Sequential validation on password text Field - iphone

Question

How can I validate password for sequential value?
Eg -
if user enters 1326 or "axdf" in password then it is valid.
if use enter 1234 or "abcd" the it is invalid.

Answer 1

I think you can do it this way
NSString *list= #"abcdefghijklmnopqrstuvwxyz";
NSString *password= #"abz"; // Suppose this is your password
NSRange range = [list rangeOfString:password options:NSCaseInsensitiveSearch];
if (range.location == NSNotFound) {
/* Could NOT find password in list, then it is valid */
}
else {
/* Found the password in the list then it is not valid */
}
Similarly you can do it for numbers as well

Answer 2

the easiest way is to use strpos.
$haystack = '01234567890';
function testConsecutive($pHaystack, $pNeedle){
return strpos($pHaystack,$pNeedle) === false?false:true;
}
Oops, I thought that I was answering php code, because that was my filter. This is not php, sorry for that.

Answer 3

In this case, i would suggest you to try matching ASCII value of each character in the string. If the string is sequential, ASCII value of that character should increase by 1
Here is a rough idea how you can implement it, havent tested it but hope it might be helpful.
int prevAsciiCode;
NSString *string = #"12345";
for (int i = 0; i<string.length; i++) {
int asciiCode = [string characterAtIndex:i];
if (asciiCode == prevAsciiCode+1) {
NSLog(#"String invalid");
return;
}
prevAsciiCode = asciiCode;
}

Answer 4

A string is a sequence of chars, each char is represented by is ASCII code, so you can iterate throw the chars of the string and compare each one with its previous int value, for example:
- (BOOL)isSequence:(NSString *)string
{
char previousChar = [string characterAtIndex:0];
int wordLength = [string length];
BOOL isSequence = YES;
for (int i = 0; i < wordLength && isSequence; i++)
{
char currentChar = [string characterAtIndex:i];
if (currentChar != previousChar+1) {
isSequence = NO;
}
previousChar = currentChar;
}
return isSequence;
}