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Troubleshooting Your Built Application

Here are the most typical behavior problems you’ll observe when your application runs natively on an Intel-based Macintosh computer:

• The application crashes.

• There are unexpected numerical results.

• Color is displayed incorrectly.

• Text is not displayed properly—characters from the Last Resort font or unexpected Chinese or Japanese characters appear.

• Files are not read or written correctly.

• Network communication does not work properly.

The first two problems in the list are typically caused by architecture-dependent code. On an Intel-based Macintosh computer, an integer divide-by-zero exception results in a crash, but on PowerPC the same operation returns zero. In these cases, the code must be rewritten in an architecture-independent manner. “Architectural Differences” discusses the major differences between Macintosh computers that use PowerPC and Intel microprocessors. That chapter can help you determine which code is causing the crash or the unexpected numerical results.

The last four problems in the list are most often caused by byte-ordering differences between architectures. These problems are easily remedied by taking the byte order into account when you read and write data. The strategies available for handling byte ordering, as well as an in-depth discussion of byte-ordering differences, are provided in “Swapping Bytes.” Keep in mind that Mac OS X ensures that byte-ordering is correct for anything it is responsible for. Apple-defined resources (such as menus) won’t result in problem behavior. Custom resources provided by your application, however, can result in problem behavior. For example, if images in your application seem to have a cyan tint, it’s quite likely that your application is writing alpha channel data to the blue channel. For this specific issue, depending on the APIs that you are using, you’d want to consult the sections “GWorlds,” “Pixel Data ,” or other graphics-related sections in “Guidelines for Specific Scenarios.”

Apple engineers prepared a lot of code to run natively on an Intel-based Macintosh computer—including the operating system, most Apple applications, and Apple tools. The guidelines in this book are the result of their work. In addition to the more common issues discussed in “Architectural Differences” and “Swapping Bytes,” the engineers identified a number of narrowly focused issues. These are described in “Guidelines for Specific Scenarios.” You will want to at least glance at this chapter to see if your code can benefit from any of the information.

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