search NSArray with regex - objective-c

Question

I have an array of names. If any of the name is already there then on inserting new name I want to append the counter eg John (02) if John already present in array then John (03) if it is third entry of name John.
Is there any way to filter array with Regex so that I can filter all records with pattern "John (xx)"?

Answer 1

Yup. You have to loop through the array and check with regex. You have to do this, since if you just check if the array contains your string, it won't return true if you search for "John" and the only one in your array is "John1"
NSMutableArray *testArray = [[NSMutableArray alloc] initWithObjects:#"John", #"Steve", #"Alan", #"Brad", nil];
NSString *nameToAdd = #"John";
NSString *regex = [NSString stringWithFormat:#"%#[,]*[0-9]*", nameToAdd];
NSPredicate *myTest = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", regex];
for (int i = 0; i < [testArray count]; i++)
{
NSString *string = [testArray objectAtIndex:i];
if ([myTest evaluateWithObject:string])
{
// Matches
NSLog(#" match !");
int currentValue;
NSArray *split = [string componentsSeparatedByString:#","];
if ([split count] == 1)
{
// Set to 2
currentValue = 2;
}
else
{
currentValue = [[split objectAtIndex:1] intValue];
currentValue++;
}
NSString *newString = [NSString stringWithFormat:#"%#,%d", nameToAdd, currentValue];
[testArray replaceObjectAtIndex:i withObject:newString];
}
}
for (NSString *string in testArray)
{
NSLog(#"%#", string);
}
This will replace "John" with "John,2", and if you search for "John" a third time it will replace it with "John,3".
Hope this helps

Answer 2

You can create a predicate for your regular expression and then filter the array using the predicate. Based on the count of the matches, you can update the new value being added as needed.
NSMutableArray *currentNames = ... // the current list of names
NSString *newName = ... // the new name to add
NSString *regex = [NSString stringWithFormat:#"%# \\([0-9]*\\)", newName];
NSPredicate *filter = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", regex];
NSArray *matches = [currentNames filteredArrayUsingPredicate:filter];
if (matches.count) {
NSString *updatedName = [NSString stringWithFormat:#"%# (%02d)", newName, matches.count];
[currentNames addObject:updatedName];
} else {
[currentNames addObject:newName];
}

Answer 3

You can filer an array with NSPredicate. Not too familiar with regex, but the following seems okay:
NSArray *array = #[#"John (01)", #"John (02)", #"John XX"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF MATCHES 'John [(]\\\\d{2}[)]'"];
NSArray *result = [array filteredArrayUsingPredicate:predicate];
NSLog( #"%#", result ); // Output John (01), John (02)