Remove controls from a scrollbox - delphi

Question

I am dynamicaly (at run time) adding controls into a TScrollBox using myScrollBox.AddObject
Now I need to remove all the controls I added to put new ones.
I tryed myScrollBox.Controls.Clear but after I call that function, any control I add are not showing up.
(Warning: I'm new to delphi and Firemonkey)
Update 1
Here is how I add my objects (this is just a test function)
procedure TMainForm.TaskDetailsAdd;
var
btn1 : TButton;
intI : Integer;
count: Integer;
begin
scbTaskVariables.BeginUpdate;
count := 0;
for intI := 0 to 100 do
begin
btn1 := TButton.Create(self);
btn1.Text := 'Salut ' + IntToStr(intI);
btn1.Parent := scbTaskVariables;
btn1.OnClick := Button1Click;
btn1.Tag := intI * 10;
btn1.Position.Y := intI * 50;
btn1.Position.X := intI * 15;
scbTaskVariables.AddObject(btn1);
count := scbTaskVariables.ControlsCount;
end;
scbTaskVariables.EndUpdate;
end;
The funny thing is that if I place a break point on count := scbTaskVariables.ControlsCount
I can see that ControlsCount goes from 0 to 1 for the first control and then it stays to 1 for the others.
Update 2
I submitted QC#125440.

Answer 1

The inverse of AddObject is RemoveObject. Call ScrollBox.RemoveObject(aChildObject) for each child object that you wish to remove.
The alternative is to set the Parent property of the child object. Set it to ScrollBox to add it. Set it to nil to remove it. This is interchangeable with AddObject and RemoveObject. You can do it either way.
However, when you attempt to do this, just as your said, attempts to add new controls fail if you have removed controls earlier. This would appear to be a bug. Please submit a QC report.
I tested on XE6.

Answer 2

Try with:
myScrollBox.Content.DeleteChildren;

Answer 3

I have added this as an Answer but as there are bugs in FMX it should be considered as a workaround at this stage.
I spent some time on your problem about deleting your buttons, but also to tried to find out more about the bug. David was very quick to spot this and shows his experience.
Two of my findings were that (1) the AddObect() does not appear to work with the buttons, for some reason, they are not being seen as "Objects" but as "Components". (2) Also I found that creating btn1 with the "scrollBox" as its owner helped to achieve an adequate result.
I used 1 x TScrollbox, 2 x TButton and 4 x TLabel. The buttons left with their default name and the TScrollBox with Your default name. So you can just copy and paste. btn1 is made a private variable along with it's procedures.
procedure TMainForm.TaskDetailsAdd;
var
intI : Integer;
begin
label1.Text := IntToStr(scbTaskVariables.ComponentCount);
// Initial count = 1, Probably the scroll box.
if scbTaskVariables.ComponentCount >1 then
TaskDetailsDel; // Don't create Buttons with same Name if already exists.
scbTaskVariables.BeginUpdate;
for intI := 0 to 99 do
begin
Sleep(20); //Keeps the "Pressed Button" active to prove it is working
btn1 := TButton.Create(scbTaskVariables);
btn1.Parent := scbTaskVariables;
btn1.Position.Y := intI * 50;
btn1.Position.X := intI * 15;
btn1.Tag := intI * 10;
btn1.TabOrder := 10 + intI;
btn1.Name := 'MyBtn' + IntToStr(intI);
btn1.Text := 'Salut ' + IntToStr(intI);
btn1.OnClick := Button1Click;
if btn1.IsChild(scbTaskVariables) = true then
Label2.Text := 'True'
else // All this, proves buttons not seen as children.
Label2.Text := 'False';
scbTaskVariables.AddObject(btn1);
// AddObject() taken out as button is not seen as "FmxObject"
end;
scbTaskVariables.EndUpdate;
Label3.Text := IntToStr(scbTaskVariables.ComponentCount);
// Count now all created (includes ScrollBox).
Label4.Text := IntToStr(scbTaskVariables.ControlsCount);
end;
The "TaskDetailsDel" procedure was was quite easy once I had determined that I was really dealing with "Components"
procedure TMainForm.TaskDetailsDel;
var
intI : Integer;
count: Integer;
begin
label1.Text := '';
label2.Text := '';
label3.Text := '';
label4.Text := '';
for intI := 0 to 99 do
begin
Sleep(20); //Keeps the "Pressed Button" active to prove it is working
btn1 := TButton(scbTaskVariables.FindComponent('MyBtn' + IntToStr(intI)));
btn1.Parent := Nil;
FreeAndNil(btn1);
end;
Count := scbTaskVariables.ComponentCount;
Label1.Text := IntToStr(Count);
end;
Using the FindComponent line did the trick.
Press F1 and type the links into the URL Box; I found these interesting, especially seeing how TButton is derived in the VCL and FMX.
ms-help://embarcadero.rs_xe3/libraries/Vcl.StdCtrls.TButton.html
ms-help://embarcadero.rs_xe3/libraries/FMX.Controls.TButton.html
ms-help://embarcadero.rs_xe3/libraries/FMX.Types.TStyledControl.html
ms-help://embarcadero.rs_xe3/rad/Objects,_Components,_and_Controls.html
ms-help://embarcadero.rs_xe3/libraries/FMX.Types.TFmxObject.AddObject.html

Answer 4

The TScrollBox has by default 1 component that is of type TScrollContent that is responsible of the display of the other components. So if we delete him then nothing will be shown ever.
I created this little function to RemoveAllComponents inside the TScrollBox (Expect the TScrollContent):
procedure RemoveAllComponentsScrollBox(ScrollBox : TScrollBox);
var i : integer; Obj : TFmxObject;
begin
for I := ScrollBox.ComponentCount-1 downto 0 do
begin
if ((ScrollBox.Components[i] is TFmxObject) and not (ScrollBox.Components[i] is TScrollContent)) then
begin
Obj:=TFmxObject(ScrollBox.Components[i]);
Obj.Parent:=nil;
FreeAndNil(Obj);
end;
end;
end;
This method can be improved by recursivity