播放音频

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

@interface ViewController : UIViewController<AVAudioPlayerDelegate>

@property (weak, nonatomic) IBOutlet UILabel *averageLabel;
@property (weak, nonatomic) IBOutlet UILabel *peakLabel;
@property (weak, nonatomic) IBOutlet UISlider *rateSlider;
@property (weak, nonatomic) IBOutlet UISlider *panSlider;
@property (weak, nonatomic) IBOutlet UISlider *volumeSlider;
@property (strong, nonatomic) AVAudioPlayer *player;

- (IBAction)updateRate:(id)sender;
- (IBAction)updatePan:(id)sender;
- (IBAction)updateVolume:(id)sender;
- (IBAction)playVibrateSound:(id)sender;
- (IBAction)startPlayer:(id)sender;
- (IBAction)pausePlayer:(id)sender;

@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize averageLabel;
@synthesize peakLabel;
@synthesize rateSlider;
@synthesize panSlider;
@synthesize volumeSlider;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    NSString *fileName = @"midnight-ride"; // Change this to your own file
    NSString *fileType = @"mp3";
    NSString *soundFilePath = [[NSBundle mainBundle] pathForResource:fileName ofType:fileType];
    NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];
    
    NSError *error;
    self.player = [[AVAudioPlayer alloc] initWithContentsOfURL:soundFileURL error:&error];
    if (error)
    {
        NSLog(@"Error creating the audio player: %@", error);
    }
    self.player.enableRate = YES; //Allows us to change the playback rate.
    self.player.meteringEnabled = YES; //Allows us to monitor levels
    self.player.delegate = self;
    self.volumeSlider.value = self.player.volume;
    self.rateSlider.value = self.player.rate;
    self.panSlider.value = self.player.pan;
    
    [self.player prepareToPlay]; //Preload audio to decrease lag
    
    [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(updateLabels) userInfo:nil repeats:YES];
}

-(void)updateLabels
{
    [self.player updateMeters];
    self.averageLabel.text = [NSString stringWithFormat:@"%f", [self.player averagePowerForChannel:0]];
    self.peakLabel.text = [NSString stringWithFormat:@"%f", [self.player peakPowerForChannel:0]];
}

- (IBAction)updateRate:(id)sender
{
    self.player.rate = self.rateSlider.value;
}

- (IBAction)updatePan:(id)sender
{
    self.player.pan = self.panSlider.value;
}

- (IBAction)updateVolume:(id)sender
{
    self.player.volume = self.volumeSlider.value;
}

- (IBAction)playVibrateSound:(id)sender
{
    AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
}

- (IBAction)startPlayer:(id)sender
{
    [self.player play];
}

- (IBAction)pausePlayer:(id)sender
{
    [self.player pause];
}

-(void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error
{
    NSLog(@"Error playing file: %@", error);
}

- (void)audioPlayerEndInterruption:(AVAudioPlayer *)player withOptions:(NSUInteger)flags
{
    if (flags == AVAudioSessionInterruptionOptionShouldResume)
    {
        [self.player play];
    }
}