AVARLDelegateDemo/APLViewController.m

/*
 
 
     File: APLViewController.m
 Abstract: ViewController class implementation, defines categories: PlayControl and PlayAsset.
  Version: 1.0
 
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 */
#import <AVFoundation/AVFoundation.h>
#import "APLViewController.h"
#import "APLPlayerView.h"
#import "APLCustomAVARLDelegate.h"
 
/* Asset keys */
NSString * const kPlayableKey       = @"playable";
 
/* PlayerItem keys */
NSString * const kStatusKey         = @"status";
 
/* AVPlayer keys */
NSString * const kRateKey           = @"rate";
NSString * const kCurrentItemKey    = @"currentItem";
 
static void *AVARLDelegateDemoViewControllerRateObservationContext = &AVARLDelegateDemoViewControllerRateObservationContext;
static void *AVARLDelegateDemoViewControllerStatusObservationContext = &AVARLDelegateDemoViewControllerStatusObservationContext;
static void *AVARLDelegateDemoViewControllerCurrentItemObservationContext = &AVARLDelegateDemoViewControllerCurrentItemObservationContext;
 
 
@interface APLViewController ()
{
    BOOL seekToZeroBeforePlay;
    APLCustomAVARLDelegate *delegate;
}
 
@property (retain, nonatomic) IBOutlet APLPlayerView *playView;
@property (strong, nonatomic) IBOutlet UIBarButtonItem *pauseButton;
@property (strong, nonatomic) IBOutlet UIBarButtonItem *playButton;
@property (strong, nonatomic) IBOutlet UIToolbar *toolbar;
 
@property (nonatomic, copy) NSURL* URL;
@property (readwrite, retain, setter=setPlayer:, getter=player) AVPlayer* player;
@property (retain) AVPlayerItem* playerItem;
 
- (IBAction) issuePause:(id)sender;
- (IBAction) issuePlay:(id)sender;
- (void) setupToolbar;
- (void) initializeView;
- (void) viewDidLoad;
- (void) setURL:(NSURL *)URL;
- (void) configDelegates:(AVURLAsset *) asset;
@end
 
/*!
 *  Interface for the play control buttons.
 *  Play
 *  Pause
 */
@interface APLViewController (PlayControl)
- (void) showButton:(id) button;
- (void) showPauseButton;
- (void) showPlayButton;
- (void) syncPlayPauseButtons;
- (void) enablePlayerButtons;
- (void) disablePlayerButtons;
@end
 
/*!
 *  Interface for the AVPlayer
 *  - observe the properties
 *  - initialize the play
 *  - play status
 *  - play failed
 *  - play ended
 */
@interface APLViewController (PlayAsset)
- (void) observeValueForKeyPath:(NSString*) path ofObject:(id)object change:(NSDictionary*)change context:(void*)context;
- (void) prepareToPlayAsset:(AVURLAsset *)asset withKeys:(NSArray *)requestedKeys;
- (BOOL) isPlaying;
- (void) assetFailedToPrepareForPlayback:(NSError *)error;
- (void) playerItemDidReachEnd:(NSNotification *)notification;
@end
 
#pragma mark - APLViewController
 
@implementation APLViewController
 
@synthesize player, playerItem, playView, toolbar, playButton, pauseButton;
 
- (void) setupToolbar
{
    self.toolbar.items = [NSArray arrayWithObjects:self.playButton,  nil];
    [self syncPlayPauseButtons];
}
 
- (void) initializeView
{
    // Restore saved media from the defaults system.
    NSURL *URL = [NSURL URLWithString:@"cplp://devimages.apple.com/samplecode/AVARLDelegateDemo/BipBop_gear3_segmented/redirect_prog_index.m3u8"];
    
    if (URL)
    {
        [self setURL:URL];
    }
}
 
- (void) viewDidLoad
{
    [self setupToolbar];
    [self initializeView];
    [super viewDidLoad];    
}
 
/*!
 *  Create the asset to play (using the given URL).
 *  Configure the asset properties and callbacks when the asset is ready.
 */
- (void) setURL:(NSURL*)URL
{
    if ([self URL] != URL)
    {
        self->_URL = [URL copy];
        
        /*
         Create an asset for inspection of a resource referenced by a given URL.
         Load the values for the asset keys  "playable".
         */
        AVURLAsset *asset = [AVURLAsset URLAssetWithURL:self.URL options:nil];
        [self configDelegates:asset];
        
        NSArray *requestedKeys = [NSArray arrayWithObjects:kPlayableKey, nil];
        
        /* Tells the asset to load the values of any of the specified keys that are not already loaded. */
        [asset loadValuesAsynchronouslyForKeys:requestedKeys completionHandler:
         ^{
             dispatch_async( dispatch_get_main_queue(),
                            ^{
                                /* IMPORTANT: Must dispatch to main queue in order to operate on the AVPlayer and AVPlayerItem. */
                                [self prepareToPlayAsset:asset withKeys:requestedKeys];
                            });
         }];
    }
    
