
    if(cell==nil){
        cell=[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Jay"];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
        cell.separatorInset=UIEdgeInsetsZero;
        cell.clipsToBounds = YES;
    }
    
    cell.textLabel.text = [NSString stringWithFormat:@"第-%ld-天 ",indexPath.row];
    
    return cell;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    
}

@end