Who Should Read This Document?
Organization of This Document
One of the challenges facing Mac OS X application developers is the proliferation of methods to identify types of data. For example, some text files may be assigned a 'TEXT'
file type (as originally designed for Mac OS 9 and earlier), while others may simply have a .txt
filename extension. Some may have the .text
extension instead. In addition, some file types might be subsets of other types; an application that opens all .txt
files should probably also be able to open those with a .html
extension. Determining all the possible files an application could read could become impossible. The user experience then suffers, with users not understanding why an application can open one text file but not another.
To solve this problem, Apple has defined a syntax for special data identifiers called uniform type identifiers. Each UTI provides a unique identifier for a particular file type, data type, directory or bundle type, and so on. In addition, other type identifier namespaces for a particular type can be grouped under one UTI, with utility functions available to translate from one format to another.
This document is for all Mac OS X application developers that need to create or otherwise manipulate data that may be exchanged with other applications or services. For example, applications often need to be aware of the type of data they handle when:
Displaying, or manipulating, files, bundles, or folders
Accessing streaming data
Copying and pasting between documents or applications
Dragging and dropping between applications
Converting data or file contents using the Translation Manager
Support for uniform type identifiers is available in Mac OS X v10.3 and later.
This document is organized into the following chapters:
“Uniform Type Identifier Concepts” describes the syntax and usage of UTIs.
“Adopting Uniform Type Identifiers” describes how to adopt UTIs in your applications.
“System-Declared Uniform Type Identifiers ” lists UTIs declared by the system.
© 2004, 2008 Apple Inc. All Rights Reserved. (Last updated: 2008-04-08)