#define sclae  2.5 #define HeadViewHeight (SCREEN_WIDTH/sclae)

@interface PersonalCenterViewController

@property (nonatomic,strong) UIImageView* headView;

@property (strong, nonatomic) UITableView *tableView; @property (nonatomic,assign) CGRect oldFrame;

@end

- (void)creatHeadView{       self.headView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, HeadViewHeight)];     self.headView.backgroundColor = [UIColor clearColor];     self.oldFrame = self.headView.frame; //    _headView.contentMode = UIViewContentModeScaleAspectFit;          [self.view addSubview:_headView];      _headView.image = [UIImage imageNamed:@"背景"];          [self.view bringSubviewToFront:self.tableView];     self.tableView.backgroundColor = [UIColor clearColor];

    UIView *tabHead = [[UIView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, HeadViewHeight)];     self.tableView.tableHeaderView = tabHead;

     }

#pragma mark  delegate

-(void)scrollViewDidScroll:(UIScrollView *)scrollView{          //self.navgationBar.backgroundImage = [UIImage imageNamed:@""];     CGFloat yOffset  = scrollView.contentOffset.y;     NSLog(@"%f",yOffset);          if (scrollView == self.tableView) {         if (yOffset<HeadViewHeight) {             CGFloat alpha = yOffset/HeadViewHeight;             //self.navgationBar.backgroundColor = [[UIColor whiteColor]colorWithAlphaComponent:alpha];         }else{                         // self.navgationBar.backgroundColor = [UIColor whiteColor];         }              }          if (yOffset>=0) {                  CGRect frame = self.oldFrame;         frame.origin.y = frame.origin.y - yOffset;         self.headView.frame = frame;              }else{                  CGRect frame = self.oldFrame;         frame.size.height = frame.size.height - yOffset;         frame.size.width = frame.size.height * sclae;         frame.origin.x = self.oldFrame.origin.x - (frame.size.width -self.oldFrame.size.width)/2;         self.headView.frame = frame;     } }