XMPP系列(四）---发送和接收文字消息，获取历史消息功能

今天開始做到最基本的功能发送和接收消息、获取本地历史数据。

先上到眼下为止的效果图：

            

首先是要在XMPPFramework.h中引入数据存储模块：

//聊天记录模块的导入
#import "XMPPMessageArchiving.h"
#import "XMPPMessageArchivingCoreDataStorage.h"
#import "XMPPMessageArchiving_Contact_CoreDataObject.h" //近期联系人
#import "XMPPMessageArchiving_Message_CoreDataObject.h"

然后在XMPPStream中加入数据存储模块。由于XMPP框架默认用CoreData存储数据，并且做好了数据存储，因此我们仅仅须要在合适的地方发送通知处理信息就可以。

 //4.消息模块。这里用单例，不能切换账号登录，否则会出现数据问题。

        _xmppMessageArchivingCoreDataStorage = [XMPPMessageArchivingCoreDataStorage sharedInstance];
        _xmppMessageArchiving = [[XMPPMessageArchiving alloc] initWithMessageArchivingStorage:_xmppMessageArchivingCoreDataStorage dispatchQueue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 9)];
        [_xmppMessageArchiving activate:self.xmppStream];

在数据存储完成后，发送通知：

在XMPPMessageArchivingCoreDataStorage的

- (void)archiveMessage:(XMPPMessage *)message outgoing:(BOOL)isOutgoing xmppStream:(XMPPStream *)xmppStream结尾处加入例如以下通知：

    dispatch_async(dispatch_get_main_queue(), ^{
        [[NSNotificationCenter defaultCenter] postNotificationName:kXMPP_MESSAGE_CHANGE object:nil];
    });

如今去聊天界面获取历史消息吧：

/** 查询聊天记录 */
- (void)getChatHistory
{
    XMPPMessageArchivingCoreDataStorage *storage = [JKXMPPTool sharedInstance].xmppMessageArchivingCoreDataStorage;
    //查询的时候要给上下文
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:storage.messageEntityName inManagedObjectContext:storage.mainThreadManagedObjectContext];
    [fetchRequest setEntity:entity];
    // Specify criteria for filtering which objects to fetch
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"bareJidStr = %@", self.chatJID.bare];
    [fetchRequest setPredicate:predicate];
    // Specify how the fetched objects should be sorted
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"timestamp"
                                                                   ascending:YES];
    [fetchRequest setSortDescriptors:[NSArray arrayWithObjects:sortDescriptor, nil]];
    
    NSError *error = nil;
    NSArray *fetchedObjects = [storage.mainThreadManagedObjectContext executeFetchRequest:fetchRequest error:&error];
    if (fetchedObjects != nil) {
        self.chatHistory = [[NSMutableArray alloc] initWithArray:fetchedObjects];
        //        [NSMutableArray arrayWithArray:fetchedObjects];
    }
    
    [self.messageTableView reloadData];
    
    [self tableViewScrollToBottom];
}

消息接收也调用getChatHistory方法就可以

而消息的发送是：

/** 发送的事件 */
- (void)sendMessage{
    if (_chatTextField.text.length < 1) {
        return;
    }
    XMPPMessage *message = [XMPPMessage messageWithType:@"chat" to:self.chatJID];
    [message addBody:_chatTextField.text];
    [[JKXMPPTool sharedInstance].xmppStream sendElement:message];
    
    _chatTextField.text = @"";
    
    [self tableViewScrollToBottom];
}

demo地址：https://github.com/Joker-King/ChatDemo