我试图重新创造这种效果 -
UITableView的标题部分中有一个UIImageView。当用户向下滚动时,图像的大小减小并在导航栏下滚动,当它们向上滚动时,UIImageView会扩展并返回到它的原始位置。
适用于iOS的Twitter会对您的个人资料产生影响。
到目前为止,这就是我所知道的 - 代码将在scrollViewDidScroll方法下进行,我将不得不使用2个图像,一个大图像,一个小图像。我需要帮助弄清楚如何在方法中的这两个图像之间进行转换。
答案 0 :(得分:4)
如果你想实现Twitter滚动扩展UIImageView,Yari D' areglia的教程概述了如何做到这一点。你可能会发现它很有用。该链接包含一个视频,以演示所需的效果。
http://www.thinkandbuild.it/implementing-the-twitter-ios-app-ui/
#define IMAGE_VIEW_TAG 100
#define IMAGE_SCROLL_VIEW_TAG 101
#pragma mark - ScrollView Delegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if(scrollView.tag == IMAGE_SCROLL_VIEW_TAG) return;
UITableView * tv = (UITableView*) scrollView;
UITableViewCell * cell = [tv cellForRowAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
UIScrollView * svImage = (UIScrollView*)[cell viewWithTag:IMAGE_SCROLL_VIEW_TAG];
CGRect frame = svImage.frame;
frame.size.height = MAX((_imageHeaderHeight-tv.contentOffset.y),0);
frame.origin.y = tv.contentOffset.y;
svImage.frame = frame;
svImage.zoomScale = 1 + (abs(MIN(tv.contentOffset.y,0))/320.0f);
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return [scrollView viewWithTag:IMAGE_VIEW_TAG];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell * cell;
NSLog(@"Row %@", indexPath);
if(indexPath.row == 0){
static NSString * headerId = @"headerCell";
cell = [tableView dequeueReusableCellWithIdentifier:headerId];
if(!cell) {
// create cell as it doesn't exist
cell = [[UITableViewCell alloc]initWithFrame:CGRectMake(0.0, 0.0, self.view.frame.size.width, _imageHeaderHeight)];
cell.backgroundColor = [UIColor clearColor];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
// image view
UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0.0f, 0.0f, cell.contentView.frame.size.width, _imageHeaderHeight)];
imageView.contentMode = UIViewContentModeScaleAspectFill;
imageView.tag = IMAGE_VIEW_TAG;
imageView.clipsToBounds = YES;
imageView.autoresizingMask = UIViewAutoresizingFlexibleHeight;
UIScrollView * svImage = [[UIScrollView alloc]initWithFrame:imageView.frame];
svImage.delegate = self;
svImage.userInteractionEnabled = NO;
[svImage addSubview:imageView];
// image
svImage.tag = IMAGE_SCROLL_VIEW_TAG;
svImage.backgroundColor = [UIColor blackColor];
svImage.zoomScale = 1.0f;
svImage.minimumZoomScale = 1.0f;
svImage.maximumZoomScale = 2.0f;
[cell.contentView addSubview:svImage];
UIImageView * headerInfo = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image.png"]];
[cell.contentView addSubview:headerInfo];
CGRect headerFrame = headerInfo.frame;
headerFrame.size.height = 149.0f;
headerFrame.origin.y = _imageHeaderHeight - 149.0f;
headerInfo.frame = headerFrame;
}
// cell exists - grab a reference to the image it displays
UIImageView *imageView = (UIImageView*)[cell viewWithTag:IMAGE_VIEW_TAG];
// maybe change the imageView
return cell;
}