如何根据后端标识限制AVPlayer快进快退并获取视频完成时间

Hey there! Let's walk through how to implement both of your requirements for your AVPlayer-based app. I'll tie everything to your existing AVPlayerViewController setup so it fits right in.

First, you'll use the flag from your backend to toggle seek functionality. Here's a reliable approach that gives you full control:

Step 1: Track the Restriction Flag #

Add properties to your view controller to track if seeking is allowed, plus another to keep the last valid playback time (to block unwanted seeks):

@property (nonatomic, assign) BOOL allowsSeek;
@property (nonatomic, assign) CMTime lastValidPlaybackTime;

Step 2: Configure Controls Based on the Flag #

When you receive video data from your backend, use the restriction flag to set up the player:

// Assume `isSeekRestricted` is the boolean flag from your backend response
self.allowsSeek = !isSeekRestricted;

if (!self.allowsSeek) {
    // Hide system controls to disable the default progress bar
    self.videoPlayerViewController.showsPlaybackControls = NO;
    
    // Add a custom play/pause button (adjust frame and styling as needed)
    UIButton *playPauseBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 60, 60)];
    playPauseBtn.center = self.videoPlayerViewController.view.center;
    playPauseBtn.tag = 100; // Use a tag to reference it later
    [playPauseBtn setImage:[UIImage systemImageNamed:@"play.fill"] forState:UIControlStateNormal];
    [playPauseBtn setImage:[UIImage systemImageNamed:@"pause.fill"] forState:UIControlStateSelected];
    [playPauseBtn addTarget:self action:@selector(togglePlayPause:) forControlEvents:UIControlEventTouchUpInside];
    [self.videoPlayerViewController.view addSubview:playPauseBtn];
    
    // Listen to playback status to update the button state
    [self.videoPlayerViewController.player addObserver:self forKeyPath:@"timeControlStatus" options:NSKeyValueObservingOptionNew context:nil];
    
    // Track initial playback time to block unwanted seeks
    self.lastValidPlaybackTime = self.videoPlayerViewController.player.currentItem.currentTime;
    [self.videoPlayerViewController.player.currentItem addObserver:self forKeyPath:@"currentTime" options:NSKeyValueObservingOptionNew context:nil];
} else {
    // Re-enable system controls for unrestricted videos
    self.videoPlayerViewController.showsPlaybackControls = YES;
    
    // Clean up observers if they were added previously
    [self.videoPlayerViewController.player removeObserver:self forKeyPath:@"timeControlStatus"];
    if (self.videoPlayerViewController.player.currentItem) {
        [self.videoPlayerViewController.player.currentItem removeObserver:self forKeyPath:@"currentTime"];
    }
}

Step 3: Handle KVO Observations and Play/Pause #

Implement the observer method to enforce the seek restriction and update the play/pause button:

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
    if ([keyPath isEqualToString:@"timeControlStatus"]) {
        // Update play/pause button based on current playback state
        AVPlayerTimeControlStatus status = [change[NSKeyValueChangeNewKey] integerValue];
        UIButton *playPauseBtn = [self.videoPlayerViewController.view viewWithTag:100];
        playPauseBtn.selected = (status == AVPlayerTimeControlStatusPlaying);
    } else if ([keyPath isEqualToString:@"currentTime"]) {
        if (!self.allowsSeek) {
            CMTime newTime = [change[NSKeyValueChangeNewKey] CMTimeValue];
            // If time changed unexpectedly (user tried to seek), reset to last valid time
            if (CMTimeCompare(newTime, self.lastValidPlaybackTime) != 0) {
                [self.videoPlayerViewController.player seekToTime:self.lastValidPlaybackTime toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];
            } else {
                // Update valid time as video plays normally
                self.lastValidPlaybackTime = newTime;
            }
        }
    }
}

- (void)togglePlayPause:(UIButton *)sender {
    sender.selected = !sender.selected;
    if (sender.selected) {
        [self.videoPlayerViewController.player play];
    } else {
        [self.videoPlayerViewController.player pause];
    }
}

To get notified when a video completes, use AVPlayer's built-in notification system:

Step 1: Add a Notification Observer #

When setting up your AVPlayerItem, register for the finish notification:

// Assume `videoURLString` is the URL from your backend
NSURL *videoURL = [NSURL URLWithString:videoURLString];
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithURL:videoURL];

// Register for the finish notification
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(videoDidFinishPlaying:)
                                             name:AVPlayerItemDidPlayToEndTimeNotification
                                           object:playerItem];

// Assign the item to your player
self.videoPlayerViewController.player = [AVPlayer playerWithPlayerItem:playerItem];

Step 2: Handle the Finish Event #

Implement the selector to capture the finish time and handle post-playback actions:

- (void)videoDidFinishPlaying:(NSNotification *)notification {
    AVPlayerItem *finishedItem = notification.object;
    
    // Get current system time as the finish time
    NSDate *finishTime = [NSDate date];
    NSLog(@"Video completed at %@", finishTime);
    
    // Add your logic here: e.g., report to backend, play next video, etc.
    
    // Clean up observer to avoid memory leaks
    [[NSNotificationCenter defaultCenter] removeObserver:self name:AVPlayerItemDidPlayToEndTimeNotification object:finishedItem];
}

Step 3: Clean Up Observers #

Don't forget to remove all observers in your view controller's dealloc method to prevent memory leaks:

- (void)dealloc {
    [self.videoPlayerViewController.player removeObserver:self forKeyPath:@"timeControlStatus"];
    if (self.videoPlayerViewController.player.currentItem) {
        [self.videoPlayerViewController.player.currentItem removeObserver:self forKeyPath:@"currentTime"];
        [[NSNotificationCenter defaultCenter] removeObserver:self name:AVPlayerItemDidPlayToEndTimeNotification object:self.videoPlayerViewController.player.currentItem];
    }
}

内容的提问来源于stack exchange，提问作者Keshav.K