//
// AVQueuePlayerPrevious.m 的类封装的代码
// IntervalPlayer
//
// Created by Daniel Giovannelli on 2/18/13.
//
#import "AVQueuePlayerPrevious.h"
@implementation AVQueuePlayerPrevious
@synthesize itemsForPlayer = _itemsForPlayer;
// CONSTRUCTORS
-(id)initWithItems:(NSArray *)items
{
// This function calls the constructor for AVQueuePlayer, then sets up the nowPlayingIndex to 0 and
// saves the array that the player was generated from as itemsForPlayer
self = [super initWithItems:items];
if (self){
self.itemsForPlayer = [NSMutableArray arrayWithArray:items];
nowPlayingIndex = 0;
isCalledFromPlayPreviousItem = NO;
for (int songPointer = 0; songPointer < [items count]; songPointer++) {
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(songEnded:)
name:AVPlayerItemDidPlayToEndTimeNotification
object:[items objectAtIndex:songPointer]];
}
}
return self;
}
+ (AVQueuePlayerPrevious *)queuePlayerWithItems:(NSArray *)items
{
// This function just allocates space for, creates, and returns an AVQueuePlayerPrevious from an array.
// Honestly I think having it is a bit silly, but since its present in AVQueuePlayer it needs to be
// overridden here to ensure compatability. If anyone has any insight on why this method exists at all,
// let me know.
AVQueuePlayerPrevious *playerToReturn = [[AVQueuePlayerPrevious alloc] initWithItems:items];
return playerToReturn;
}
// NEW METHODS
-(void)songEnded:(NSNotification *)notification {
// This method is called by NSNotificationCenter when a song finishes playing; all it does is increment
// nowPlayingIndex
if (nowPlayingIndex < [_itemsForPlayer count] - 1){
nowPlayingIndex++;
}
}
-(void)playPreviousItem
{
// This function is the meat of this library: it allows for going backwards in an AVQueuePlayer,
// basically by clearing the player and repopulating it from the index of the last song played.
// It should be noted that if the player is on its first song, this function will do nothing. It will
// not restart the song or anything like that; if you want that functionality you can implement it
// yourself fairly easily using the isAtBeginning method to test if the player is at its start.
if (nowPlayingIndex>0){
[self pause];
// Note: it is necessary to have seekToTime called twice in this method, once before and once after re-making the area. If it is not present before, the player will resume from the same spot in the next song when the previous song finishes playing; if it is not present after, the previous song will be played from the same spot that the current song was on.
[self seekToTime:kCMTimeZero toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];
// The next two lines are necessary since RemoveAllItems resets both the nowPlayingIndex and _itemsForPlayer
int tempNowPlayingIndex = nowPlayingIndex;
NSMutableArray *tempPlaylist = [[NSMutableArray alloc]initWithArray:_itemsForPlayer];
[self removeAllItems];
isCalledFromPlayPreviousItem = YES;
for (int i = tempNowPlayingIndex - 1; i < [tempPlaylist count]; i++) {
[self insertItem:[tempPlaylist objectAtIndex:i] afterItem:nil];
}
isCalledFromPlayPreviousItem = NO;
// The temp index is necessary since removeAllItems resets the nowPlayingIndex
nowPlayingIndex = tempNowPlayingIndex - 1;
// Not a typo; see above comment
[self seekToTime:kCMTimeZero toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];
[self play];
}
}
-(Boolean)isAtBeginning
{
// This function simply returns whether or not the AVQueuePlayerPrevious is at the first song. This is
// useful for implementing custom behavior if the user tries to play a previous song at the start of
// the queue (such as restarting the song).
if (nowPlayingIndex == 0){
return YES;
} else {
return NO;
}
}
// OVERRIDDEN AVQUEUEPLAYER METHODS
-(void)removeAllItems
{
// This does the same thing as the normal AVQueuePlayer removeAllItems, but also sets the
// nowPlayingIndex to 0.
[super removeAllItems];
nowPlayingIndex = 0;
[_itemsForPlayer removeAllObjects];
}
-(void)removeItem:(AVPlayerItem *)item
{
// This method calls the superclass to remove the items from the AVQueuePlayer itself, then removes
// any instance of the item from the itemsForPlayer array. This mimics the behavior of removeItem on
// AVQueuePlayer, which removes all instances of the item in question from the queue.
// It also subtracts 1 from the nowPlayingIndex for every time the item shows up in the itemsForPlayer
// array before the current value.
[super removeItem:item];
int appearancesBeforeCurrent = 0;
for (int tracer = 0; tracer < nowPlayingIndex; tracer++){
if ([_itemsForPlayer objectAtIndex:tracer] == item) {
appearancesBeforeCurrent++;
}
}
nowPlayingIndex -= appearancesBeforeCurrent;
[_itemsForPlayer removeObject:item];
}
- (void)advanceToNextItem
{
// The only addition this method makes to AVQueuePlayer is advancing the nowPlayingIndex by 1.
[super advanceToNextItem];
if (nowPlayingIndex < [_itemsForPlayer count] - 1){
nowPlayingIndex++;
}
}
-(void)insertItem:(AVPlayerItem *)item afterItem:(AVPlayerItem *)afterItem
{
// This method calls the superclass to add the new item to the AVQueuePlayer, then adds that item to the
// proper location in the itemsForPlayer array and increments the nowPlayingIndex if necessary.
[super insertItem:item afterItem:afterItem];
if (!isCalledFromPlayPreviousItem){
if ([_itemsForPlayer indexOfObject:item] < nowPlayingIndex)
{
nowPlayingIndex++;
}
}
if ([_itemsForPlayer containsObject:afterItem]){ // AfterItem is non-nil
if ([_itemsForPlayer indexOfObject:afterItem] < [_itemsForPlayer count] - 1){
[_itemsForPlayer insertObject:item atIndex:[_itemsForPlayer indexOfObject:afterItem] + 1];
} else {
[_itemsForPlayer addObject:item];
}
} else { // afterItem is nil
[_itemsForPlayer addObject:item];
}
}
-(int)getIndex
{
// This method simple returns the now playing index
return nowPlayingIndex;
}
@end
