Ios4 如何获取视频列表的缩略图？

我想创建一个表视图来列出所有视频信息。我需要从互联网上获取缩略图像

加载视图时，我请求每个视频的缩略图。但当请求完成时，通知中心将通知所有视频对象。因此，所有表单元格将同时更新图像。最后，所有表格单元格都显示最后完成的相同缩略图

奇怪的是，它在IOS5上运行良好。只有当我在IOS4上运行应用程序时，才会发生这种情况

这是我的密码：

-(void)viewDidLoad{

    dataArray = [[NSMutableArray arrayWithContentsOfFile:[[NSBundle mainBundle]pathForResource:@"vedio" ofType:@"plist"]] retain];

    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(receiveNotification:) name:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:nil];

    ctlArray = [[NSMutableArray alloc] init];
    for(int i=0; i<[dataArray count]; i++){
        MPMoviePlayerController * vedio = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL URLWithString:[[dataArray objectAtIndex:i]objectForKey:@"url"]]];
        //[vedio prepareToPlay];
        vedio.shouldAutoplay = NO;
        vedio.controlStyle = MPMovieControlStyleEmbedded;

        NSMutableDictionary * data = [NSDictionary dictionaryWithObjectsAndKeys:vedio,@"controller",[NSNumber numberWithInt:i],@"index", nil];
        [ctlArray addObject:data];
        NSMutableArray * allThumbnails = [NSMutableArray  arrayWithObjects:[NSNumber numberWithDouble:2.0],nil];
        [vedio requestThumbnailImagesAtTimes:allThumbnails timeOption:MPMovieTimeOptionExact];

    }
......
}

-(void)receiveNotification:(NSNotification *)notify{

    id pid = [notify object];
    for(int i=0; i<[ctlArray count]; i++){

        NSMutableDictionary * o= [NSMutableDictionary dictionaryWithDictionary:[ctlArray objectAtIndex:i]];

        if (pid == [o objectForKey:@"controller"]) {

            NSDictionary * d = [notify userInfo];

            if([d objectForKey:@"MPMoviePlayerThumbnailImageKey"] != nil){
                UIImage * recvdata = [d objectForKey:@"MPMoviePlayerThumbnailImageKey"];
                [o setObject:recvdata forKey:@"image"];
                [ctlArray replaceObjectAtIndex:i withObject:o ];

                NSIndexPath *durPath = [NSIndexPath indexPathForRow:i inSection:0];
                UITableViewCell * cell = [tblV cellForRowAtIndexPath:durPath];
                if(cell != nil){
                    UIImageView* iv = (UIImageView*)[cell viewWithTag:10000];
                    [iv setImage:recvdata];
                }
            }
            break;
        }
    }
}

-（void）viewDidLoad{
dataArray=[[NSMutableArray arrayWithContentsOfFile:[[NSBundle mainBundle]pathForResource:@“plist”]]retain]类型的“视频”；
[[NSNotificationCenter defaultCenter]添加观察者：自选择器：@selector（receiveNotification:）名称：MPMoviePlayerThumbnailImageRequestDidFinishNotification对象：nil]；
CTLARY=[[NSMUTABLEARY alloc]init]；
对于（int i=0；i通常，您不会获取单元格并直接更新它们。建议的方法是更新基础模型（数据源）。然后，调用
reloadRowsAtIndexPaths:withRowAnimation:
方法，传递索引路径

然后应使用新值重新绘制单元格

还请注意，顾名思义，模拟器不是模拟器，事实上，它运行的库与物理设备中的库不同。可能会发生偏差，在调试时应非常小心假设