在 iOS 中使用控件播放音频

我制作了一个应用程序tab bar,nav bar and table view.

在表格视图中，您可以选择收听一些音频。

新视图打开，其中有一些控件，例如：播放、暂停、音量滑块、进度滑块、带有当前时间的标签。

它有效，但并不完美。 我可以播放音频，可以暂停音频，还可以使用滑块向前或向后跳。但现在：

当我点击导航栏上的“后退”按钮时，歌曲会继续播放。没关系，但是当我再次返回视图时，计时器和滑块会自行重置。我无法暂停歌曲，只需等待它停止播放。

另外，当我点击播放时，返回表视图，选择另一个要播放的文件，第一个文件不会停止播放.

这是 Audio1DetailViewController.h 代码：

     #import <UIKit/UIKit.h>
     #import <AVFoundation/AVFoundation.h>

     @interface Audio1DetailViewController: UIViewController <AVAudioPlayerDelegate> {

     IBOutlet UISlider *volumeControl; 
     IBOutlet UILabel  *timerLabel; 
     IBOutlet UISlider *progressBar; 

     AVAudioPlayer *audioPlayer;
     NSTimer *playbackTimer; 

     }

     @property (nonatomic, retain) IBOutlet UISlider *volumeControl;
     @property (nonatomic, retain) IBOutlet UILabel *timerLabel;
     @property (nonatomic, retain) IBOutlet UISlider *progressBar;
     @property (nonatomic, retain) NSTimer  *playbackTimer; 
     @property (nonatomic, retain) AVAudioPlayer *audioPlayer;
     -(IBAction) playAudio;
     -(IBAction) stopAudio;
     -(IBAction) adjustVolume;
     -(IBAction) sliderChanged;

     @end

这是 Audio1DetailViewController.m 代码：

     #import "Audio1DetailViewController.h"


     @implementation Audio1DetailViewController

     @synthesize volumeControl, timerLabel, playbackTimer, progressBar, audioPlayer;

     -(void)playAudio
     {
     playbackTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
     target:self
     selector:@selector(updateTime)
     userInfo:nil
     repeats:YES];
     [audioPlayer play];
     }
     -(void)stopAudio
     {
     [playbackTimer invalidate];
     [audioPlayer stop];
     }
     -(void)adjustVolume
     {
     if (audioPlayer != nil)
     {
     audioPlayer.volume = volumeControl.value;
     }
     }

     -(void)updateTime
     {
     float minutes = floor(audioPlayer.currentTime/60);
     float seconds = audioPlayer.currentTime - (minutes * 60);

     float duration_minutes = floor(audioPlayer.duration/60);
     float duration_seconds = 
     audioPlayer.duration - (duration_minutes * 60);

     NSString *timeInfoString = [[NSString alloc] 
     initWithFormat:@"%0.0f.%0.0f / %0.0f.%0.0f",
     minutes, seconds, 
     duration_minutes, duration_seconds];

     timerLabel.text = timeInfoString;
     [timeInfoString release];
     }

     - (void)viewDidLoad {
     [super viewDidLoad];
     NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle]
     pathForResource:@"001Fatiha"
     ofType:@"MP3"]];

     NSError *error;
     audioPlayer = [[AVAudioPlayer alloc]
     initWithContentsOfURL:url
     error:&error];

     [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
     [[AVAudioSession sharedInstance] setActive: YES error: nil];

     if (error)
     {
     NSLog(@"Error in audioPlayer: %@", 
     [error localizedDescription]);
     } else {
     audioPlayer.delegate = self;
     [audioPlayer prepareToPlay];
     }


     playbackTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self
     selector:@selector(updateSlider) userInfo:nil repeats:YES];

     progressBar.maximumValue = audioPlayer.duration;
     // Set the valueChanged target
     [progressBar addTarget:self action:@selector(sliderChanged:) forControlEvents:
     UIControl EventValueChanged];
     }

     - (void)updateSlider {
     // Update the slider about the music time
     progressBar.value = audioPlayer.currentTime;
     }

     - (IBAction)sliderChanged:(UISlider *)sender {
     // Fast skip the music when user scroll the UISlider
     [audioPlayer stop];
     [audioPlayer setCurrentTime:progressBar.value];
     [audioPlayer prepareToPlay];
     [audioPlayer play];
     }

     -(void)audioPlayerDidFinishPlaying:
     (AVAudioPlayer *)player successfully:(BOOL)flag
     {
     }


     -(void)audioPlayerDecodeErrorDidOccur:
     (AVAudioPlayer *)player error:(NSError *)error
     {
     }
     -(void)audioPlayerBeginInterruption:(AVAudioPlayer *)player
     {
     }
     -(void)audioPlayerEndInterruption:(AVAudioPlayer *)player
     {
     }

     -(void)viewDidUnload {
     audioPlayer = nil;
     volumeControl = nil;

     }

     -(void)dealloc {
     [audioPlayer release];
     [volumeControl release];
     [playbackTimer release];
     [super dealloc];
     }

     @end

这是AudioTableViewController.h

     #import <UIKit/UIKit.h>

     @class Audio1DetailViewController;


     @interface AudioTableViewController : UITableViewController 
     <UITableViewDelegate,UITableViewDataSource>{


     IBOutlet UITableView *audioTableView;
     NSMutableArray *audioArray;
     Audio1DetailViewController *audio1DetailViewController;        
     }

     @property (nonatomic, retain) NSMutableArray *audioArray;
     @property (nonatomic, retain) Audio1DetailViewController *audio1DetailViewController;

     @end

和 AudioTableViewController.m

    #import "AudioTableViewController.h"
    #import "Audio1DetailViewController.h"

