在iOS上使用PubNub History API

Question

如何使用History API接收頻道的歷史記錄？ 在文檔中，它表示對[PubNub requestHistoryForChannel:myChannel from:nil to:nil limit:100 reverseHistory:YES]; 成功返回一個數組，但是我的編譯器斷言返回值是空的。 該方法和相關方法的文檔說它們“從歷史記錄中獲取消息”，但是我似乎無法弄清楚消息的獲取位置。 消息發送到的委托方法是否存在？ 請幫幫我。

謝謝

編輯

現在正在接收消息，但不是根據指定的時間間隔。 我正在接收頻道上的所有消息。

- (void)subscribePostChannels:(NSArray *)results withError:(NSError *)error
{
    if (!error) {
        static int SECONDS_IN_TEN_DAYS = 864000;
        for (PFObject *post in results) {
            if ([post.createdAt timeIntervalSinceNow] > (-1) * SECONDS_IN_TEN_DAYS) {
                [self.channelsToSubscribe addObject:post.objectId];
                NSString *pushChannel = [NSString stringWithFormat:@"channel_%@", post.objectId];
                [[PFInstallation currentInstallation] addUniqueObject:pushChannel forKey:@"channels"];
            }
        }
        NSArray *channels = [PNChannel channelsWithNames:self.channelsToSubscribe];
        [PubNub subscribeOnChannels:channels];
        // Now retrieve messages
        NSDate *lastLogin = [PFUser currentUser][@"lastActive"];
        for (PNChannel *channel in channels) {
            [PubNub requestHistoryForChannel:channel from:[PNDate dateWithDate:lastLogin] includingTimeToken:YES withCompletionBlock:^(NSArray *array, PNChannel *channel, PNDate *fromDate, PNDate *toDate, PNError *error) {
                if (!error) {
                    NSLog(@"Last Active: %@", [PFUser currentUser][@"lastActive"]);
                    if (channel == [channels lastObject]) {
                        [PFUser currentUser][@"lastActive"] = [NSDate date];
                        [[PFUser currentUser] saveInBackground];
                    }
                } else {
                    NSLog(@"Error Fetching History: %@", error);
                }
            }];
        }
    } else {
        NSLog(@"Error finding messages. Post channels not subscribed.");
    }
}



- (void)subscribePostChannels:(NSArray *)results withError:(NSError *)error
{
    static int SECONDS_IN_TEN_DAYS = 864000;
    for (PFObject *post in results) {
        if ([post.createdAt timeIntervalSinceNow] > (-1) * SECONDS_IN_TEN_DAYS) {
            [self.channelsToSubscribe addObject:post.objectId];
            NSString *pushChannel = [NSString stringWithFormat:@"channel_%@", post.objectId];
            [[PFInstallation currentInstallation] addUniqueObject:pushChannel forKey:@"channels"];
        }
    }
    NSArray *channels = [PNChannel channelsWithNames:self.channelsToSubscribe];
    [PubNub subscribeOnChannels:channels];
    // Now retrieve messages
    for (PNChannel *channel in channels) {
        NSDate *lastLogin = [PFUser currentUser][@"lastActive"];
        [PubNub requestHistoryForChannel:channel from:[PNDate dateWithDate:lastLogin] to:nil];
    }
}

日志消息指示從歷史記錄接收到消息之后發生lastActive。

Answer 1

我的第二個問題是顯示所有消息，而不是只顯示我想要的消息，這是因為PubNub History API的設置如下：

[PubNub requestHistoryForChannel:myChannel from:nil to:nil limit:100]; 

from: date被視為開始回溯的日期，然后您檢索該日期之前的所有消息，直到to: date。 我以為是from:應該是較早的日期，情況並非如此。

因此，對於我來說，從上次登錄起直到我需要使用的當前日期為止，我都會收到所有消息：

[PubNub requestHistoryForChannel:myChannel from:nil to:[PNDate dateWithDate:lastLogin] limit:100];

感謝PubNub支持人員Craig的幫助。

Answer 2

這似乎對我有用，請讓我知道是否對您有用：

在我的ViewController.m中：

PNConfiguration *myConfig = [PNConfiguration configurationForOrigin:@"pubsub.pubnub.com" publishKey:@"demo" subscribeKey:@"demo" secretKey:@"demo"];

[PubNub setConfiguration:myConfig];
[PubNub connectWithSuccessBlock:^(NSString *origin) {

    PNLog(PNLogGeneralLevel, self, @"{BLOCK} PubNub client connected to: %@", origin);

    PNChannel *myChannel = [PNChannel channelWithName:@"a" shouldObservePresence:YES];
    [PubNub requestHistoryForChannel:myChannel from:nil to:nil limit:100];

}

                     errorBlock:^(PNError *connectionError) {
    if (connectionError.code == kPNClientConnectionFailedOnInternetFailureError) {
        PNLog(PNLogGeneralLevel, self, @"Connection will be established as soon as internet connection will be restored");
    }

    // UIAlert code, etc

}];

在我的AppDelegate中：

- (void)pubnubClient:(PubNub *)client didReceiveMessageHistory:(NSArray *)messages forChannel:(PNChannel *)channel
    startingFrom:(NSDate *)startDate to:(NSDate *)endDate {

PNLog(PNLogGeneralLevel, self, @"PubNub client received history for %@ starting from %@ to %@: %@", channel,
        startDate, endDate, messages);

}

我看到委托的輸出，例如：

2014-07-31 11:12:41.076 PubNubDemo[70859:60b] AppDelegate (0x8e25eb0) PubNub client received history for PNChannel(0x93261e0) a starting from PNDate (0x9330d90) <date: 2014-07-31 18:10:43 +0000; time token: 14068302439622999> to PNDate (0x9330e30) <date: 2014-07-31 18:12:40 +0000; time token: 14068303601434709>: (
"PNMessage (0x9329650): <message: ***********.... 1861 - 2014-07-31 11:10:43, date: (null), channel: a>",
"PNMessage (0x9330830): <message: ************... 1862 - 2014-07-31 11:10:45, date: (null), channel: a>",
"PNMessage (0x9330850): <message: *************.. 1863 - 2014-07-31 11:10:46, date: (null), channel: a>",
"PNMessage (0x9330870): <message: **************. 1864 - 2014-07-31 11:10:47, date: (null), channel: a>",

有關代表的更多信息，請參見：

https://github.com/pubnub/objective-c/tree/master/iOS#--voidpubnubclientpubnub-client-didreceivemessagehistorynsarray-messages-forchannelpnchannel-channel-startingfrompndate-startdate-topndate-enddate

有關觀察者的更多信息，請點擊此處：

https://github.com/pubnub/objective-c/tree/master/iOS#observation-center

這會指導您正確的方向嗎？

geremy