ios - 如何使用 Obj-C 在 iOS 中播放 mp3

Question

我在 Objective-C 中有一个问题，我正在开发一个 iOS 应用程序，它应该播放特定的 mp3 文件集 -242 个 mp3 文件，所以有人可以告诉我播放它们的最佳方式是什么，我意思是我应该把它们放在服务器上，让它们都在本地还是什么？以及我应该如何在 Xcode 中对它们进行编码。

Answer 1

Apple provide many ways to play audio on the iPhone – System Sound Services, AVAudioPlayer, Audio Queue Services, and OpenAL. Without outside support libraries, the two easiest ways by far are System Sound Services and AVAudioPlayer.

系统声音服务

它对于音频警报和简单的游戏声音很有用。

NSString *pewPewPath = [[NSBundle mainBundle] 
pathForResource:@"pew-pew-lei" ofType:@"caf"];
NSURL *pewPewURL = [NSURL fileURLWithPath:pewPewPath];
AudioServicesCreateSystemSoundID((__bridge CFURLRef)pewPewURL,  
&self.pewPewSound);
AudioServicesPlaySystemSound(self.pewPewSound);

It is important to define pewPewSound as an iVar or property, and not as a local variable so that you can dispose of it later in dealloc. It is declared as a SystemSoundID. If you were to dispose of it immediately after AudioServicesPlaySystemSound(self.pewPewSound), then the sound would never play.

2. AVAudioPlayer

它允许一次播放多个声音(对每个声音使用不同的 AVAudioPlayer)，即使您的应用程序在后台，您也可以播放声音。. AVAudioPlayer 类是 AVFoundation 的一部分，您需要将 AVFoundation @import 到您的项目。

 NSError *error;
self.backgroundMusicPlayer = [[AVAudioPlayer alloc]
initWithContentsOfURL:backgroundMusicURL error:&error];
[self.backgroundMusicPlayer prepareToPlay];
[self.backgroundMusicPlayer play];

ATBViewController.h

#import <UIKit/UIKit.h>

@interface ATBViewController : UIViewController

@end

ATBViewController.m

#import "ATBViewController.h"
#import "AudioController.h"

@interface ATBViewController ()

@property (strong, nonatomic) AudioController *audioController;

@end

@implementation ATBViewController

#pragma mark - Lifecycle

- (void)viewDidLoad {
    [super viewDidLoad];

    self.audioController = [[AudioController alloc] init];
    [self.audioController tryPlayMusic];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - IBAction

- (IBAction)spaceshipTapped:(id)sender {
    //The call below uses AudioServicesPlaySystemSound to play
    //the short pew-pew sound.
    [self.audioController playSystemSound];
    [self fireBullet];
}

- (void)fireBullet {
    // In IB, the button to top layout guide constraint is set to 229, so
    // the bullets appear in the correct place, on both 3.5" and 4" screens
    UIImageView *bullets = [[UIImageView alloc] initWithFrame:CGRectMake(84, 256, 147, 29)];
    bullets.image = [UIImage imageNamed:@"bullets.png"];
    [self.view addSubview:bullets];
    [self.view sendSubviewToBack:bullets];
    [UIView beginAnimations:@"shoot" context:(__bridge void *)(bullets)];
    CGRect frame = bullets.frame;
    frame.origin.y = -29;
    bullets.frame = frame;
    [UIView setAnimationDuration:0.5];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];
    [UIView commitAnimations];
}

- (void) animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
    UIImageView *bullets = (__bridge UIImageView *)context;
    [bullets removeFromSuperview];
}

@end

AudioController.h

#import <Foundation/Foundation.h>

@interface AudioController : NSObject

- (instancetype)init;
- (void)tryPlayMusic;
- (void)playSystemSound;

@end

AudioController.m

#import "AudioController.h"
@import AVFoundation;

@interface AudioController () <AVAudioPlayerDelegate>

@property (strong, nonatomic) AVAudioSession *audioSession;
@property (strong, nonatomic) AVAudioPlayer *backgroundMusicPlayer;
@property (assign) BOOL backgroundMusicPlaying;
@property (assign) BOOL backgroundMusicInterrupted;
@property (assign) SystemSoundID pewPewSound;

@end

@implementation AudioController

#pragma mark - Public

- (instancetype)init
{
    self = [super init];
    if (self) {
        [self configureAudioSession];
        [self configureAudioPlayer];
        [self configureSystemSound];
    }
    return self;
}

- (void)tryPlayMusic {
    // If background music or other music is already playing, nothing more to do here
    if (self.backgroundMusicPlaying || [self.audioSession isOtherAudioPlaying]) {
        return;
    }

       [self.backgroundMusicPlayer prepareToPlay];
    [self.backgroundMusicPlayer play];
     self.backgroundMusicPlaying = YES;
}

- (void)playSystemSound {
    AudioServicesPlaySystemSound(self.pewPewSound);
}

#pragma mark - Private

- (void) configureAudioSession {
    // Implicit initialization of audio session
    self.audioSession = [AVAudioSession sharedInstance];


    NSError *setCategoryError = nil;
    if ([self.audioSession isOtherAudioPlaying]) { // mix sound effects with music already playing
        [self.audioSession setCategory:AVAudioSessionCategorySoloAmbient error:&setCategoryError];
        self.backgroundMusicPlaying = NO;
    } else {
        [self.audioSession setCategory:AVAudioSessionCategoryAmbient error:&setCategoryError];
    }
    if (setCategoryError) {
        NSLog(@"Error setting category! %ld", (long)[setCategoryError code]);
    }
}

- (void)configureAudioPlayer {
    // Create audio player with background music
    NSString *backgroundMusicPath = [[NSBundle mainBundle] pathForResource:@"background-music-aac" ofType:@"caf"];
    NSURL *backgroundMusicURL = [NSURL fileURLWithPath:backgroundMusicPath];
    self.backgroundMusicPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:backgroundMusicURL error:nil];
    self.backgroundMusicPlayer.delegate = self;  // We need this so we can restart after interruptions
    self.backgroundMusicPlayer.numberOfLoops = -1;  // Negative number means loop forever
}

- (void)configureSystemSound {

    NSString *pewPewPath = [[NSBundle mainBundle] pathForResource:@"pew-pew-lei" ofType:@"caf"];
    NSURL *pewPewURL = [NSURL fileURLWithPath:pewPewPath];
    AudioServicesCreateSystemSoundID((__bridge CFURLRef)pewPewURL, &_pewPewSound);
}

#pragma mark - AVAudioPlayerDelegate methods

- (void) audioPlayerBeginInterruption: (AVAudioPlayer *) player {
        self.backgroundMusicInterrupted = YES;
    self.backgroundMusicPlaying = NO;
}

- (void) audioPlayerEndInterruption: (AVAudioPlayer *) player withOptions:(NSUInteger) flags{

      [self tryPlayMusic];
      self.backgroundMusicInterrupted = NO;
}

@end