Hakawai transformer example

hkw_transformer.m

// Text transformer (palindrome)
[self.textView transformSelectedTextWithTransformer:^NSAttributedString *(NSAttributedString *input) {
    NSString *rawInput = [input string];
    NSMutableString *buffer = [NSMutableString string];
    unichar stackC;
    for (NSInteger i=[rawInput length] - 1; i>=0; i--) {
        stackC = [rawInput characterAtIndex:i];
        [buffer appendString:[NSString stringWithCharacters:&stackC length:1]];
    }
    NSDictionary *attrs = [input attributesAtIndex:0 effectiveRange:NULL];
    return [[NSAttributedString alloc] initWithString:buffer attributes:attrs];
}];