Question

I have been trying to start my application with hiden main form, but no luck. It
compiles and everything, but when I run it I get runtime error. When I use timer and set it to 1 millisecond and then call Application.MainForm.Hide it hides but it flashes i dont want that to happen

program Project1;
uses
  FMX.Forms,
  Unit1 in 'Unit1.pas' {Form1};

{$R *.res}

begin
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.MainForm.Visible := false;
  Form1.Visible:=false;
  Application.Run;
end.

Answer 1

In a FireMonkey application the Auto-created forms (are created) and the MainForm property is assigned in the Application.Run method. So the access violation is caused because the MainForm property and form1 variable is nil.

In order to access such properties you must execute the RealCreateForms method first

begin
  Application.Initialize;
  Application.CreateForm(TForm2, Form1);
  Application.RealCreateForms;
  //Application.MainForm.Left:=-Application.MainForm.Width;
  Application.MainForm.Visible:=False;
  Application.Run;
end.