这里是我的collectionview的代码它显示记录,但加载真的请告诉我如何实现延迟加载在这我还有一个占位符pic在我的项目
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
CollectionViewCell* cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"MJCell" forIndexPath:indexPath];
// Setup image name
NSString *url = [[RSSOutputData objectAtIndex:indexPath.row]xmllink];
UIImage *img = nil;
NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:url]];
img = [[UIImage alloc] initWithData:data];
cell.MJImageView.image = img;
return cell;
}
现在它工作但很慢.
解决方法
使用GCD进行延迟加载非常容易.
// Create a queue for the operations
dispatch_queue_t queue = dispatch_queue_create("photoList",NULL);
// Start getting the data in the background
dispatch_async(queue,^{
NSData* photoData = [NSData dataWithContentsOfURL:[NSURL URLWithString:object.photoURL]];
UIImage* image = [UIImage imageWithData:photoData];
// Once we get the data,update the UI on the main thread
dispatch_sync(dispatch_get_main_queue(),^{
cell.photoImageView.image = image;
});
});