Question

How can i change number Of Rows In each Components
i have this:

- (NSInteger) pickerView:(UIPickerView *)pickerView  numberOfRowsInComponent:(NSInteger)component
{
return 3;
}

BUT this change all of Components rows number,

And The next question is : How can i Change the values in third component Like UIDatePicker : for example: in Date (in january) days are 31 but (in February) days are (29/28) an the third components must change and values will be between 1-29 or 1-28.

Answer 1

Every picker calls -pickerView:numberOfRowsInComponent: and asks it for the number of rows for each component. So this method is called three times, because you have three components. Thus you need to return different values for the components. You get an NSInteger in the component variable to indicate which component is asked for:

- (NSInteger) pickerView:(UIPickerView *)pickerView  numberOfRowsInComponent:(NSInteger)component
{
    switch(component) 
    {
        case 0: // first component has 42 rows
            return 42;
        case 1: // second component has 21 rows
            return 21;
        case 2: // third component has only two rows
            return 2;
    }
}