    #import "DEQAppDelegate.h"

    @implementation AudioTableViewController
    @synthesize audioArray;
    @synthesize audio1DetailViewController;

    - (id)initWithStyle:(UITableViewStyle)style
    {
        self = [super initWithStyle:style];
        if (self) {
            // Custom initialization
    {
        return self;
    }

    - (void)didReceiveMemoryWarning
    {
        // Releases the view if it doesn't have a superview.
        [super didReceiveMemoryWarning];

        // Release any cached data, images, etc that aren't in use.
    }

    #pragma mark - View lifecycle

    - (void)viewDidLoad{
        [super viewDidLoad];
        self.title = NSLocalizedString(@"Audio", @"Audio");
        self.audioArray = [[NSArray alloc] initWithObjects:
                          @"1. Het Begin",  @"2. De Mensen", //etcetera                      
                  nil];
        // Uncomment the following line to preserve selection between presentations.
        self.clearsSelectionOnViewWillAppear = NO;

        // Uncomment the following line to display an Edit button in the navigation bar for this
        view controller.
        // self.navigationItem.rightBarButtonItem = self.editButtonItem;
    }

    - (void)viewDidUnload
    {
        [super viewDidUnload];
        // Release any retained subviews of the main view.
        self.audioArray = nil;
    }

    - (void)viewWillAppear:(BOOL)animated
    {
        [super viewWillAppear:animated];
    }

    - (void)viewDidAppear:(BOOL)animated
    {
        [super viewDidAppear:animated];
    }

    - (void)viewWillDisappear:(BOOL)animated
    {
        [super viewWillDisappear:animated];
    }

    - (void)viewDidDisappear:(BOOL)animated
    {
        [super viewDidDisappear:animated];
    }

    - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
    {
        // Return YES for supported orientations
        return (interfaceOrientation == UIInterfaceOrientationPortrait);
    }

    #pragma mark - Table view data source

    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
    {
    #warning Potentially incomplete method implementation.
        // Return the number of sections.
        return 1;
    }

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
    {
    #warning Incomplete method implementation.
        // Return the number of rows in the section.
        return [self.audioArray count];
    }

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:
      (NSIndexPath *)indexPath
    {
        static NSString *CellIdentifier = @"Cell";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[[UITableViewCell alloc] initWithStyle:
        UITableViewCellStyleDefaultreuseIdentifier:CellIdentifier] autorelease];
        }

        // Configure the cell...
        cell.textLabel.text = [self.audioArray objectAtIndex:[indexPath row]];

        return cell;
    }

    #pragma mark - Table view delegate

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
        // Navigation logic may go here. Create and push another view controller.

        NSUInteger row = indexPath.row;

        if (row == 0) 
        {
     Audio1DetailViewController *audio1DetailViewController =[[Audio1DetailViewController alloc]
     initWithNibName:@"Audio1DetailViewController" bundle:nil]; 
     audio1DetailViewController.title = @"Audio";
     [self.navigationController pushViewController:audio1DetailViewController animated:YES];   
     [audio1DetailViewController release];

        }

        if (row == 1) 
        {
            //etcetera
        }

    }
    - (void)dealloc{
        [audioArray release];
        [super dealloc];
    }

    @end

我建议您创建一个全局玩家对象。因为现在，每次您将此视图推到导航控制器上时，都会创建一个新视图。这也意味着您对前一个玩家没有任何参考（并且无法阻止它）。因此：将 AVAudioPlayer 声明高一级（在表视图中）。现在，当您在其中选择一行时，将其分配给这个新视图（您链接的视图）的属性。

你使用故事板吗？然后你必须实现该方法prepareForSegue:。为情节提要上的 Segue 指定一个标识符（例如showPlayer并检查一下if (segue.identifier isEqualToString:@"showPlayer")).

现在在你的viewDidLoad检查是否audioPlayer为零。如果你

- (void)viewDidLoad
{
    [super viewDidLoad];
    if (audioPlayer == nil)
    {
         // your init (audioplayer =[[AVAudioPlayer ...
    }
    else
    {
         if (audioPlayer.isPlaying)
         {
             // i.e. pause the player or do other stuff
         }
    }
}

希望这对您有帮助。

Also：不要发布代码图像。只需在您的回复中插入代码或将其发布到pastebin.com 等网站并在您的问题中链接该页面即可。这使得其他人更容易做出回应并提出如何更改代码的建议。

回应你的评论： 相关内容应该是：在 AudioTableViewController.h 中:

@property (strong, nonatomic) AVAudioPlayer *audioPlayer;

在 AudioTableViewController.m 中:

@synthesize audioPlayer;
...
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Navigation logic may go here. Create and push another view controller.

    NSUInteger row = indexPath.row;

    if (row == 0) 
    {
        self.audio1DetailViewController =[[Audio1DetailViewController alloc] initWithNibName:@"Audio1DetailViewController" bundle:nil]; 
        self.audio1DetailViewController.title = @"Audio";
        self.audio1DetailViewController.audioPlayer = self.audioPlayer;
        [self.navigationController pushViewController:self.audio1DetailViewController animated:YES];   
        [self.audio1DetailViewController release];
        ...

Audio1DetailViewController.m

- (void)viewDidLoad {
    [super viewDidLoad];
    NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"001Fatiha" ofType:@"MP3"]];

    NSError *error;

    // this is the important part: if we already have something playing, stop it!
    if (audioPlayer != nil)
    {
        [audioPlayer stop];
    }
    // everything else should happen as normal.
    audioPlayer = [[AVAudioPlayer alloc]
               initWithContentsOfURL:url
               error:&error];

    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
    [[AVAudioSession sharedInstance] setActive: YES error: nil];