iPhone SDK：延迟加载scrollView图片的问题
我的应用程序涉及一个滚动视图，其中包含用户通过修改后的 ELCImagePicker 选择的图像视图。所选择的图片通常是 5 MB 以上的高质量照片，并且用户通常会一次选择至少十几张图片。目前，我正在加载照片，如下所示：
-(void)loadViewWithPage: (int)page
{
if (page > 0 && page < [Album count]) {
[scrollView addSubview:[Album objectAtIndex:page]];
}
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)sender
{
CGFloat pageWidth = scrollView.frame.size.width;
int page = floor((scrollView.contentOffset.x - pageWidth) / pageWidth) + 1;
[self loadViewWithPage:page + 1];
}
其中相册是将照片存储为 imageView 的位置。
当用户不想破坏应用程序并一次滚动浏览照片时，这种方法非常有效，但当他/她尝试滚动整个选择时，这种方法就会失败。除非用户在每张照片后停下来，否则页面都是空白的。我尝试使用scrollViewDidScroll ala PageControl示例，但由于照片都很大，所以滞后非常明显。
有什么办法可以顺利加载照片吗？
My app involves a scrollView containing imageViews chosen by the user through a modified ELCImagePicker. The chosen pictures will typically be high quality photos at 5 MB+ and the user will usually choose at least a dozen pictures at a time. Currently, I am loading the photos as below:
-(void)loadViewWithPage: (int)page
{
if (page > 0 && page < [Album count]) {
[scrollView addSubview:[Album objectAtIndex:page]];
}
}
-(void)scrollViewDidEndDecelerating:(UIScrollView *)sender
{
CGFloat pageWidth = scrollView.frame.size.width;
int page = floor((scrollView.contentOffset.x - pageWidth) / pageWidth) + 1;
[self loadViewWithPage:page + 1];
}
Where Album is where the photos are stored as imageViews.
This works great when the user is not trying to break the app and scroll through the photos one at a time, but fails miserably when he/she tries to scroll through the entire selection. The pages are blank unless the user stops after each photo. I tried using scrollViewDidScroll ala PageControl sample, but since the photos are all huge the lag is very visible.
Is there any way of loading the photos smoothly?
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我遇到了类似的情况，并通过创建 NSOperation 的自定义子类来处理它，该子类将在单独的线程中加载图像，然后通过调用主线程上的方法来显示它们。
加载图像时我显示了一个 UIActivityView
希望有帮助。
I had a similar situation and dealt with it by creating a custom subclass of NSOperation which would load the images in a separate thread and then display them by calling a method on the main thread.
While the image was loading I displayed a UIActivityView
Hope that helps.
如果您使用
scrollViewDidEndDecelerating它只会在滚动视图停止时触发。我会使用scrollViewDidScroll来实现这一点。 （它也在他们的示例中使用）if you use
scrollViewDidEndDeceleratingit will only fire when the scrollview stops. I would usescrollViewDidScrollfor that. (it's also used in their examples)