Select component created at runtime - delphi

Question

What I Want to do:
I create on the run a panel, 2 editfield, a radiobox.
When I Click on the RadioButton Edit1 I want to have the Edit1 field visible, and Edit2 filed Not visible
and reverse by the click on the RadioButton Edit2.
But it doesn't work I probably misunderstand something.
Do you have any idea?
procedure CreationPanel(L,T,H,W:integer;Nom,Titre:string
{MyPanel:TPanel});
begin
MyPanel:=TPanel.Create(Form1);
with MyPanel do
begin
Height:=H;
Left:=L;
Width:=W;
Top:=T;
BorderStyle:=bsSingle;
BevelWidth:=3;
BevelOuter:=bvRaised;
Parent:=Form1;
Visible:=True;
TabOrder:=-1;
TabStop:=False;
Tag:=100;
Name:=Nom;
Caption:=Nom;
end;
end;
procedure Creation_Edit(L,T,FontSize:integer;
NomComp,NomPanel:String;
Bool:Boolean
{MyPanel:Tpanel});
begin
MyEdit:=TEdit.Create(MyPanel);
with MyEdit do
begin
Parent:=MyPanel;
{Relation Table Dossier avec Table Bezeichnung}
Height :=21 ;
Left :=L ;
Top :=T ;
Width :=100;
Name:=NomComp;
Font.Name:='MS Sans Serif';
Font.Size:=FontSize;
Visible:=Bool;
end;
end;
procedure Creation_RadioGroup(L,T,H,W,FontSize:integer;
RGName,NomPanel:string
{MyPanelRG:TPanel});
begin
MyRadioGroup:=TRadioGroup.Create(MyPanel);
with MyRadioGroup do
begin
Parent:=MyPanel;
Height :=H ;
Left :=L ;
Top :=T ;
Width :=W;
Font.Name:='MS Sans Serif';
Name:=RGName;
Font.Size:=FontSize;
Items.Add('Edit1);
Items.Add('Edit2');
ItemIndex:=0;
OnClick:=Form1.RadioGroupClick;
end;
end;
procedure TForm1.RadioGroupClick(Sender: TObject);
var
E1,E2:TEdit;
begin {1}
E1:=TEdit(FindComponent('Edit1'));
E2:=TEdit(FindComponent('Edit2'));
E1:=TEdit.Create(MyPanel);
E2:=TEdit.Create(MyPanel);
if E1=nil then showmessage('E1=Nil');
if E2=nil then showmessage('E2=Nil');
If MyRadioGroup.Name='RD1' then {with TEDIT}
begin {If}
If Assigned(E1) and Assigned(E2) then
begin {2}
Case MyRadioGroup.ItemIndex of
0: begin
E1.Visible:=true;
E2.Visible:=False;
end;
1:begin
E1.Visible:=False;
E2.Visible:=true;
end;
end;{Case}
end;{2}
end;{If}
end;{1}
procedure TForm1.FormCreate(Sender: TObject);
begin
{Pannel Left,Top,Hieght,Width}
CreationPanel(80,100,300,180,'Panel1','Panel 1');
Creation_Edit(30,184,10,'Edit1','Panel1',true);
Creation_Edit(30,234,10,'Edit2','Panel1',false);
{RadioGroup Left,Top,Height,Width,FontSize,Tab}
Creation_RadioGroup(30,12,90,120,12,'RD1','Panel1');
end;
end.

Answer 1

OK your code is a complete mess, but I can tell you what your underlying problem is (i.e. the one that caused you to ask the question.)
Firstly Nasreddine is right about removing
E1:=TEdit.Create(MyPanel);
E2:=TEdit.Create(MyPanel);
That is a complete floundering (try anything) attempt because E1 and E2 return nil.
You should not be trying to stop them being nil. Instead you should ask yourself why they are nil.
And the answer to that is that Edit1 and Edit2 are not owned by Form1. They are owned by MyPanel.
MyEdit:=TEdit.Create(MyPanel);
So your code should read
procedure TForm1.RadioGroupClick(Sender: TObject);
var
E1,E2:TEdit;
begin {1}
E1:=TEdit( MyPanel.FindComponent('Edit1'));
E2:=TEdit(MyPanel.FindComponent('Edit2'));
if E1=nil then showmessage('E1=Nil');
if E2=nil then showmessage('E2=Nil');
//etc...
end;{1}