What mean of 0x0000000000000000? : I have a view, and remove when there is a situation.

    if (self.superview) {
            
        [self removeFromSuperview]; // breakpoint point here
    }

I `lldb` it :

    (lldb) po self.superview
    0x0000000000000000

How to juedge the `superview` equals to `0x0000000000000000`? 