ios - 使用 JSQMessage 下载后难以让媒体替换占位符

Question

我正在使用 JSQMessage，在显示媒体占位符时遇到一些困难，直到我正确下载它，然后替换为媒体。就将消息和媒体添加到服务器而言，我的一切工作正常，只是无法用它来替换占位符。

目前，我有一个函数可以查询数据库并提取消息对象数组，然后循环遍历并为每个对象调用此函数以输出并将其添加到我的消息线程中。我正在努力弄清楚为什么“messageToAdd.isMediaMessage”部分在从服务器下载后没有用实际媒体替换占位符。有谁知道我应该如何处理这个问题，以确保它添加带有占位符的消息，然后在媒体正确下载后进行替换？

- (void)addMessage:(PFObject *)object
{
    id<JSQMessageMediaData> messageMedia = nil;
    PFObject *user = object[@"messageSender"];
    [users addObject:user];
    NSString *name = @"";
    if(user[@"profileFName"] && user[@"profileLName"])
        name= [NSString stringWithFormat:@"%@ %@",user[@"profileFName"],user[@"profileLName"]];
    else
        name= [NSString stringWithFormat:@"%@ %@",user[@"consultantFName"],user[@"consultantLName"]];

    if([object[@"messageFileType"] isEqual: @"video"]){
        JSQVideoMediaItem *messageMedia = [[JSQVideoMediaItem alloc] init];
        messageMedia.fileURL = nil;
        messageMedia.isReadyToPlay = NO;
        messageToAdd = [JSQMessage messageWithSenderId:user.objectId displayName:name media:messageMedia];

    } else if ([object[@"messageFileType"] isEqual: @"image"]){
        JSQPhotoMediaItem *messageMedia = [[JSQPhotoMediaItem alloc] init];
        messageMedia.image = nil;
        messageToAdd = [JSQMessage messageWithSenderId:user.objectId displayName:name media:messageMedia];

    } else{
        messageToAdd= [[JSQMessage alloc] initWithSenderId:user.objectId senderDisplayName:name date:object[@"sendDate"] text:object[@"messageContent"]];
    }
    if(isLoadMore)
        [messages insertObject:messageToAdd atIndex:0];
    else
        [messages addObject:messageToAdd];

   // NOT TRIGGERING THESE AFTER MEDIA DOWNLOADED
    if (messageToAdd.isMediaMessage) {
        dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void){
            if ([object[@"messageFileType"] isEqual: @"image"]){
                [object[@"messageMedia"] getDataInBackgroundWithBlock:^(NSData *imageData, NSError *error) {
                    if (!error) {
                        JSQPhotoMediaItem *photoItem = [[JSQPhotoMediaItem alloc] initWithImage:[UIImage imageWithData:imageData]];
                        ((JSQPhotoMediaItem *)messageMedia).image = [UIImage imageWithCGImage:photoItem.image.CGImage];
                        [self.collectionView reloadData];
                    }
                }];
            }
            else if([object[@"messageFileType"] isEqual: @"video"]){
                PFFile *videoFile = object[@"messageMedia"];
                NSURL *videoURL = [NSURL URLWithString:videoFile.url];
                ((JSQVideoMediaItem *)messageMedia).fileURL = videoURL;
                ((JSQVideoMediaItem *)messageMedia).isReadyToPlay = YES;
                [self.collectionView reloadData];
            }
            else {
                NSLog(@"%s error: unrecognized media item", __PRETTY_FUNCTION__);
            }
        });
    }
}

Answer 1

对于遇到相同问题的其他人，我通过查看此处的项目NotificationChat解决了它的工作原理:https://github.com/relatedcode/NotificationChat/blob/master/NotificationChat/Classes/Chat/ChatView.m 。它很好地概述了如何使用 JSQMessage 平台。

这是我修改后的函数，以便您可以看到成品。

- (void)addMessage:(PFObject *)object
{
    PFObject *user = object[@"messageSender"];
    [users addObject:user];

    PFFile *mediaMessage = object[@"messageMedia"];

    NSString *name = @"";
    if(user[@"profileFName"] && user[@"profileLName"])
        name= [NSString stringWithFormat:@"%@ %@",user[@"profileFName"],user[@"profileLName"]];
    else
        name= [NSString stringWithFormat:@"%@ %@",user[@"consultantFName"],user[@"consultantLName"]];

    if([object[@"messageFileType"] isEqual: @"video"]){
        JSQVideoMediaItem *mediaItem = [[JSQVideoMediaItem alloc] initWithFileURL:[NSURL URLWithString:mediaMessage.url] isReadyToPlay:YES];
        mediaItem.appliesMediaViewMaskAsOutgoing = [user.objectId isEqualToString:self.senderId];
        messageToAdd = [[JSQMessage alloc] initWithSenderId:user.objectId senderDisplayName:name date:object.createdAt media:mediaItem];

    } else if ([object[@"messageFileType"] isEqual: @"image"]){
        JSQPhotoMediaItem *mediaItem = [[JSQPhotoMediaItem alloc] initWithImage:nil];
        mediaItem.appliesMediaViewMaskAsOutgoing = [user.objectId isEqualToString:self.senderId];
        messageToAdd = [[JSQMessage alloc] initWithSenderId:user.objectId senderDisplayName:name date:object.createdAt media:mediaItem];

        [mediaMessage getDataInBackgroundWithBlock:^(NSData *imageData, NSError *error)
         {
             if (error == nil)
             {
                 mediaItem.image = [UIImage imageWithData:imageData];
                 [self.collectionView reloadData];
             }
         }];


    } else{
        messageToAdd= [[JSQMessage alloc] initWithSenderId:user.objectId senderDisplayName:name date:object[@"sendDate"] text:object[@"messageContent"]];
    }
    if(isLoadMore)
        [messages insertObject:messageToAdd atIndex:0];
    else
        [messages addObject:messageToAdd];

}