I did this and seems to work well for me.. hope it helps!
NSString *cleanedHaystack = [haystack stringByReplacingOccurrencesOfString:@"ı"
withString:@"i"];
cleanedHaystack = [cleanedHaystack stringByReplacingOccurrencesOfString:@"İ"
withString:@"I"];
NSString *cleanedNeedle = [needle stringByReplacingOccurrencesOfString:@"ı"
withString:@"i"];
cleanedNeedle = [cleanedNeedle stringByReplacingOccurrencesOfString:@"İ"
withString:@"I"];
NSUInteger options = (NSDiacriticInsensitiveSearch |
NSCaseInsensitiveSearch |
NSWidthInsensitiveSearch);
NSRange range = [cleanedHaystack rangeOfString:cleanedNeedle
options:options];