Counting occurrences of capital letters and numbers in an NSString - objective-c

Question

In PHP I am using the following code...
$passwordCapitalLettersLength = strlen(preg_replace("![^A-Z]+!", "", $password));
$passwordNumbersLength = strlen(preg_replace("/[0-9]/", "", $password));
...to count how many times capital letters and numbers appear in the password.
What is the equivalent of this in Objective C?

Answer 1

You can use the NSCharacterSet:
NSString *password = #"aas2dASDasd1asdASDasdas32D";
int occurrenceCapital = 0;
int occurenceNumbers = 0;
for (int i = 0; i < [password length]; i++) {
if([[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[password characterAtIndex:i]])
occurenceCapital++;
if([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:[password characterAtIndex:i]])
occurenceNumbers++;
}

Answer 2

This can be done fairly concisely using the abilities of NSString and NSCharacterSet, instead of the need to iterate manually.
A decrement of 1 is required as componentsSeparatedByCharactersInSet: will always return at least one element, and that one element won't count your separations.
NSString* password = #"dhdjGHSJD7d56dhHDHa7d5bw3/%£hDJ7hdjs464525";
NSArray* capitalArr = [password componentsSeparatedByCharactersInSet:[NSCharacterSet uppercaseLetterCharacterSet]];
NSLog(#"Number of capital letters: %ld", (unsigned long) capitalArr.count - 1);
NSArray* numericArr = [password componentsSeparatedByCharactersInSet:[NSCharacterSet decimalDigitCharacterSet]];
NSLog(#"Number of numeric digits: %ld", (unsigned long) numericArr.count - 1);
Original answer: Whilst the code you've provided won't cover all bases, if you need to keep using those regular expressions for safety/risk reasons, you can do so below.
You can use RegEx in Objective-C. Saves manually iterating through the String, and keeps the code concise. It also means because you aren't iterating manually, you could potentially get a performance boost, as you can let the compiler/framework writer optimize it.
// Testing string
NSString* password = #"dhdjGHSJD7d56dhHDHa7d5bw3/%£hDJ7hdjs464525";
NSRegularExpression* capitalRegex = [NSRegularExpression regularExpressionWithPattern:#"[A-Z]"
options:0
error:nil];
NSRegularExpression* numbersRegex = [NSRegularExpression regularExpressionWithPattern:#"[0-9]"
options:0
error:nil];
NSLog(#"Number of capital letters: %ld", (unsigned long)[capitalRegex matchesInString:password
options:0
range:NSMakeRange(0, password.length)].count);
NSLog(#"Number of numeric digits: %ld", (unsigned long)[numbersRegex matchesInString:password
options:0
range:NSMakeRange(0, password.length)].count);