RongIM 消息推送 分为二类：
1.远程推送：指 程序在后台 2分钟后被杀死，通过远程推送方式，实现消息通知
2.本地推送：程序在后台存活时，若有消息，将以本地推送方式通知

实现消息推送步骤：
第一步：配置证书 上传P12 证书
具体方式 见：http://www.rongcloud.cn/docs/ios_push.html#push
ps：APP本身一定要打开推送

第二步：处理推送

pragma mark - 推送处理

• (void)registerRongIMPushWith:(UIApplication *)application{

  /**

  • 推送处理1
    */
    if ([application
    respondsToSelector:@selector(registerUserNotificationSettings:)]) {
    //注册推送, 用于iOS8以及iOS8之后的系统
    UIUserNotificationSettings *settings = [UIUserNotificationSettings
    settingsForTypes:(UIUserNotificationTypeBadge |
    UIUserNotificationTypeSound |
    UIUserNotificationTypeAlert)
    categories:nil];
    [application registerUserNotificationSettings:settings];
    } else {
    //注册推送，用于iOS8之前的系统
    UIRemoteNotificationType myTypes = UIRemoteNotificationTypeBadge |
    UIRemoteNotificationTypeAlert |
    UIRemoteNotificationTypeSound;
    [application registerForRemoteNotificationTypes:myTypes];
    }

}
/**

• 推送处理2
  */
  //注册用户通知设置

• (void)application:(UIApplication *)application didRegisterUserNotificationSettings:
  (UIUserNotificationSettings *)notificationSettings {
  // register to receive notifications
  [application registerForRemoteNotifications];
  }

/**

• 推送处理3
  */

• (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
  NSString *token =
  [[[[deviceToken description] stringByReplacingOccurrencesOfString:@"<" withString:@""]stringByReplacingOccurrencesOfString:@">"withString:@""] stringByReplacingOccurrencesOfString:@" " withString:@""];

  [[RCIMClient sharedRCIMClient] setDeviceToken:token];
  }

到此，远程推送基本实现

第三步：本地推送
本地推送需要设置代理方法
Delegate：<RCIMReceiveMessageDelegate,RCIMUserInfoDataSource>
[RCIM sharedRCIM].receiveMessageDelegate = self;
[RCIM sharedRCIM].userInfoDataSource = self;

代理方法如下：

pragma mark - 获取用户信息

• (void)getUserInfoWithUserId:(NSString )userId completion:(void(^)(RCUserInfo userInfo))completion
  {
  if ([userId isEqualToString:@"13501030554"]) {

          NSLog(@"+++++++++++++++++++++++++++++++++");
    return completion([[RCUserInfo alloc] initWithUserId:userId name:@"当前登录用户的用户名" portrait:@"当前登录用户头像的url"]);
  

  }else
  {
  // 根据存储联系人信息的模型，通过 userId 来取得对应的name和头像url，进行以下设置（此处因为项目接口尚未实现，所以就只能这样给大家说说，请见谅）

            NSLog(@"============================");
    
    return completion([[RCUserInfo alloc] initWithUserId:userId name:@"name" portrait:@"http://pic32.nipic.com/20130827/12906030_123121414000_2.png"]);
  

  }

}

pragma mark - 消息接收器代理

//在前台和后台活动状态时收到任何消息都会执行。

• (void)onRCIMReceiveMessage:(RCMessage *)message left:(int)left{

  NSLog(@"活跃状态接受的消息:%@",message);

}

• (BOOL)onRCIMCustomLocalNotification:(RCMessage *)message withSenderName:(NSString *)senderName{

  NSLog(@"发送者是 ：%@",senderName);
  NSLog(@"发送的消息是 : %@",message);
  return NO;
  }

ps：需要注意的两点：

1. • (BOOL)onRCIMCustomLocalNotification:(RCMessage *)message withSenderName:(NSString *)senderName 返回值应该为NO
     2.一定要设置用户信息- (void)getUserInfoWithUserId:(NSString )userId completion:(void(^)(RCUserInfo userInfo))completion