如何使用MonoTouch在iPhone上播放声音？

Question

I am looking for something like

PlaySound (uint frequency)

Does it exist?

Answer 1

From the HowTo at: http://wiki.monotouch.net/HowTo/Sound/Play_a_Sound_or_Alert

var sound = SystemSound.FromFile (new NSUrl ("File.caf"));  
sound.PlaySystemSound (); 

Answer 2

I don't know about mono, but in the iPhone SDK it isn't easy that easy to create and play sound. Other alternatives are to provide the sound as a file and play that, or create an array representing a sinusoid, and wrap it in a audio wrapper, and pass it to one of many sound APIs.

If mono proves to be just as limited, then search stackoverflow.com for System Sound Services and AVAudioPlayer as starting points.

Here are two ways to play a sound file:

SoundEffect.c (based on Apple's)

#import "SoundEffect.h"

@implementation SoundEffect
+ (id)soundEffectWithContentsOfFile:(NSString *)aPath {
    if (aPath) {
        return [[[SoundEffect alloc] initWithContentsOfFile:aPath] autorelease];
    }
    return nil;
}

- (id)initWithContentsOfFile:(NSString *)path {
    self = [super init];

    if (self != nil) {
        NSURL *aFileURL = [NSURL fileURLWithPath:path isDirectory:NO];

        if (aFileURL != nil)  {
            SystemSoundID aSoundID;
            OSStatus error = AudioServicesCreateSystemSoundID((CFURLRef)aFileURL, &aSoundID);

            if (error == kAudioServicesNoError) { // success
                _soundID = aSoundID;
            } else {
                NSLog(@"Error %d loading sound at path: %@", error, path);
                [self release], self = nil;
            }
        } else {
            NSLog(@"NSURL is nil for path: %@", path);
            [self release], self = nil;
        }
    }
    return self;
}

-(void)dealloc {
    AudioServicesDisposeSystemSoundID(_soundID);
    NSLog(@"Releasing in SoundEffect");

    [super dealloc];
//  self = nil;
}

-(void)play {
    AudioServicesPlaySystemSound(_soundID);
}

-(void)playvibe {
    AudioServicesPlayAlertSound(_soundID);
}
+(void)justvibe {
    AudioServicesPlayAlertSound(kSystemSoundID_Vibrate);
}

@end

SoundEffect.h:

#import <AudioToolbox/AudioServices.h>

@interface SoundEffect : NSObject {
    SystemSoundID _soundID;
}

+ (id)soundEffectWithContentsOfFile:(NSString *)aPath;
- (id)initWithContentsOfFile:(NSString *)path;
- (void)play;
- (void)playvibe;
+ (void)justvibe;
@end

How to use it:

// load the sound
    gameOverSound = [[SoundEffect alloc] initWithContentsOfFile:[mainBundle pathForResource:@"buzz" ofType:@"caf"]];
// play the sound
    [gameOverSound playvibe];

This is useful for when you want to play sound at the same volume as the iPhone's volume control setting, and you won't need to stop or pause the sound.

Another way is:

+ (AVAudioPlayer *) newSoundWithName: (NSString *) name;
{

    NSString *soundFilePath = [[NSBundle mainBundle] pathForResource: name ofType: @"caf"];

    NSURL *fileURL = [[NSURL alloc] initFileURLWithPath: soundFilePath];

    AVAudioPlayer *newPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL: fileURL
                                                                      error: nil];
    [fileURL release];
// if the sound is large and you need to preload it:
    [newPlayer prepareToPlay];
    return (newPlayer);
}

and use it (you can see all the extras when you go with AVAudioPlayer):

timePassingSound = [AVAudioPlayer newSoundWithName:@"ClockTicking"];
[timePassingSound play];    
// change the volume
[timePassingSound volume:0.5];
// pause to keep it at the same place in the sound
[timePassingSound pause];    
// stop to stop completely, and go to beginning
[timePassingSound stop];    
// check to see if sound is still playing
[timePassingSound isPlaying];