Formatting number to Phone number Format as and when you type it in UItextfield

Formatting to Phone number format

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    
    int length = [[self formatNumber:[textField text]] length];
    
    if (length == 10) {
      //  [self textFieldShouldEndEditing:textField];
        if(range.length == 0) {
            return NO;
        }
    }
    
    if (length == 3) {
        NSString *num = [self formatNumber:[textField text]];
        textField.text = [NSString stringWithFormat:@"(%@) ",num];
        if (range.length > 0) {
            [textField setText:[NSString stringWithFormat:@"%@",[num substringToIndex:3]]];
        }
    }
    else if (length == 6) {
        NSString *num = [self formatNumber:[textField text]];
        [textField setText:[NSString stringWithFormat:@"(%@) %@-",[num  substringToIndex:3],[num substringFromIndex:3]]];
        if (range.length > 0) {
            [textField setText:[NSString stringWithFormat:@"(%@) %@",[num substringToIndex:3],[num substringFromIndex:3]]];
        }
    }
   
    
    return YES;
}

- (NSString*)formatNumber:(NSString*)mobileNumber {
    mobileNumber = [mobileNumber stringByReplacingOccurrencesOfString:@"(" withString:@""];
    mobileNumber = [mobileNumber stringByReplacingOccurrencesOfString:@")" withString:@""];
    mobileNumber = [mobileNumber stringByReplacingOccurrencesOfString:@" " withString:@""];
    mobileNumber = [mobileNumber stringByReplacingOccurrencesOfString:@"-" withString:@""];
    mobileNumber = [mobileNumber stringByReplacingOccurrencesOfString:@"+" withString:@""];
    
    int length = [mobileNumber length];
    
    
    
    if (length > 10) {
        mobileNumber = [mobileNumber substringFromIndex: length-10];
    }
    
    return mobileNumber;
}