Introduction

Note: This document was previously titled Cross-Development Programming Guide.

Xcode Developer Tools includes software development kits (SDKs) that enable you to develop software that can be deployed on specified versions of Mac OS X or iPhone OS, including versions different from the one you are developing on. This technology enables your application to be compatible with previous versions of the operating system, taking advantage of new features when they are available while gracefully degrading when running on older systems. Some Apple frameworks automatically modify their behavior based on the SDK an application was built against for improved compatibility.

Note: This document does not explain how to develop code that runs on both the Mac OS X and iPhone OS platforms. Although Xcode enables you to switch platforms by simply choosing a different SDK, there are fundamental design differences between Mac OS X and iPhone OS programs. See “Migrating from Cocoa" for more information.

You should read this document if your application needs to target a specific version or multiple versions of Mac OS X or iPhone OS.

Organization of This Document

This document contains the following chapters:

“Overview of SDK-Based Development” describes how SDK-based development works.
“Configuring a Project for SDK-Based Development” describes how to set up your project to use an SDK.
“Using SDK-Based Development” explains how to check for framework versions, deal with undefined methods and functions, and find deprecated APIs.

Last updated: 2009-09-09

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