private Dictionary<char, int> DoFindControlChars(NSString str)
{
var chars = new Dictionary<char, int>();
int len = (int) str.length();
NSRange range = new NSRange(0, len);
while (true)
{
NSRange temp = str.rangeOfCharacterFromSet_options_range(
NSCharacterSet.controlCharacterSet(),
Enums.NSLiteralSearch,
range);
if (temp.length == 0)
break;
char ch = str.characterAtIndex((uint) temp.location);
if (ch != '\r' && ch != '\n' && ch != '\t' && ch != Constants.BOM[0])
{
if (chars.ContainsKey(ch))
chars[ch] = chars[ch] + 1;
else
chars[ch] = 1;
}
range = new NSRange(temp.location + 1, len - (temp.location + 1));
}
return chars;
}