Check if NSString contains alphanumeric + underscore characters only

Question

I\'ve got a string that needs to be only a-z, 0-9 and _

How do I check if the input is valid? I\'ve tried this but it accepts letter like å,ä,ö,ø etc.

NS         


        

Answer 1

You can use a predicate:

NSString *myRegex = @"[A-Z0-9a-z_]*"; 
NSPredicate *myTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", myRegex]; 
NSString *string = nameField.text;
BOOL valid = [myTest evaluateWithObject:string];

Edit: I don't noticed that you are using [NSString stringWithString:nameField.text].

Use nameField.text instead.