设置图片下拉放大

这里是把这张图片作为tableView的头视图

正常的效果

static CGFloat ImageOriginHeight = 200;

_headerImageView = [FactoryUI createImageViewWithFrame:CGRectMake(0, -ImageOriginHeight, SCREEN_W, ImageOriginHeight) imageName:@"welcome1"];

[_tableView addSubview:_headerImageView];

//设置tableView 内容从ImageOriginHeight开始显示

_tableView.contentInset = UIEdgeInsetsMake(ImageOriginHeight, 0, 0, 0);

-(void)scrollViewDidScroll:(UIScrollView *)scrollView{

//实现下拉放大

//改变scrollview的偏移量来改变图片的frame值

if (scrollView == _tableView) {

//1。获取scrollview的偏移量

CGFloat yOffset = scrollView.contentOffset.y;

CGFloat xOffset = (yOffset + ImageOriginHeight) / 2;

if (yOffset < -ImageOriginHeight) {

CGRect resct = _headerImageView.frame;

//改变imageView的frame

resct.origin.y = yOffset;

resct.size.height = -yOffset;

resct.origin.x = xOffset;

resct.size.width = SCREEN_W + fabs(xOffset) * 2;

_headerImageView.frame = resct;

}

}

}