DailyTip
Latest
Xcode 3.2 Daily Tip: Analyzing Your Code
More Xcode 3.2 tips for Mac and iPhone developers. The LLVM/Clang static analyzer bundled with the Snow Leopard developer tools automatically detects a variety of memory management bugs in Objective-C programs. It's a terrific tool for finding memory leaks and other issues and it is now easily available to all developers, both for the Macintosh and iPhone platforms. I first learned about using the analyzer with iPhone projects from a blog post by Joe Heck of rhonabwy.com. Heck pointed out that the Intel-only analyzer worked with the Intel-based Simulator code generated by the iPhone SDK, letting you use the analyzer with your iPhone projects. At that time, you had to download a copy of the analyzer, install it by hand, and run it from the command line. It was amazingly helpful but a bit of a pain to use. No more. Xcode 3.2 incorporates the static analyzer tool directly into its IDE. Choose Build > Build and Analyze (Command-Shift-A) and the analyzer automatically checks your code. and presents any bugs detected by the analyzer. Static analysis evaluates source code to automatically find bugs, issuing hints that are similar in nature to compiler warnings but targeted at Foundation (Cocoa) and Core Foundation memory management. Each bug is marked with a blue icon and a description. I do wish that the text didn't seem to "cut off" so abruptly. Resizing the Xcode editor window does not affect the hard right alignment of the bug reports. This bug refers to the local watcher variable, which is allocated and initialized but not released. The tool is not perfect. It may flag nonexistent "bugs" in programs, so there are definitely false positive results that will show up as well as gray areas. In this example, the watcher is used until the application teardown, so the fact that it's leaking is not really a problem. That having been said, the analysis is amazingly helpful and if you do find real bugs, the Clang Static Analyzer team solicits bug reports. To learn more about your bug, click the blue branch icon in the code itself. The analyzer offers a detailed view of the bug and its issues. This presentation provides more information about the specifics of the issue at hand. In this detail view, clicking any single blue arrow opens the Build Results pane, showing the analyzer result list. Hide or show analyzer information by clicking the blue branch icon in the left gutter. It's easy to overlook the new built-in static analysis feature of Xcode 3.2, but you'd be missing out on a great feature if you didn't explore it further.
Xcode 3.2 Daily Tip: Upgrading Xcode
For those about to code, we salute you. Developers: are you ready to upgrade your new Snow Leopard install to Xcode 3.2? The Xcode installer package appears in your Snow Leopard disc's Optional Installs folder. Double-click the mpkg file to open the installer and begin the installation process. Xcode 3.2 offers a number of really great new features, several of which will be highlighted in upcoming daily tips. Standouts include the new built-in static code analysis, the two new LLVM compiler front ends (GCC 4.2 and Clang), and the new Build Results window. Until you install, you may run into problems using the standard C compiler from the command line. (It threw errors about not finding <stdio.h>, etc.) This despite the fact that I had already re-installed the iPhone SDK. Once I upgraded to the new Xcode, and rebooted, the command line cc started working again. The reboot step seemed necessary because cc didn't work until I did so. There might have been a less extreme alternative I'm not aware of to use instead. (If you know of one, please let me know in the comments!) You'll need to re-install your iPhone SDK packages as well. Make sure you download the SDK versions that were built specifically for Snow Leopard. The iPhone Dev Center provides both Leopard and Snow Leopard SDKs for each of its standard and beta distributions. Install these packages after upgrading to Xcode 3.2. I did not and ran into trouble with project creation (as well as the already mentioned command line cc) until I finally got the install order corrected. Update: Remember, the iPhone SDK packages do not include Xcode 3.2, so just downloading the iPhone SDK for Snow Leopard will not upgrade Xcode. Thanks go to hatfinch for his help.
