Question

im beginner in xcode.
How to code for something that you haven’t yet to complete write information or no value in UILabel (labelDate) and then UIAlertView pop-up to tell you if you haven’t yet input information?

My UILabel get input from code below

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    year = [picker selectedRowInComponent:0];
    month = [picker selectedRowInComponent:1];
    day = [picker selectedRowInComponent:2];
    date = @"";
    if(viewPicker.tag == 1)
        labelDate.text = [date stringByAppendingFormat:@"%d:%d:%d", year , month, day];
    else
    ... etc
}

and my button is like this

- (IBAction)readyBtn:(id)sender { 
    if ( ??? ) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:@"Please input date" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }

I already tried out to write like this but i think it is not good idea because uialertview is popup if year,month,day is choosen to 0.

- (IBAction)readyBtn:(id)sender { 
    if (viewPicker.tag == 1) {
        year = month = day = 0;
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:@"Please input date" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }

thank you for teaching me.

Answer 1

Your Button event would be like this:

 - (IBAction)readyBtn:(id)sender 
 { 
    if ( labelDate.text.length >0 ) // Add OR condition for any other lablel or textField
    {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:@"Please input date" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
    }
}