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过去三天我一直在拔头发来解决这个问题。我检查了很多示例代码，阅读了很多教程，并在 stackoverflow 上搜索并检查了很多很多问题和答案，但我仍然无法解决问题。有几个类似的问题，如 this或 this但他们也没有任何解决方案。
关于我的项目的一点点:
我有一个 NIKMasterViewController 和一个 NIKDetailViewController。在第一个中，我在表格 View 中有一个音频文件列表；选择一行，它导航到 NIKDetailViewController，用户可以在其中查看有关文件的一些信息并播放音频文件。
我在 NIKMasterViewController 中定义了一个 AVAudioPlayer 属性并将其设置为:
NIKMasterViewController.h:
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
NIKMasterViewController.m:
@synthesize audioPlayer;
- (void)prepareForSegue UIStoryboardSegue *)segue senderid)sender
{
if ([[segue identifier] isEqualToString "showDetail"])
{
NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
NIKDetailViewController *detailViewController = (NIKDetailViewController *) segue.destinationViewController;
[detailViewController setAudioPlayer:audioPlayer];
[detailViewController setFeedEntry:[[[self feedParser] feedItems] objectAtIndex:indexPath.row]];
} else {
NSLog(@"Segue Identifier: %@", segue.identifier);
}
}
这就是 NIKMasterViewController 中的 AVAudioPlayer 的全部内容。现在在我的 NIKDetailViewController 我有 AVAudioPlayer 的另一个属性:
NIKDetailViewController.h:
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
现在在我的 .m 文件中，我有一个名为 streamAudio 的方法，该方法在 viewDidLoad 中调用以准备音频播放，并且我有一个 if 条件要求检查 audioPlayer 是否为 nill，如果不是，则 audioPlayer.isPlaying 是否为真，以便 stop 是播放器，但它从未被调用，当我导航回 Master VC 以点击另一行播放另一个文件时，第二个文件开始播放，而第一个文件正在播放，一切都搞混了。
任何帮助都将不胜感激，因为在数小时和数天后无法解决此问题后，我几乎要停止编程了!
NIKDetailViewController.m:
@synthesize audioPlayer;
- (id)initWithNibNameNSString *)nibNameOrNil bundleNSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
selectedItem = [[NSString alloc]init];
}
return self;
}
#pragma mark - Managing the Audio Playback
- (IBAction)togglePlayingStateid)button
{
//Handle the button pressing
[self togglePlayPause];
}
- (void)playAudio
{
//Play the audio and set the button to represent the audio is playing
[audioPlayer play];
[playPauseButton setImage:[UIImage imageNamed"player_pause"] forState:UIControlStateNormal];
}
- (void)pauseAudio
{
//Pause the audio and set the button to represent the audio is paused
[audioPlayer pause];
[playPauseButton setImage:[UIImage imageNamed"player_play"] forState:UIControlStateNormal];
}
- (void)togglePlayPause
{
//Toggle if the music is playing or paused
if (!audioPlayer.playing)
{
[self playAudio];
}
else if (audioPlayer.playing)
{
[self pauseAudio];
}
}
- (void)streamAudio
{
currentFileName = [[feedEntry podcastDownloadURL] lastPathComponent];
NSString* documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString* path = [documentPath stringByAppendingPathComponent:currentFileName];
NSURL* audioURL = [NSURL fileURLWithPath: path];
if (audioPlayer != nil)
{
if (audioPlayer.isPlaying)
{
[audioPlayer stop]; //THIS IS NEVER CALLED
}
audioPlayer = nil; //THIS IS NEVER CALLED
}
audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:audioURL error:nil];
// Set a timer which keep getting the current music time and update the UISlider in 1 sec interval
playbackTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selectorselector(updateSlider) userInfo:nil repeats:YES];
// Set the maximum value of the UISlider
seekSlider.maximumValue = audioPlayer.duration;
currentTime.text = [NSString stringWithFormat"%d:%02d", (int)audioPlayer.currentTime / 60, (int)audioPlayer.currentTime % 60, nil];
remainingTime.text = [NSString stringWithFormat"%d:%02d", (int)(audioPlayer.duration - audioPlayer.currentTime) / 60, (int)(audioPlayer.duration - audioPlayer.currentTime) % 60, nil];
// Set the valueChanged target
[seekSlider addTarget:self actionselector(sliderChanged forControlEvents:UIControlEventValueChanged];
audioPlayer.delegate = self;
[audioPlayer prepareToPlay]; //Add the audio to the memory.
