Understanding AVPlayerItem Status and Implementing a Delayed Video Preview

In this article, we will delve into the world of AVPlayerItem status and explore how to implement a delayed video preview using AVPlayer. Specifically, we’ll discuss why using a while loop can be problematic and provide an alternative approach that leverages key-value observing.

The Problem with While Loops

When working with AVPlayer, it’s common to encounter situations where the player item needs to transition from one state to another, such as from unknown to readyToPlay. In our quest to create a seamless user experience, we might resort to using while loops to wait for the desired state to change. However, this approach can lead to issues.

The primary concern with while loops is that they can overwhelm the system, causing performance degradation and potential crashes. This is because the loop continuously checks the player item’s status without allowing any other processes or updates to occur in the meantime.

Understanding AVPlayerItem Status

Before we dive into solutions, let’s understand the different states an AVPlayerItem can be in:

• AVPlayerItem.Status.unknown: The media hasn’t been loaded and is not yet enqueued for playback.
• AVPlayerItem.Status.readyToPlay: The media has been loaded and is ready for use. This is the state we’re interested in.
• AVPlayerItem.Status.failed: The player item failed to load or play the media.

Key-Value Observing

To avoid using while loops, we can leverage key-value observing (KVO) to monitor changes to the player item’s status. KVO allows us to observe specific properties and receive notifications when they change.

In our code, we’ve already set up KVO for the AVPlayerItem.status property by adding an observer in the following lines:

playerItem1.addObserver(self,
                    forKeyPath: #keyPath(AVPlayerItem.status),
                    options: [.old, .new],
                    context: &playerItemContext)

This allows us to observe changes to the player item’s status and react accordingly.

Implementing a Delayed Video Preview

Now that we’ve discussed why while loops can be problematic and how to use KVO, let’s implement a delayed video preview using AVPlayer.

Our goal is to display a frozen video preview for a short duration before playing it. We’ll achieve this by delaying the playback of the player item until its status changes from unknown to readyToPlay.

Here’s the modified code that implements the delayed video preview:

override func observeValue(forKeyPath keyPath: String?,
                           of object: Any?,
                           change: [NSKeyValueChangeKey : Any]?,
                           context: UnsafeMutableRawPointer?) {

    // Only handle observations for the playerItemContext
    guard context == &playerItemContext else {
        super.observeValue(forKeyPath: keyPath,
                           of: object,
                           change: change,
                           context: context)
        return
    }

    if keyPath == #keyPath(AVPlayerItem.status) {
        let status: AVPlayerItem.Status
        if let statusNumber = change?[.newKey] as? NSNumber {
            status = AVPlayerItem.Status(rawValue: statusNumber.intValue)!
        } else {
            status = .unknown
        }

        // Switch over status value
        switch status {
        case .readyToPlay:
            // Player item is ready to play.

            playerQueue = AVQueuePlayer(playerItem: playerItem1)
            self.playerQueue?.play()

            // Create the video preview layer
            playerLayer = AVPlayerLayer(player: playerQueue)
            playerLayer.frame = (camPreview?.bounds)!
            playerLayer?.layoutIfNeeded()
            playerLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill

            camPreview?.layer.insertSublayer(playerLayer, above: previewLayer)

            // Start playing the video
            playerLooper = AVPlayerLooper(player: playerQueue, templateItem: playerItem1)
            self.playerQueue?.play()

        case .failed:
            // Player item failed. See error.
        case .unknown:
            // Player item is not yet ready.
        }
    }
}

In this modified code, we’ve added a conditional statement to check the player item’s status. If it’s readyToPlay, we create the video preview layer and start playing the video using the play() method.

Conclusion

By leveraging key-value observing and avoiding while loops, we can implement a delayed video preview using AVPlayer. This approach provides a better user experience by displaying a frozen video preview for a short duration before playing it.

We hope this article has provided a clear understanding of how to handle AVPlayerItem status changes and implement a delayed video preview in your iOS applications.

Last modified on 2025-03-18