Wave Header (Audio)

NSData+Wav.h

@interface NSData (Wav)
- (NSData*) waveData;
@end

NSData+Wav.mm

@implementation NSData (Wav)

- (NSData*) waveData {
    
    NSMutableData *wavData = [NSMutableData data];
    static constexpr char wavFormat[] =
    "fmt "              // field name
    "\x10\x00\x00\x00"  // field size (16 bytes)
    "\x01\x00"          // format tag (PCM)
    "\x01\x00"          // # of channels (1)
    "\x80\x3e\x00\x00"  // sample rate (16,000)
    "\x00\x7d\x00\x00"  // bytes per second (32,000)
    "\x02\x00"          // block alignment (2)
    "\x10\x00";         // bits per sample (16)
    
    auto dataSizeInBytes = 2*(self.length);
    auto totalSizeInBytes = dataSizeInBytes + 36;
    char wavPreamble[] = "RIFF@@@@WAVE";
    wavPreamble[4] = static_cast<unsigned char>(totalSizeInBytes >> 0 );
    wavPreamble[5] = static_cast<unsigned char>(totalSizeInBytes >> 8 );
    wavPreamble[6] = static_cast<unsigned char>(totalSizeInBytes >> 16);
    wavPreamble[7] = static_cast<unsigned char>(totalSizeInBytes >> 24);
    char dataHeader[] = "data@@@@";
    dataHeader[4] = static_cast<unsigned char>(dataSizeInBytes >> 0 );
    dataHeader[5] = static_cast<unsigned char>(dataSizeInBytes >> 8 );
    dataHeader[6] = static_cast<unsigned char>(dataSizeInBytes >> 16);
    dataHeader[7] = static_cast<unsigned char>(dataSizeInBytes >> 24);
    
    [wavData appendBytes:wavPreamble length:12];
    [wavData appendBytes:wavFormat length: 24];
    [wavData appendBytes:dataHeader length:8];
    [wavData appendData:self];
    return [wavData copy];
}
@end