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.

The alternative example code below demonstrates how to do this for various URL schemes (eg mailto:, http:, https:, sms:, tel:, etc).

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.

Alternative example code for URL schemes

Note that LSGetApplicationForURL was deprecated in macOS 10.10 (Yosemite) in favour of LSCopyDefaultApplicationURLForURL which itself was deprecated in macOS 12 (Monterey), both functions are still working in macOS 12.0.1.

unit Unit1;

{$mode objfpc}{$H+}
{$modeswitch objectivec1}

interface

uses
  SysUtils, Forms, StdCtrls,
  MacOSAll, CocoaAll, CocoaUtils;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private

  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  myURL: NSURL;
  URLRef: CFURLRef;
  OSStatus: Integer;
  myStr: String;
begin
  // Create URL scheme from one of:
  // file:///
  // file://localhost/
  // mailto:
  // http:
  // https:
  // ftp:
  // sms:
  // tel:
  // facetime:
  // ... There are probably more.
  myURL := NSURL.alloc.initWithString(NSStr('mailto:'));

  // Check for default pplication
  OSStatus := LSGetApplicationForURL(CFURLRef(myURL), kLSRolesAll, Nil, @URLRef);

  // Check for error (eg application not found for URL = -10814)
  if(OSStatus <> 0) then
    begin
      Memo1.Append('LSGetApplicationForURL error status: ' + IntToStr(OSStatus));
      Exit;
    end;

  // Get CFString from CFURLRef, Cast to NSString, Convert to AnsiString
  myStr := NSStringToString(NSString(CFURLGetString(URLRef)));

  // Output to memo
  memo1.Append('LSGetApplicationForURL status: ' + IntToStr(OSStatus)
    + LineEnding + LineEnding + 'Default app: ' + myStr);

  // Housekeeping
  myURL.release;
end;

end.

See also

• Find the default web browser - cross-platform example.

External links

• Apple: NSWorkspace
• Apple: NSURL
• Apple: CFURL, CFURLRef
• Apple: LSGetApplicationForURL