}
- (void)updateSlider
{
// Update the slider about the music time
seekSlider.value = audioPlayer.currentTime;
}
- (IBAction)sliderChangedUISlider *)sender {
// Fast skip the music when user scrolls the slider
[audioPlayer stop];
[audioPlayer setCurrentTime:seekSlider.value];
audioPlayer.delegate = self;
[audioPlayer prepareToPlay];
[audioPlayer play];
}
// Stop the timer when the music is finished (Need to implement the AVAudioPlayerDelegate in the Controller header)
- (void)audioPlayerDidFinishPlayingAVAudioPlayer *)player successfullyBOOL)flag {
// Music completed
if (flag) {
[playbackTimer invalidate];
}
}
- (IBAction)forwardAudioid)sender
{
int currentTime = [audioPlayer currentTime];
[audioPlayer setCurrentTime:currentTime+10];
}
- (IBAction)rewindAudioid)sender
{
int currentTime = [audioPlayer currentTime];
[audioPlayer setCurrentTime:currentTime-10];
}
//Make sure we can recieve remote control events
- (BOOL)canBecomeFirstResponder {
return YES;
}
- (void)remoteControlReceivedWithEvent:(UIEvent *)event {
//if it is a remote control event handle it correctly
if (event.type == UIEventTypeRemoteControl) {
if (event.subtype == UIEventSubtypeRemoteControlPlay) {
[self playAudio];
} else if (event.subtype == UIEventSubtypeRemoteControlPause) {
[self pauseAudio];
} else if (event.subtype == UIEventSubtypeRemoteControlTogglePlayPause) {
[self togglePlayPause];
}
}
}
#pragma mark - view life cycle
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
//Once the view has loaded then we can register to begin recieving controls and we can become the first responder
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[self becomeFirstResponder];
}
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
//End recieving events
[[UIApplication sharedApplication] endReceivingRemoteControlEvents];
[self resignFirstResponder];
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self streamAudio];
//Make sure the system follows our playback status - to support the playback when the app enters the background mode.
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
[[AVAudioSession sharedInstance] setActive: YES error: nil];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
注意:我已尝试将 Detail VC 中的属性设置为 weak 但随后我收到警告，并且在播放文件之前该属性已释放.
Best Answer-推荐答案
所以...我终于可以通过创建 audioplayer 的 singleton 来解决这个问题。方法如下:
- 首先，我从我的
NIKMasterViewController 类中删除了所有与 audioPlayer 相关的代码，其中包括 audioPlayer 声明并设置它在 prepareForSegue 中。
- 我创建了一个名为
NIKAudioPlayer 的新类。
在 NIKAudioPlayer.h:
#import <Foundation/Foundation.h>
#import <AVFoundation/AVFoundation.h>
@interface NIKAudioPlayer : NSObject <AVAudioPlayerDelegate>
{
AVAudioPlayer *currentPlayer;
}
@property (nonatomic, strong) AVAudioPlayer *currentPlayer;
+(NIKAudioPlayer *) sharedPlayer;
-(void)playURL:(NSURL*)url;
@end
在 NIKAudioPlayer.m:
#import "NIKAudioPlayer.h"
@implementation NIKAudioPlayer
@synthesize currentPlayer;
+(NIKAudioPlayer *) sharedPlayer
{
static NIKAudioPlayer* sharedPlayer;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedPlayer = [[NIKAudioPlayer alloc] init];
});
return sharedPlayer;
}
-(void)playURL:(NSURL*)url
{
[currentPlayer stop];
currentPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];
[currentPlayer prepareToPlay];
}
@end
现在在代码中的其他任何地方(在我的例子中是 NIKDetailViewController)，每当我需要播放音频文件时，我都会从 调用 sharedPlayer >NIKAudioPlayer:
[[NIKPlayer sharedPlayer] playURL:audioURL];
[[NIKPlayer sharedPlayer].currentPlayer prepareToPlay];
简而言之，将 NIKDetailViewController 中的所有 audioPlayer 替换为 [NIKPlayer sharedPlayer].currentPlayer，甚至将其转换并使用它无处不在:
audioPlayer = [NIKPlayer sharedPlayer].currentPlayer
关于ios - AVAudioPlayer 始终为 nill，其 isPlaying 属性始终为 false。播放时文件混合，我们在Stack Overflow上找到一个类似的问题：
https://stackoverflow.com/questions/20164873/
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