我正在使用一个 Objective-C 应用程序，该应用程序具有一个具有全屏水平滚动 UICollectionView 的场景。我目前有一个函数，每次在滚动过程中屏幕上出现一个新单元格时都会被调用，这需要大约 3-4 秒的时间来运行并编辑新出现的单元格中的 ui 元素。因此，每次新单元格进入屏幕时，我的应用程序都会延迟大约 4 秒，然后继续正常滚动。

有没有一种方法可以编辑此函数并将其放在后台线程上，以便滚动时不会有 4 秒的延迟，而是无缝、不间断的滚动？我知道此解决方案会导致 ui 元素出现 4 秒的延迟，但只要有无缝滚动，我就可以接受。

编辑:我不认为针对此问题发布代码是个好主意，因为执行加载的函数中的代码需要我购买的视频播放器 api，但我会继续发布下面的方法显示函数的哪些部分编辑 UI。

//variables declared in other parts of the file
KolorEyes *myKolorEyesPlayer;
UICollectionView *collectionViewFollwersFeed;
NSIndexPath *lastPath = nil;

//called repeatedly while scrolling
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{


    if(scrollView==_collectionViewFollwersFeed)
    {

        [self tsLoad]; //function call

    }
}


- (void)tsLoad {

    //calculate index path of cell in the center of the screen
    NSIndexPath *centerCellIndexPath =
    [self.collectionViewFollwersFeed indexPathForItemAtPoint:
     [self.view convertPoint:[self.view center] toView:self.collectionViewFollwersFeed]];

    if(centerCellIndexPath != lastPath) //condition is satisfied if a new cell has been scrolled to the center
    {   
        lastPath = centerCellIndexPath;

        UICollectionViewCell *cell; 
        NSString *CellIdentifier;

        //initialize cell from center path
        CellIdentifier = @"FollowersFeed";
        cell = [_collectionViewFollwersFeed cellForItemAtIndexPath:centerCellIndexPath]; 

        //get respective url for video player
        NSMutableDictionary *dict1=[follwerFeed objectAtIndex:centerCellIndexPath.row];
        NSString *tsstring= [dict1 valueForKey:@"video"];
        NSURL *tsurl = [[NSURL alloc] initWithString:tsstring]; 

        //view that the video will be played in
        UIView *tsView = (UIView *)[cell viewWithTag:99]; 

        //API-specific parameters for video player session
        KolorEyesSessionParams *params = [[KolorEyesSessionParams alloc] init];
        params.delegate = self;
        /* other params properties set like above at this point...
           ...
           ...
        */

        //API-specific initialization
        myKolorEyesPlayer = [[KolorEyes alloc] initWithParams:params];

        //API-specific parameters for video player view
        KolorEyesRenderViewParams *fparams = [[KolorEyesRenderViewParams alloc] init];
        fparams.cameraFieldOfView = 90;
        /* other fparams properties set like above at this point...
           ...
           ...
        */

        //API-specific initializations
        id _tsViewHandle = [myKolorEyesPlayer setRenderView: tsView withParams:fparams];
        [myKolorEyesPlayer setCameraControlMode:kKE_CAMERA_MOTION forView:_tsViewHandle];

        __block KolorEyes *player = myKolorEyesPlayer;

        //error checking
        eKEError err = [myKolorEyesPlayer setAssetURL: tsurl
                                withCompletionHandler:^{
                                    // Media is loaded, play now
                                    [player play];
                                }];

        if (err != kKE_ERR_NONE) {
            NSLog(@"Kolor Eyes setAssetURL failed with error");
        }
    } 
}

最佳答案

您可以定义一个“NSOperationQueue”来运行后台操作，当单元格可见时，您可以将视频加载到 UICollectionView 的单元格。

此外，不要忘记利用 NSOperationQueue 并在不再需要 collectionView 时调用“cancelAllOperations”

关于ios - 使用后台线程在 UICollectionViewCell 上加载视频以创建无缝滚动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41969566/