I've looked into this and unfortunately the options are either very expensive or bad quality:
Related to this, here is how you can use Google's online TTS (code taken from iPhone SDK - Google TTS and encoding):
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:@"file.mp3"];
NSString *text = @"You are one chromosome away from being a potato.";
NSString *urlString = [NSString stringWithFormat:@"http://www.translate.google.com/translate_tts?tl=en&q=%@",text];
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSMutableURLRequest* request = [[[NSMutableURLRequest alloc] initWithURL:url] autorelease];
[request setValue:@"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1) Gecko/20100101 Firefox/4.0.1" forHTTPHeaderField:@"User-Agent"];
NSURLResponse* response = nil;
NSError* error = nil;
NSData* data = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:&error];
[data writeToFile:path atomically:YES];
AVAudioPlayer *player;
NSError *err;
if ([[NSFileManager defaultManager] fileExistsAtPath:path])
{
player = [[AVAudioPlayer alloc] initWithContentsOfURL:
[NSURL fileURLWithPath:path] error:&err];
player.volume = 0.4f;
[player prepareToPlay];
[player setNumberOfLoops:0];
[player play];
}
The voiceover framework from Apple is private and can only used on for accessibility. At least if you want your application approved. But if you want to use it while you decide on what system to use, here it is:
// Not App Store safe. Only available in real devices.
// See http://arstechnica.com/apple/2010/02/iphone-voiceservices-looking-under-the-hood/
#define RTLD_LAZY 0x1
#define RTLD_NOW 0x2
#define RTLD_LOCAL 0x4
#define RTLD_GLOBAL 0x8
NSObject *voiceSynthesizer;
void *voiceServices;
-(void) say:(NSString*)text {
if (!voiceSynthesizer)
{
NSString *vsLocation = @"/System/Library/PrivateFrameworks/VoiceServices.framework/VoiceServices";
voiceServices = dlopen(vsLocation.UTF8String, RTLD_LAZY);
voiceSynthesizer = [NSClassFromString(@"VSSpeechSynthesizer") new];
}
[voiceSynthesizer performSelector:@selector(startSpeakingString:) withObject:text];
}
