RemoteImageDownloader *imgView = (RemoteImageDownloader*)[cell viewWithTag:1];
if (imgView == nil)
{
imgView = [[RemoteImageDownloader alloc] initWithFrame:CGRectMake(0.0, 0.0, 50.0, cell.frame.size.height)];
imgView.tag = 1;
[cell.contentView addSubview:imgView];
}
imgView.image = nil;
imgView.backgroundColor = [UIColor grayColor];
imgView.opQueue = self.opQueue;
//[imgView performSelector:@selector(DownloadRemoteImageforURL:withCachingOption:) withObject:[_marrImgUrl objectAtIndex:indexPath.row]];
if ([self checkDocDirectoryforFileName:[[_marrImgUrl objectAtIndex:indexPath.row] lastPathComponent]])
{
[imgView setImage:[UIImage imageWithData:[self checkDocDirectoryforFileName:[[_marrImgUrl objectAtIndex:indexPath.row] lastPathComponent]]]];
}
else
{
[imgView DownloadRemoteImageforURL:[_marrImgUrl objectAtIndex:indexPath.row] withCachingOption:NSURLRequestReloadRevalidatingCacheData isNeedtoSaveinDocumentDirectory:YES];
}
-(void)DownloadRemoteImageforURL:(NSString*)strURL withCachingOption:(NSURLRequestCachePolicy)urlCachePolicy isNeedtoSaveinDocumentDirectory:(BOOL)isNeedSave
{
ImageLoader *subCategoryImgLoader = [[[ImageLoader alloc] initWithUrl:[NSURL URLWithString:strURL]] autorelease];
subCategoryImgLoader.target = self;
subCategoryImgLoader.didFinishSelector = @selector(imageDownloadDidFinishwithData:andOperation:);
subCategoryImgLoader.didFailSelector = @selector(imageDownloadfailedwithErrorDesc:andOperation:);
[self.opQueue setMaxConcurrentOperationCount:2];
if ([self.opQueue operationCount] > 0)
{
NSOperation *lastOperation = [[self.opQueue operations] lastObject];
[subCategoryImgLoader addDependency:lastOperation];
}
[self.opQueue addOperation:subCategoryImgLoader];
if (_actIndicatorView)
{
[_actIndicatorView removeFromSuperview], _actIndicatorView = nil;
}
_actIndicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
_actIndicatorView.tag = 100;
_actIndicatorView.center = self.center;
[self addSubview:_actIndicatorView];
[_actIndicatorView startAnimating];
}
在上面的代码ImageLoader
是NSOperation
的子类。虽然我正在检查操作计数,但是我正在将操作添加到该操作中,但我的操作数为零。如果我犯了错误,请告诉我。我没有得到我所做的错误,所以我得到了零操作计数。没有得到操作计数的操作队列
我创建了队列的实例,它只创建一次,我使用的是同一个实例,而不是一次又一次地创建。添加任何操作后,它显示它有一个操作,但是当我要添加另一个操作时,我得到零计数。
RemoteImageDownloader
是UIImageView
的子类。我在UIViewcontroller
中创建了该实例。
希望现在能够很容易地理解我在做什么。
现在我评论了行[self.opQueue setMaxConcurrentOperationCount:2];
。现在它正在获得手术数量。谁能告诉我为什么这样?
如果新操作总是需要等待上一个操作,为什么要将'maxConcurrentOperationCount'设置为2?你为什么不把它设置为1? –
您是否真的创建了队列实例? – Wain
我已更新我的帖子 – Exploring