def extract_key_value(line)
      match = line.match(KEY_VALUE_PATTERN)
      if match
        key = match[1]
        value = match[2]
        [key.strip, value.strip]
      else
        []
      end
    end
def extract_key_value(line)
      match = line.match(KEY_VALUE_PATTERN)
      if match
        key = match[1]
        value = match[2]
        [key.strip, value.strip]
      else
        []
      end
    end
Returns the key and the value described by the given line of an xcconfig.

 @param  [String] line
         the line to process.

 @return [Array] A tuple where the first entry is the key and the second
         entry is the value.