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