每个ChatData对象都有一个唯一的msgid。@interfaceChatData:RLMObject@propertyNSIntegermsgid;....@end但每次我创建一个新对象时，我都必须查询所有对象并获取最后的msgid。RLMArray*all=[[ChatDataallObjects]arraySortedByProperty:@"msgid"ascending:YES];ChatData*last=[alllastObject];ChatData*newData=[[ChataDataalloc]init];newData.msgid=last.msgid+1;
