TextField Validation With Regular Expression

Question

I need help with code that looks at a textfield make sure it starts with either a (+ or -) then has 3 integers after it.

So valid data looks like +234 or -888

Answer 1

Validate Email id or Phone number using Regular Expression

Ddelegate methods:

- (BOOL)textFieldShouldReturn:(UITextField *)aTextField
{
    [aTextField resignFirstResponder];
    return YES;
}

- (BOOL)textFieldShouldEndEditing:(UITextField *)aTextField
{
    return [self validateEmail:aTextField.text]; // Change validateEmail to validatePhone for phone validation.
}

Returns YES or NO whether the input is valid or not:

- (BOOL) validateEmail: (NSString *) candidate {
    NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"; 
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex]; 

    return [emailTest evaluateWithObject:candidate];
}

- (BOOL) validatePhone: (NSString *) candidate {
    NSString *phoneRegex = @"^+(?:[0-9] ?){6,14}[0-9]$"; 
    NSPredicate *phoneTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", phoneRegex]; 

    return [phoneTest evaluateWithObject:candidate];
}