My solution for Speakable

[wzienrgo]

Hi everyone,

I’m just working on this challenge and here is my solution. It seems it works but I’m still not very sure about the NSError part. I just check the brand name to see whether it’s in the list and decide to return the error message or not. I think there should be better ways.

[code]- (NSString *)encodeAsSpeakableString
{
// Create the list of all brands
// Keep the NSDictionary object for reuse
static NSDictionary *brandList = nil;
if (!brandList) {
brandList = @{@“Camry”: @0, @“Nikon”: @1, @“Apple”: @2, @“Ford”: @3, @“Audi”: @4,@“Google”: @5,@“Nike”: @6,@“Amazon”: @7,@“Honda”: @8, @“Mazda”: @9,@“Buick”: @10,@“Fiat”: @11, @“Jeep”: @12, @“Lexus”: @13, @“Volvo”: @14, @“Fuji”: @15, @“Sony”: @16, @“Delta”: @17, @“Focus”: @18, @“Puma”: @19, @“Samsung”: @20, @“Tivo”: @21, @“Halo”: @22, @“Sting”: @23, @“Shrek”: @24, @“Avatar”: @25, @“Shell”: @26, @“Visa”: @27, @“Vogue”: @28, @“Twitter”: @29, @“Lego”: @30, @“Pepsi”: @31, };
}

// Get bytes from the NSData object to convert
unsigned char bytes[8];
[self getBytes:bytes];

// Create a mutable string to store converted speakable strings
NSMutableString *dataToString = [[NSMutableString alloc] init];

for (int i = 0; i < [self length]; i++) {
    unsigned char x = bytes[i] >> 5; // Digit part of the string
    unsigned char w = bytes[i] << 3;
    unsigned char y = w >> 3; // Brand part of the string
    NSArray *key = [brandList allKeysForObject:[NSNumber numberWithUnsignedChar:y]]; // Find the key corresponding to the brand number
    NSString *brand = key[0];
    NSString *digit = [NSString stringWithFormat:@"%d ", x + 2]; // To avoid digit 1 and 0
    
    [dataToString appendString:digit];
    [dataToString appendString:brand];
    // add space except for the last brand
    if (i != [self length] - 1) {
        [dataToString appendString:@" "];
    }
}
return [dataToString copy];

}

• (NSData *)dataWithSpeakableString:(NSString *)string
  error:(NSError **)error
  {
  static NSDictionary *brandList = nil;
  if (!brandList) {
  brandList = @{@“Camry”: @0, @“Nikon”: @1, @“Apple”: @2, @“Ford”: @3, @“Audi”: @4,@“Google”: @5,@“Nike”: @6,@“Amazon”: @7,@“Honda”: @8, @“Mazda”: @9,@“Buick”: @10,@“Fiat”: @11, @“Jeep”: @12, @“Lexus”: @13, @“Volvo”: @14, @“Fuji”: @15, @“Sony”: @16, @“Delta”: @17, @“Focus”: @18, @“Puma”: @19, @“Samsung”: @20, @“Tivo”: @21, @“Halo”: @22, @“Sting”: @23, @“Shrek”: @24, @“Avatar”: @25, @“Shell”: @26, @“Visa”: @27, @“Vogue”: @28, @“Twitter”: @29, @“Lego”: @30, @“Pepsi”: @31, };
  } // Create the list incase it is not created yet

  // Create the character set of 10 digits
  NSCharacterSet *digitSet = [NSCharacterSet decimalDigitCharacterSet];

  NSRange searchRange;
  searchRange.location = 0;
  searchRange.length = [string length];

  unsigned char digits[8]; // Store the digits of the speakable string
  unsigned long digitLocations[8]; // Store the locations of the digits in the speakable string
  // Find the digits one by one and store them in "digits"
  for (int i = 0; i < [string length]; i++) {
  NSRange range = [string rangeOfCharacterFromSet:digitSet
  options:NSLiteralSearch
  range:searchRange];
  if (range.length == 0) {
  break; // Stop the loop if no more digit can be found
  } else {
  int digit = [[string substringWithRange:range] intValue] - 2; // convert the substring of digit to an integer
  digits[i] = (unsigned char)digit; // Store it in a byte of "digits"
  digitLocations[i] = range.location; // Store the location here for future use
  // Define a new range to search for next digit
  searchRange.location = range.location + 1;
  searchRange.length = [string length] - searchRange.location;
  }
  }

  // Now it’s time to convert the brands
  unsigned char brandParts[8]; // Store the number of brands here
  for (int i = 0; i < 8; i++) {
  // Calculate the range of a particular brand
  NSRange brandRange;
  brandRange.location = digitLocations[i] + 2;
  if (i < 7) {
  brandRange.length = digitLocations[i+1] - digitLocations[i] - 3;
  } else {
  brandRange.length = [string length] - brandRange.location;
  }
  NSString *brand = [string substringWithRange:brandRange]; // Get the brand
  NSNumber *brandNumber = [brandList objectForKey:brand];

    // Is the brand string in the brand list?
    if (brandNumber == nil) {
        //Did the user give the address to place error?
        if (error) {
            NSDictionary *userInfo = @{NSLocalizedDescriptionKey: @"Unable to parse!"};
            *error = [NSError errorWithDomain:@"SpeakableBytes"
                                         code:1
                                     userInfo];
            return nil;
        }
        
    }
    
    brandParts[i] = [brandNumber unsignedCharValue];
  

  }

  // Combine the two parts above
  unsigned char bytesFromString[8];
  for (int i = 0; i < 8; i++) {
  bytesFromString[i] = (digits[i] << 5) | brandParts[i];
  }

  // Create an NSData to wrap the bytes
  NSData *Data = [NSData dataWithBytes:&bytesFromString
  length:8 * sizeof(unsigned char)];

  return Data;
  }
  [/code]