推送通知中不播放声音

我使用的是 iOS 7，我的推送通知不播放声音。

Strangely, I found there is no setting for sound in the Preference > Notification Center for my app. Following is the screenshots of Notification center for my app:

以下是 Skype 的情况：

您会看到，我的应用程序没有“声音”部分。

有人可以帮忙吗？

Update:

Now I have registered sound in my app. The Notification Center now looks like:

我的通知有声音。看起来不错。

But after I enter the setting of my app, there is initially a 'Sounds' section like Skype, but then the Preference app crashed, and after that, there is no more 'Sounds', just like below:

这可能是苹果的一个bug吗？

您尚未在应用程序中注册音频推送通知。只需在您的 App Delegate 中注册即可：

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //Whatever you have already in your app delegate...

    // Let device know you're going to be sending one of these types of notifications.
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:
        (UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound | UIRemoteNotificationTypeAlert)];

    return YES;
}

这 5 种类型是：

1. UIRemoteNotificationTypeBadge
2. UI远程通知类型声音
3. UIRemoteNotificationTypeAlert
4. UIRemoteNotificationType无
5. UIRemoteNotificationTypeNewsstandContentAvailability

这是文档：注册远程通知 https://developer.apple.com/library/ios/DOCUMENTATION/UIKit/Reference/UIApplication_Class/Reference/Reference.html#//apple_ref/c/tdef/UIRemoteNotificationType

希望有帮助！