---

Navigation Services Tasks

The Navigation Services API is fairly straightforward to use. It contains a modest number of functions and it performs a well-defined set of tasks. This chapter lists some overall guidelines for using the API, shows you how to accomplish the most common tasks, and discusses approaches to take if you need to customize a navigation dialog. The chapter contains these sections:

• “Guidelines for Using Navigation Services.” Read this first to get an idea how to best use the Navigation Services API in Mac OS X.

• “Steps for Providing a Navigation Dialog.” This section is a must-read because it discusses the five tasks required to display and process a navigation dialog.

• “Writing a Navigation Event-Handling Callback.” This is another required-reading section. If your application doesn’t provide an event-handling callback, it won’t be able to obtain and process actions taken by the user in a navigation dialog.

• “Filtering the Types of Files That Users Can Open.” Navigation Services can filter on the basis of the OSType of a file. You can get more sophisticated filtering by providing your own filtering routine. This section tells you how.

• “Writing a Preview Callback.” Only those developers who want to customize a preview display need to read this.

• “Controlling Settings in a Navigation Dialog.” Read this for information on how to set values for items in a navigation dialog.

• “Adding Custom Items to a Navigation Dialog.” If you want to add custom controls to a dialog, read this.

---