我所做的基本上就是解决这类问题是这样的:
而不是使用它符合JSQMessageData我使用一种叫做视图模型CoreData对象。
甲视图模型基本上是一个正常NSObject的刚刚从CoreData对象解包的所有必要信息,并且符合JSQMessageData协议 - 提供文本,senderId,以及其他信息(以及媒体消息,如果必要的话)
@interface ChatMessageViewModel : NSObject <JSQMessageData>
@property (nonatomic, strong, readonly) CDChatMessage *chatMessage;
// main properties
@property (nonatomic, copy, readonly) NSString *text;
@property (nonatomic, copy, readonly) NSString *senderId;
@property (nonatomic, copy, readonly) NSString *watcherId;
...
@property (nonatomic, strong, readonly) JSQMessage *mediaMessage;
- (instancetype)initWithChatMessage:(CDChatMessage *)chatMessage;
@end
.m文件看起来是这样的:
@interface ChatMessageViewModel()
@property (nonatomic, strong, readwrite) CDChatMessage *chatMessage;
// main properties
@property (nonatomic, copy, readwrite) NSString *text;
@property (nonatomic, copy, readwrite) NSString *senderId;
@property (nonatomic, copy, readwrite) NSString *watcherId;
...
@property (nonatomic, strong, readwrite) JSQMessage *mediaMessage;
@end
@implementation ChatMessageViewModel
- (instancetype)initWithChatMessage:(CDChatMessage *)chatMessage
if (self = [super init]) {
_chatMessage = chatMessage;
[self unpackViewModel];
}
return self;
}
- (void)unpackViewModel {
self.senderId = self.chatMessage.senderId;
self.text = self.chatMessage.senderId;
self.mediaMessage = [self unpackMediaData];
}
- (JSQMessage *)unpackMediaData {
// Here CDCustomPhotoMediaItem is a subclass of JSQPhotoMediaItem which just lets me create custom look of JSQ media item.
JSQPhotoMediaItem *photoItem = [[CDCustomPhotoMediaItem alloc] init];
return [JSQMessage messageWithSenderId:self.senderId displayName:@"" media:photoItem];
}
我使用NSFetchResultsController我只是把所有的核心数据对象,并把它们变成一成不变的ViewModels获取数据后。
然后在cellForItemAtIndexPath我只是把这个:
cell.mediaView = [viewModel.media mediaView];
这种方法创建仅包含由JSQ聊天库所需的必要信息块漂亮的不可变的包装。另外,您可以轻松地为这样的对象编写测试。如果你使用的是swift,你可以使用struct来实现这种目的。
希望我的回答有帮助。请询问你是否需要更详细的答案。 ;-)