ShowModal在FireMonkey移动应用程序对话框

This is the only code that changes between the first and second code snippets:

 dlg.ShowModal(procedure(ModalResult: TModalResult)
    begin
      if ModalResult = mrOK then
      // if OK was pressed and an item is selected, pick it
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
      dlg.DisposeOf;
    end);

 dlg.ShowModal(procedure(ModalResult: TModalResult)
    begin
      if ModalResult = mrOK then
      // if OK was pressed and an item is selected, pick it
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
      dlg.DisposeOf;
    end);

第一个代码片段：典型的代码调用的ShowModal

procedure THeaderFooterForm.btnPickClick(Sender: TObject);
var
  dlg: TForm1;
begin
  dlg := TForm1.Create(nil);
  try
    // select current value, if avaialble in the list
    dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);
 
    if dlg.ShowModal = mrOK then
      // if OK was pressed and an item is selected, pick it
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
  finally
    dlg.Free;
  end;
 
end;

procedure THeaderFooterForm.btnPickClick(Sender: TObject);
var
  dlg: TForm1;
begin
  dlg := TForm1.Create(nil);
  try
    // select current value, if avaialble in the list
    dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);
 
    if dlg.ShowModal = mrOK then
      // if OK was pressed and an item is selected, pick it
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
  finally
    dlg.Free;
  end;
 
end;

伪代码典型的ShowModal代码片段解读

这里是一个描述每个此过程的一部分：

声明局部变量
dlg: TForm1;
创建表格的形式和初始化成员
dlg := TForm1.Create(nil);
        dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);
显示的形式模态
if dlg.ShowModal = mrOK then
检查用户的结果和处理数据
if dlg.ListBox1.ItemIndex >= 0 then
      edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
 释放表单 dlg.Free;

声明局部变量
dlg: TForm1;
创建表格的形式和初始化成员
dlg := TForm1.Create(nil);
        dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);
显示的形式模态
if dlg.ShowModal = mrOK then
检查用户的结果和处理数据
if dlg.ListBox1.ItemIndex >= 0 then
      edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
 释放表单 dlg.Free;

第二个代码片段：作为一个匿名的方式在所有平台上调用的ShowModal

随着移动平台，你应该改变这种代码，悦目，让所有支持的目标平台上工作的ShowModal。

procedure THeaderFooterForm.btnPickClick(Sender: TObject);
var
  dlg: TForm1;
begin
  dlg := TForm1.Create(nil);
  // select current value, if available in the list
  dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);
 
  dlg.ShowModal(procedure(ModalResult: TModalResult)
    begin
      if ModalResult = mrOK then
      // if OK was pressed and an item is selected, pick it
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
      dlg.DisposeOf;
    end);
 
end;

procedure THeaderFooterForm.btnPickClick(Sender: TObject);
var
  dlg: TForm1;
begin
  dlg := TForm1.Create(nil);
  // select current value, if available in the list
  dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);
 
  dlg.ShowModal(procedure(ModalResult: TModalResult)
    begin
      if ModalResult = mrOK then
      // if OK was pressed and an item is selected, pick it
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];
      dlg.DisposeOf;
    end);
 
end;

匿名方法的ShowModal代码片段的伪代码解读

这里是一个描述发生了什么（做同样的事情，第一个代码段）在第二个代码片段：

Declare local variables
    dlg: TForm1;

Create form and initialize member in the form
    dlg := TForm1.Create(nil);
        dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);

Show the form modal
      dlg.ShowModal(procedure(ModalResult: TModalResult)

Check the user's result and process the data
    if ModalResult = mrOK then
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];

Free the form
          dlg.DisposeOf;

Declare local variables
    dlg: TForm1;

Create form and initialize member in the form
    dlg := TForm1.Create(nil);
        dlg.ListBox1.ItemIndex := dlg.ListBox1.Items.IndexOf(edit1.Text);

Show the form modal
      dlg.ShowModal(procedure(ModalResult: TModalResult)

Check the user's result and process the data
    if ModalResult = mrOK then
      if dlg.ListBox1.ItemIndex >= 0 then
        edit1.Text := dlg.ListBox1.Items [dlg.ListBox1.ItemIndex];

Free the form
          dlg.DisposeOf;