}
 
/*!
 *  Create and setup the custom delegae instance.
 */
- (void) configDelegates:(AVURLAsset*) asset
{
    //Setup the delegate for custom URL.
    self->delegate = [[APLCustomAVARLDelegate alloc] init];
    AVAssetResourceLoader *resourceLoader = asset.resourceLoader;
    [resourceLoader setDelegate:delegate queue:dispatch_queue_create("AVARLDelegateDemo loader", nil)];
    
}
 
/*!
 *  Gets called when the play button is pressed.
 *  Start the playback of the asset and show the pause button.
 */
- (IBAction) issuePlay:(id)sender {
    if (YES == seekToZeroBeforePlay)
    {
        seekToZeroBeforePlay = NO;
        [self.player seekToTime:kCMTimeZero];
    }
    
    [self.player play];
    [self showPauseButton ];
}
 
/*!
 *  Gets called when the pause button is pressed.
 *  Stop the play and show the play button.
 */
- (IBAction) issuePause:(id)sender {
    [self.player pause];
    [self showPlayButton];
}
@end
 
#pragma mark - APLViewController PlayControl
 
@implementation APLViewController (PlayControl)
 
- (void) showButton:(id)button
{
    NSMutableArray *toolbarItems = [NSMutableArray arrayWithArray:[self.toolbar items]];
    [toolbarItems replaceObjectAtIndex:0 withObject:button];
    self.toolbar.items = toolbarItems;
}
 
- (void) showPlayButton
{
    [self showButton:self.playButton];
}
 
- (void) showPauseButton
{
    [self showButton:self.pauseButton];
}
 
- (void) syncPlayPauseButtons
{
    //If we are playing, show the pause button otherwise show the play button
    if ([self isPlaying])
    {
        [self showPauseButton];
    } else
    {
        [self showPlayButton];
    }
}
 
-(void) enablePlayerButtons
{
    self.playButton.enabled = YES;
    self.pauseButton.enabled = YES;
}
 
-(void) disablePlayerButtons
{
    self.playButton.enabled = NO;
    self.pauseButton.enabled = NO;
}
 
@end
 
#pragma mark - APLViewController PlayAsset
 
@implementation APLViewController (PlayAsset)
/*!
 *  Called when the value at the specified key path relative
 *  to the given object has changed.
 *  Adjust the movie play and pause button controls when the
 *  player item "status" value changes. Update the movie
 *  scrubber control when the player item is ready to play.
 *  Adjust the movie scrubber control when the player item
 *  "rate" value changes. For updates of the player
 *  "currentItem" property, set the AVPlayer for which the
 *  player layer displays visual output.
 *  NOTE: this method is invoked on the main queue.
 */
- (void) observeValueForKeyPath:(NSString*) path ofObject:(id)object change:(NSDictionary*)change context:(void*)context
{
    /* AVPlayerItem "status" property value observer. */
    if (context == AVARLDelegateDemoViewControllerStatusObservationContext)
    {
        [self syncPlayPauseButtons];
        
        AVPlayerStatus status = [[change objectForKey:NSKeyValueChangeNewKey] integerValue];
        switch (status)
        {
                /* Indicates that the status of the player is not yet known because
                 it has not tried to load new media resources for playback */
            case AVPlayerStatusUnknown:
            {
                [self disablePlayerButtons];
            }
            break;
                
            case AVPlayerStatusReadyToPlay:
            {
                /* Once the AVPlayerItem becomes ready to play, i.e.
                 [playerItem status] == AVPlayerItemStatusReadyToPlay,
                 its duration can be fetched from the item. */
                
                [self enablePlayerButtons];
            }
            break;
                
            case AVPlayerStatusFailed:
            {
                AVPlayerItem *pItem = (AVPlayerItem *)object;
                [self assetFailedToPrepareForPlayback:pItem.error];
            }
            break;
        }
    }
    /* AVPlayer "rate" property value observer. */
    else if (context == AVARLDelegateDemoViewControllerRateObservationContext)
    {
        [self syncPlayPauseButtons];
    }
    /* 
      AVPlayer "currentItem" property observer.
      Called when the AVPlayer replaceCurrentItemWithPlayerItem:
      replacement will/did occur. 
     */
    else if (context == AVARLDelegateDemoViewControllerCurrentItemObservationContext)
    {
        AVPlayerItem *newPlayerItem = [change objectForKey:NSKeyValueChangeNewKey];
        
        /* Is the new player item null? */
        if (newPlayerItem == (id)[NSNull null])
        {
            [self disablePlayerButtons];
        }
        else /* Replacement of player currentItem has occurred */
        {
            /* Set the AVPlayer for which the player layer displays visual output. */
            [self.playView setPlayer:self.player];
            
            /* Specifies that the player should preserve the video’s aspect ratio and
             fit the video within the layer’s bounds. */
            [self.playView setVideoFillMode:AVLayerVideoGravityResizeAspect];
            
            [self syncPlayPauseButtons];
        }
    }
    else
    {
        [super observeValueForKeyPath:path ofObject:object change:change context:context];
    }
 
