Delphi多线程

MyThread = class(TThread)
  private
    procedure Execute;override;
  end;

procedure MyThread.Execute;
var
  i: integer;
begin
  for i:=0 to 20 do
  begin

//原因类似于oc，oc的标记变量需要手工定义，delphi不需要定义
    if not Terminated then
    begin
      Form1.Edit1.Text := IntToStr(i);
      Sleep(500);
    end
    else
      Break;
  end;

end;

if Assigned(tt) then
  begin
//    会首先把Terminated 这个变量=false
    tt.Free;
  end;