textField validation on real time in objective-C - ios

Question

I have a TextField in xCode and someone ask me to admit just certain types of characters giving me this text string:
^([A-ZÑÑÁÉÍÓÚÀÈÌÒÙÄËÏÖÜ ])*$
or this one:
^([0-9])*$
I Know a method using UITextFieldDelegate named textField shouldChangeCharactersInRange and this is the way I implement this method:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSString *allowedCharacters = #"abcdefghijklmnñopqrstuvwxyzABCDEFGHIJKLMÑNOPQRSTUVWXYZ0123456789.#-_ ";
NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:allowedCharacters];
if ([string stringByTrimmingCharactersInSet:characterSet].length == 0)textField.text = [textField.text stringByReplacingCharactersInRange:range withString:string];
return NO;
return YES;
}
if you see, on my programming my variable allowedCharacters stores all my valid characters but is in a different format (I have to write all the allowed characters),
I want to program something similar but with my partner's text format ^([0-9])*$ (text using ranges) how do I do that
Thanks in advance

Answer 1

you can use this:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
// Valida el patron que se introduce en el campo de texto
if (![self validateString:string withPattern:#"^([A-Z0-9.#-_ ])*$"]) return NO;
return YES;
}
in the withPattern parameter insert your regex expression, and then here it is the method which does all the magic:
- (BOOL)validateString:(NSString *)string withPattern:(NSString *)pattern
{
NSError *error = nil;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:NSRegularExpressionCaseInsensitive error:&error];
NSAssert(regex, #"Unable to create regular expression");
NSRange textRange = NSMakeRange(0, string.length);
NSRange matchRange = [regex rangeOfFirstMatchInString:string options:NSMatchingReportProgress range:textRange];
BOOL didValidate = NO;
// Did we find a matching range
if (matchRange.location != NSNotFound) didValidate = YES;
return didValidate;
}
test it and tell us how did it go