iOS tableView实现顶部图片拉伸效果

#define SCREEN_W [UIScreen mainScreen].bounds.size.width #define SCREEN_H [UIScreen mainScreen].bounds.size.height #define TOP 200 //顶部预留  #import "ViewController.h"  @interface ViewController ()<UITableViewDataSource,UITableViewDelegate> @property (nonatomic,strong)UITableView *tableV; @end  @implementation ViewController  - (void)viewDidLoad {  [super viewDidLoad];   [self creatTableView]; }  - (void)creatTableView {  self.automaticallyAdjustsScrollViewInsets = NO;  self.tableV = [[UITableView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_W, SCREEN_H) style:UITableViewStylePlain];  self.tableV.contentInset = UIEdgeInsetsMake(TOP, 0, 0, 0);    self.tableV.delegate = self;  self.tableV.dataSource = self;    //创建顶部图片  UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, -TOP, SCREEN_W, TOP)];  imageView.tag = 1000;    //更改图片显示模式 根据图片原有尺寸进行显示 将多余部分切除  imageView.contentMode = UIViewContentModeScaleAspectFill;    //多余部分隐藏  imageView.clipsToBounds = YES;    imageView.image = [UIImage imageNamed:@"pic"];    [self.view addSubview:_tableV];  [self.tableV addSubview:imageView]; }  - (void)scrollViewDidScroll:(UIScrollView *)scrollView {  float offSet = scrollView.contentOffset.y;    if (offSet < -200)  {   UIImageView * tempImageView = (UIImageView*)[self.view viewWithTag:1000];      CGRect f = tempImageView.frame;   //保持图片原点仍为屏幕左上方   f.origin.y = offSet;   //保证图片根据滑动高度拉伸   f.size.height = -offSet;   //给图片重新设置坐标   tempImageView.frame = f;  } }  - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {  return 10; }  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {  static NSString *cell = @"cell";  UITableViewCell *myCell = [tableView dequeueReusableCellWithIdentifier:cell];  if (!myCell) {   myCell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cell];  }  myCell.textLabel.text = @"我是 cell";  return myCell; }  @end