Check if textfield text is almost equal to string

Question

I have a UITextField called textfield. And I have this code to check if the text in the textfield is equal to "exampletext"

if ([textfield.text isEqualToString:@"exampletext"]) {
    NSLog(@"Correct");
} else {
    NSLog(@"Wrong");
}

But I also want to check if the text in the textfield is almost equal to "exampletext", if the text is almost the same as "exampletext". Like if the text was "eampletex" I want to NSLog(@"Close")

Are there any ways to check if the textfield text is like 50% equal to "exampletext"? Or any ways to check if the textfield text has 50% the same characters as "exampletext"? Or something else like that?

Answer 1

What you are looking for is an implementation of the levenshtein distance, levenshtein("hello", "hallo") => 1, levenshtein("hello", "ellos") => 2. You can check this library.

Once you have the distance between the two strings, you could get it as a percentage calculating: percentage = 100 * levenshtein(original,other) / length(original)

Answer 2

Here's my go at it. Create a custom character set from the string you want to match. Check each character in the texfield.text against that character set, and if the number of matches is close to the number of letters in the string, do something..

NSString *testString = @"wordToCompare";
NSString *textFromTextfield = textfield.text;

//create a custom character set from the word you want to compare to...
NSCharacterSet *characterSetForString = [NSCharacterSet characterSetWithCharactersInString:testString];

//keep track of how many matches...
int numberOfCharsThatMatchSet = 0;

    for (int x = 0; x < [textFromTextField length]; x++) {

        unichar charToCheck = [textFromTextField characterAtIndex:x];

        if ([characterSetForString characterIsMember:charToCheck] == YES) {
            numberOfCharsThatMatchSet++;
        }

        NSLog(@"%d", numberOfCharsThatMatchSet);
    }

         // if the number of matches is the same as the length of the word + or - 2...
    if ((numberOfCharsThatMatchSet > [testString length] - 2 ) && (numberOfCharsThatMatchSet < [testString length] + 2 )) {
        NSLog(@"close match...");
    }

Not sure if this is 100% what you're looking for, but maybe it will help anyway...