我的表格视图中的第一个可见缩略图无法出现 - 使用 LazyTableImages 示例作为基础
我改编了developer.apple.com上的LazyTableImages示例中的代码，除了无法加载前4行的图像（加载时有4行可见）之外，它一切正常。当我向下滚动并停止时，新行的图像会正确加载，当我向上滚动时，前 4 个图像也会正确加载。所以问题是初始加载。
我使用 fetch 控制器加载表数据，它从 CoreData 数据库读取。在我的 cellForRowAtIndexPath 方法中，我添加了一个额外的检查，如下所示：
if (self.screeningsTable.dragging == NO &&
self.screeningsTable.decelerating == NO && movie.MovieID) {
[self startImageDownload:movie forIndexPath:indexPath];
}
检查该行是否确实具有有效的对象。因此，为了加载第一行的图像，我在从数据库加载数据后添加了 [self loadImagesForOnscreenRows] ，但它不起作用。
您能告诉我应该将 [self loadImagesForOnscreenRows] 放在哪里，以便正确加载第一个图像吗？
I adapted the code from the LazyTableImages example on developer.apple.com and it all works except that it failed to load the images for the first 4 rows (there are 4 rows visible on load). When I scroll down and stop, the new rows' images are loaded correctly and when I scroll back up, the fist 4 images are also loaded correctly. So the problem is the initial loading.
I use fetch controller for loading the table data and it reads from a CoreData database. In my cellForRowAtIndexPath method I added an additional check like this:
if (self.screeningsTable.dragging == NO &&
self.screeningsTable.decelerating == NO && movie.MovieID) {
[self startImageDownload:movie forIndexPath:indexPath];
}
as to check if the row actually has a valid object yet. So in order to load the images of the first rows, I added [self loadImagesForOnscreenRows] after the data has been loaded from the database, but it doesn't work.
Can you tell where I should put the [self loadImagesForOnscreenRows] so the first images are correctly loaded?
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我发现了问题 - TableView reloadData 方法重新加载的速度不够快，因此当
[self loadImagesForOnscreenRows]启动时，单元格还不存在。所以我用[myTable PerformSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:YES]; 替换了[myTable reloadData];，这成功了。希望对某人有帮助。
I found the problem - the TableView reloadData method didn't reload fast enough, so when the
[self loadImagesForOnscreenRows]started, the cells weren't there yet. So I replaced[myTable reloadData];with[myTable performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:YES];which did the trick.Hope that helps someone.