UITableView拉伸效果

1. 创建一个UITableView 和一个UIImageView
   

   @property (nonatomic, strong) UITableView *tableView;

   @property (nonatomic, strong) UIImageView *headerImgaeView;

    

2. 初始化
   

    1 - (void)viewDidLoad {
    2     [super viewDidLoad];
    3 
    4     self.tableView = [[UITableView alloc] initWithFrame:CGRectMake(0, 0, 320, 568) style:UITableViewStyleGrouped];
    5     self.tableView.delegate = self;
    6     self.tableView.dataSource = self;
    7     [self.view addSubview:self.tableView];
    8     
    9     
   10     [self layoutHeaderImageView];
   11 }

   viewDidLoad 

3. layoutHeaderImageView

   

    1 - (void)layoutHeaderImageView
    2 {
    3     UIView *headerBackView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 150)];
    4     headerBackView.backgroundColor = [UIColor lightGrayColor];
    5     self.tableView.tableHeaderView = headerBackView;
    6     
    7     self.headerImgaeView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 150)];
    8     self.headerImgaeView.backgroundColor = [UIColor greenColor];
    9     self.headerImgaeView.image = [UIImage imageNamed:@"beautiful.jpg"];
   10     self.headerImgaeView.contentMode = UIViewContentModeScaleAspectFill;
   11     self.headerImgaeView.clipsToBounds = YES;
   12     [headerBackView addSubview:self.headerImgaeView];
   13 
   14 }

   layoutHeaderImageView
4. 滚动偏移的主要方法（这个为UIScrollViewDelegate中的代理方法）
   
   
   

    1 - (void)scrollViewDidScroll:(UIScrollView *)scrollView
    2 {
    3     CGFloat width = self.view.frame.size.width;// 图片宽度
    4     CGFloat yOffset = scrollView.contentOffset.y; //偏移量
    5     
    6     NSLog(@":  %.2f", yOffset);
    7     
    8     if (yOffset < 0) {
    9         CGFloat totalOffset = 150 + ABS(yOffset);
   10         CGFloat f = totalOffset / 150; //缩放系数
   11         
   12         self.headerImgaeView.frame = CGRectMake(-(width * f - width) / 2, yOffset, width * f, totalOffset); //拉伸后的frame是同比例缩放
   13     }
   14     
   15     if (yOffset > 0) {
   16         CGFloat totalOffset = 150 - ABS(yOffset);
   17         CGFloat f = totalOffset / 150;
   18         
   19         self.headerImgaeView.frame = CGRectMake(-(width * f - width) / 2, yOffset, width * f, totalOffset);
   20     }
   21 }

   scrollView