Question

This code works well:

UIDatePicker *pickerView = [[UIDatePicker alloc] initWithFrame:pickerFrame];
[pickerView addTarget:self 
               action:@selector(pickerChanged:) 
     forControlEvents:UIControlEventValueChanged];
[self.view addSubview:pickerView];

Why i don’t need to add pickers controller to my UIViewControllers hierarchy?

[self addChildViewController:pickerView.controller];

I know, UIView has no controller property. But how UIPIcker component adds his controller to controllers hierarchy? Or UIPicker have no controller at all? Or this controller don’t need to be in controllers hierarchy?

I need to know this to develop my own custom UI components, that should should be easy to integrate.

Answer 1

UIDatePicker is a subclass of UIControl that is a subclass of UIView
So its not a UIViewController, adding UIView to the views is adding using addSubView

If UIDatePicker was a subclass of UIViewController then indeed you would have to add it using addChildViewController

When you create your custom views its your coice, it will depend on what class you extend, if you extend UIView then you will need to use addSubView, if it will extend UIViewController then use addChildViewController