}
 
/*!
 *  Invoked at the completion of the loading of the values for all keys on the asset that we require.
 *  Checks whether loading was successfull and whether the asset is playable.
 *  If so, sets up an AVPlayerItem and an AVPlayer to play the asset.
 */
- (void) prepareToPlayAsset:(AVURLAsset *)asset withKeys:(NSArray *)requestedKeys
{
    /* Make sure that the value of each key has loaded successfully. */
    for (NSString *thisKey in requestedKeys)
    {
        NSError *error = nil;
        AVKeyValueStatus keyStatus = [asset statusOfValueForKey:thisKey error:&error];
        if (keyStatus == AVKeyValueStatusFailed)
        {
            [self assetFailedToPrepareForPlayback:error];
            return;
        }
        /* If you are also implementing -[AVAsset cancelLoading], add your code here to bail out properly in the case of cancellation. */
    }
    
    /* Use the AVAsset playable property to detect whether the asset can be played. */
    if (!asset.playable)
    {
        /* Generate an error describing the failure. */
        NSString *localizedDescription = NSLocalizedString(@"Item cannot be played", @"Item cannot be played description");
        NSString *localizedFailureReason = NSLocalizedString(@"The contents of the resource at the specified URL are not playable.", @"Item cannot be played failure reason");
        NSDictionary *errorDict = [NSDictionary dictionaryWithObjectsAndKeys:
                                   localizedDescription, NSLocalizedDescriptionKey,
                                   localizedFailureReason, NSLocalizedFailureReasonErrorKey,
                                   nil];
        NSError *assetCannotBePlayedError = [NSError errorWithDomain:[[NSBundle mainBundle] bundleIdentifier] code:0 userInfo:errorDict];
        
        /* Display the error to the user. */
        [self assetFailedToPrepareForPlayback:assetCannotBePlayedError];
        
        return;
    }
    
    /* At this point we're ready to set up for playback of the asset. */
    
    /* Stop observing our prior AVPlayerItem, if we have one. */
    if (self.playerItem)
    {
        /* Remove existing player item key value observers and notifications. */
        
        [self.playerItem removeObserver:self forKeyPath:kStatusKey];
        
        [[NSNotificationCenter defaultCenter] removeObserver:self
                                                        name:AVPlayerItemDidPlayToEndTimeNotification
                                                      object:self.playerItem];
    }
    
    /* Create a new instance of AVPlayerItem from the now successfully loaded AVAsset. */
    self.playerItem = [AVPlayerItem playerItemWithAsset:asset];
    
    /* Observe the player item "status" key to determine when it is ready to play. */
    [self.playerItem addObserver:self
                       forKeyPath:kStatusKey
                          options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                          context:AVARLDelegateDemoViewControllerStatusObservationContext];
    
    /* When the player item has played to its end time we'll toggle
     the movie controller Pause button to be the Play button */
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(playerItemDidReachEnd:)
                                                 name:AVPlayerItemDidPlayToEndTimeNotification
                                               object:self.playerItem];
    
    seekToZeroBeforePlay = NO;
    
    /* Create new player, if we don't already have one. */
    if (!self.player)
    {
        /* Get a new AVPlayer initialized to play the specified player item. */
        [self setPlayer:[AVPlayer playerWithPlayerItem:self.playerItem]];
        
        /* Observe the AVPlayer "currentItem" property to find out when any
         AVPlayer replaceCurrentItemWithPlayerItem: replacement will/did
         occur.*/
        [self.player addObserver:self
                      forKeyPath:kCurrentItemKey
                         options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                         context:AVARLDelegateDemoViewControllerCurrentItemObservationContext];
        
        /* Observe the AVPlayer "rate" property to update the scrubber control. */
        [self.player addObserver:self
                      forKeyPath:kRateKey
                         options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                         context:AVARLDelegateDemoViewControllerRateObservationContext];
    }
    
    /* Make our new AVPlayerItem the AVPlayer's current item. */
    if (self.player.currentItem != self.playerItem)
    {
        /* Replace the player item with a new player item. The item replacement occurs
         asynchronously; observe the currentItem property to find out when the
         replacement will/did occur*/
        [self.player replaceCurrentItemWithPlayerItem:self.playerItem];
        
        [self syncPlayPauseButtons];
    }
    
}
 
- (BOOL) isPlaying
{
    return [self.player rate] != 0.f;
}
 
/*!
 *  Called when an asset fails to prepare for playback for any of
 *  the following reasons:
 *
 *  1) values of asset keys did not load successfully,
 *  2) the asset keys did load successfully, but the asset is not
 *     playable
 *  3) the item did not become ready to play.
 */
-(void) assetFailedToPrepareForPlayback:(NSError *)error
{
    [self disablePlayerButtons];
    
    /* Display the error. */
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:[error localizedDescription]
                                                        message:[error localizedFailureReason]
                                                       delegate:nil
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil];
    [alertView show];
}
 
/*! 
 *  Called when the player item has played to its end time.
 */
- (void) playerItemDidReachEnd:(NSNotification *)notification
{
    /* After the movie has played to its end time, seek back to time zero
     to play it again. */
    seekToZeroBeforePlay = YES;
}
@end


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