macOS Find Default Application

This article applies to macOS only.

See also: Multiplatform Programming Guide

Overview

From time to time your application may need to determine the user's default application for opening certain content - for example, a web URL or a file system file. Example code which demonstrates how to do this is set out below. Note that these are obviously not the only two content for which you may wish to determine the user's default application, but the same general approach will apply for those other content types.

Example code

unit Unit1;

{$mode objfpc}{$H+}
{$modeswitch objectivec2}

interface

uses
  Classes,
  Forms,
  Dialogs,    // needed for ShowMessage()
  StdCtrls,   // needed for buttons
  CocoaAll,   // needed for Cocoa framework (origin the NeXTSTEP libraries)
  CocoaUtils; // needed for NSStringToString()

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private

  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  contentUrl: NSUrl;
  defAppUrl: NSUrl;
  defAppName: String;
begin
  contentUrl := NSUrl.URLWithString(NSSTR('https://sentinel.sentry.org/'));
  defAppUrl := NSWorkspace.sharedWorkspace.URLForApplicationToOpenURL(contentUrl);

  // Bundle ID (required)
  ShowMessage(NSStringToString(NSBundle.bundleWithURL(defAppUrl).bundleIdentifier));

  // Bundle Display Name (optional)
  defAppName := NSStringToString(NSBundle.bundleWithURL(defAppUrl).objectForInfoDictionaryKey(NSStr('CFBundleDisplayName').description));
  // Bundle Name (conventionally required)
  if (defAppName = '') then
    defAppName := NSStringToString(NSBundle.bundleWithURL(defAppUrl).objectForInfoDictionaryKey(NSStr('CFBundleName').description));
  // Cannot fail :-)
  if (defAppName = '') then
    defAppName := NSStringToString(defAppUrl.URLByDeletingPathExtension.lastPathComponent);

  // Show result
  ShowMessage(defAppName);
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  contentUrl: NSUrl;
  defAppUrl: NSUrl;
  defAppName: String;
begin
  contentUrl := NSUrl.URLWithString(NSSTR('file:///Users/trev/my_defaults.txt'));
  defAppUrl := NSWorkspace.sharedWorkspace.URLForApplicationToOpenURL(contentUrl);

  // Bundle ID (required)
  ShowMessage(NSStringToString(NSBundle.bundleWithURL(defAppUrl).bundleIdentifier));

  // Bundle Display Name (optional)
  defAppName := NSStringToString(NSBundle.bundleWithURL(defAppUrl).objectForInfoDictionaryKey(NSStr('CFBundleDisplayName').description));
  // Bundle Name (conventionally required)
  if (defAppName = '') then
    defAppName := NSStringToString(NSBundle.bundleWithURL(defAppUrl).objectForInfoDictionaryKey(NSStr('CFBundleName').description));
  // Cannot fail :-)
  if (defAppName = '') then
    defAppName := NSStringToString(defAppUrl.URLByDeletingPathExtension.lastPathComponent);

  // Show result
  ShowMessage(defAppName);
end;

end.