Filename extension | .app, .framework, .kext, .plugin, .docset, .xpc, .qlgenerator, .component, .saver, .mdimporter, etc. |
---|---|
Uniform Type Identifier (UTI) | com.apple.bundle |
Container for | executable binary, metadata, other bundles, any other file needed to run the application. |
In NeXTSTEP, OPENSTEP, and their lineal descendants macOS, iOS, iPadOS, tvOS, and watchOS, and in GNUstep, a bundle is a file directory with a defined structure and file extension, allowing related files to be grouped together as a conceptually single item.
Examples of bundles that contain executable code include applications, frameworks, and plugins. This kind of bundle usually contains one file representing executable code, and files that represent resources such as nibs, templates, images, sounds, and other media. On some other systems, such as Microsoft Windows, these resources are usually included directly in the executable file itself at compile time. On older Macintoshes, a similar technique is used, where additional metadata can be added to a file's resource fork. Similar in concept are the application directories used in RISC OS and on the ROX Desktop.
Examples of bundles that do not contain executable code include document packages (iWork documents) and media libraries (iPhoto Library).
Bundles are programmatically accessed with the NSBundle
class in Cocoa, NeXTSTEP and GNUstep's Foundation frameworks, and with CFBundle
in Core Foundation. Bundles often include an Info.plist file for metadata. [1] The Uniform Type Identifier (UTI) for an Apple bundle is com.apple.bundle
. [2]
Filename extension | .app |
---|---|
Uniform Type Identifier (UTI) | com.apple.application-bundle |
Type of format | application software |
Container for | executable binary |
Extended from | Bundle |
Application bundles are directory hierarchies, with the top-level directory having a name that ends with a .app
extension.
In a macOS application bundle, the first directory in the bundle underneath the top-level directory is usually named Contents
. Within Contents
there is usually another directory, called MacOS
, which contains the application's executable code. The Contents
folder contains a file named Info.plist
, which contains application information, such as the software vendor's name, name of the files that contain the applications executable and icon, the version of the application, permissions requested, etc. Within the Contents
folder there is usually also a directory called Resources
, which contains the resources of the application. [3]
Among other things, the Resources
folder contains localized versions of the application's nib files.
Other common subdirectories include Plugins
, Frameworks
, _CodeSignature
and Shared Frameworks
. The Frameworks
directory contains frameworks used by the application, and are used even if another version of the framework exists on the system. The Shared Frameworks
directory contains frameworks that can be used both by the application that contains them, and other applications; they are used only if a newer version does not exist elsewhere on the system. Plugins
contains extensible code used by the application. The _CodeSignature
folder contains information used by the system to validate that the package to establish that the package originates from a trusted party, and has not been tampered with.
By default, the Finder displays application bundles, which can also be referred to as packages, as opaque files with no underlying structure; the contents of the bundle can be shown with the "Show Package Contents" context menu item.
GNUstep by default uses the name of the application to name the folder that contains application code. An alternative is to name them by the computer architecture and OS the code is intended for to form a fat binary, so the application can be opened on many platforms. [4] [5]
Filename extension | .framework |
---|---|
Uniform Type Identifier (UTI) | com.apple.framework |
Extended from | bundle |
macOS frameworks are also stored as bundles; [6] the top-level directory of a framework bundle has a name that is the name of the framework followed by the extension .framework
. In the top-level directory is a Versions
directory, with subdirectories for one or more versions of the framework, each subdirectory containing the dynamic library code for the framework, in a file whose name is the same as the name of the framework, possibly with a Headers
folder containing header files for the framework, and other subfolders such as Resources
. The Versions
directory also contains a symbolic link Current
to the directory for the current version of the framework. In the top-level directory are symbolic links to the contents of Versions/Current
. [7]
The Finder displays framework bundles as directories rather than as opaque files.
Although GNUstep uses frameworks, they are not usually stored as bundles. This is because the full semantics of framework loading are considered too alien to other platforms. [8]
Loadable bundles are bundles which contain code that can be loaded at runtime. [9] Loadable bundles usually have the extension .bundle
, and are most often used as plug-ins. On macOS, there is a way to load bundles even into applications that do not support them, allowing for third party hacks for popular applications, such as Safari [10] and Apple Mail. [11] [12] A feature inherited from NeXTSTEP, GNUstep has the -[NSBundle principalClass]
interface too.
By default, the Finder displays loadable bundles, which can also be referred to as packages, as opaque files with no underlying structure; the contents of the bundle can be shown with the "Show Package Contents" context menu item.
There are many macOS applications which utilize their own custom bundle format (e.g. CandyBar .iContainer
, Aperture .aplibrary
, VMware Fusion .vmwarevm
, etc.).
An .lproj file is a bundle that contains localization files for OpenStep, macOS, or GNUstep software. It typically contains the .nib
files for a given language along with .strings
files and images if needed (for example, ReadMe or license files). These localized files are used by installer makers to customize install packages. They are also included in an application bundle.
NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT Computer in the late 1980s and early 1990s and was initially used for its range of proprietary workstation computers such as the NeXTcube. It was later ported to several other computer architectures.
OpenStep is a defunct object-oriented application programming interface (API) specification for a legacy object-oriented operating system, with the basic goal of offering a NeXTSTEP-like environment on non-NeXTSTEP operating systems. OpenStep was principally developed by NeXT with Sun Microsystems, to allow advanced application development on Sun's operating systems, specifically Solaris. NeXT produced a version of OpenStep for its own Mach-based Unix, stylized as OPENSTEP, as well as a version for Windows NT. The software libraries that shipped with OPENSTEP are a superset of the original OpenStep specification, including many features from the original NeXTSTEP.
Cocoa is Apple's native object-oriented application programming interface (API) for its desktop operating system macOS.
GNUstep is a free software implementation of the Cocoa Objective-C frameworks, widget toolkit, and application development tools for Unix-like operating systems and Microsoft Windows. It is part of the GNU Project.
The resource fork is a fork or section of a file on Apple's classic Mac OS operating system, which was also carried over to the modern macOS for compatibility, used to store structured data along with the unstructured data stored within the data fork.
WebObjects was a Java web application server and a server-based web application framework originally developed by NeXT Software, Inc.
In computing, a loadable kernel module (LKM) is an object file that contains code to extend the running kernel, or so-called base kernel, of an operating system. LKMs are typically used to add support for new hardware and/or filesystems, or for adding system calls. When the functionality provided by an LKM is no longer required, it can be unloaded in order to free memory and other resources.
A fat binary is a computer executable program or library which has been expanded with code native to multiple instruction sets which can consequently be run on multiple processor types. This results in a file larger than a normal one-architecture binary file, thus the name.
VisualWorks is a cross-platform implementation of the Smalltalk language. It is implemented as a development system based on images, which are dynamic collections of software objects, each contained in a system image.
On the classic Mac OS, extensions were small pieces of code that extended the system's functionality. They were run initially at start-up time, and operated by a variety of mechanisms, including trap patching and other code modifying techniques. Initially an Apple developer hack, extensions became the standard way to provide a modular operating system. Large amounts of important system services such as the TCP/IP network stacks and USB and FireWire support were optional components implemented as extensions. The phrase "system extension" later came to encompass faceless background applications as well.
Project Builder was an integrated development environment (IDE) originally developed by NeXT for version 3 of the NeXTSTEP operating system by separating out the code editing parts of Interface Builder into its own application.
Interface Builder is a software development application for Apple's macOS operating system. It is part of Xcode, the Apple Developer developer's toolset. Interface Builder allows Cocoa and Carbon developers to create interfaces for applications using a graphical user interface. The resulting interface is stored as a .nib file, short for NeXT Interface Builder, or more recently, as an XML-based .xib file.
In the macOS, iOS, NeXTSTEP, and GNUstep programming frameworks, property list files are files that store serialized objects. Property list files use the filename extension .plist
, and thus are often referred to as p-list files.
Rich Text Format Directory, also known as RTFD, or Rich Text Format with Attachments, is a primary document format of TextEdit, an application native to NeXTSTEP and macOS which has also been ported to other versions of Unix. The file format is based on the Rich Text Format, but can also include "attachments" such as images and animations.
An application directory is a grouping of software code, help files and resources that together comprise a complete software package but are presented to the user as a single object.
Dynamic loading is a mechanism by which a computer program can, at run time, load a library into memory, retrieve the addresses of functions and variables contained in the library, execute those functions or access those variables, and unload the library from memory. It is one of the 3 mechanisms by which a computer program can use some other software; the other two are static linking and dynamic linking. Unlike static linking and dynamic linking, dynamic loading allows a computer program to start up in the absence of these libraries, to discover available libraries, and to potentially gain additional functionality.
webarchive is a Web archive file format available on macOS and Windows for saving and reviewing complete web pages using the Safari web browser. The webarchive format differs from a standalone HTML file because it also saves linked files such as images, CSS, and JavaScript. The webarchive format is a concatenation of source files with filenames saved in the binary plist format using NSKeyedArchiver. Support for webarchive documents was added in Safari 4 Beta on Windows and is included in subsequent versions. Safari in iOS 13 has support for web archive files. Previously there was a third party iOS app called Web Archive Viewer that provided this functionality.
In the Apple macOS operating system, a package is a file system directory that is normally displayed to the user by the Finder as if it were a single file. Such a directory may be the top-level of a directory tree of objects stored as files, or it may be other archives of files or objects for various purposes, such as installer packages, or backup archives.
Mac OS is the series of operating systems developed for the Macintosh family of personal computers by Apple Computer from 1984 to 2001, starting with System 1 and ending with Mac OS 9. The Macintosh operating system is credited with having popularized the graphical user interface concept. It was included with every Macintosh that was sold during the era in which it was developed, and many updates to the system software were done in conjunction with the introduction of new Macintosh systems.