Question

My custom control has pointers to parent but I don’t know how to free those pointers in destructor.

variables:

{Pointers}
  Form: TForm;
  GeneralPointer: Pointer;
  Frame: ^TImage;

the constructor:

constructor TViOS.Create(var ImageOutput: TImage);
begin
inherited Create;

  Form := TForm(GetParentForm(TControl(ImageOutput)));
  GeneralPointer := Addr(ImageOutput);
  Frame := GeneralPointer;
...

Answer 1

Since you aren’t creating any of the objects in the constructor, you don’t need to Free them in the destructor — just set them to nil.

destructor TViOS.Destroy;
begin
  Form := nil;
  GeneralPointer := nil;
  Frame := nil;
end;