JSONDecoder objectWithData:error: throws unnecessary exception when data object has zero length.

[tarbayev]

In method:

- (id)objectWithData:(NSData *)jsonData error:(NSError **)error
{
  if(jsonData == NULL) { [NSException raise:NSInvalidArgumentException format:@"The jsonData argument is NULL."]; }
  return([self objectWithUTF8String:(const unsigned char *)[jsonData bytes] length:[jsonData length] error:error]);
}

-[NSData bytes] returns nil, if the length of the receiver is 0.

This causes raising exception in:

- (id)objectWithUTF8String:(const unsigned char *)string length:(NSUInteger)length error:(NSError **)error
{
  if(parseState == NULL) { [NSException raise:NSInternalInconsistencyException format:@"parseState is NULL."];          }
  if(string     == NULL) { [NSException raise:NSInvalidArgumentException       format:@"The string argument is NULL."]; }

  return(_JKParseUTF8String(parseState, NO, string, (size_t)length, error));
}

According to Apple's recommendations, a good practice would be to return nil when string is equal to NULL in second method and raising no exception. This will make behavior more stable.

[hanneshal]

+1 for this solution

[odyth]

Whats doubly frustrating is if you pass in an NSError pointer an exception is still thrown instead of setting the NSError pointer and returning nil.