The APC extension should be a straightforward PECL install, but sadly it does not work on Mac OS X Lion. Attempting to install will result in make errors similar to the following:

In file included from /private/tmp/APC/apc.c:44:
/usr/include/php/ext/pcre/php_pcre.h:29:18: error: pcre.h: No such file or directory
In file included from /private/tmp/APC/apc.c:44:
/usr/include/php/ext/pcre/php_pcre.h:37: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
/usr/include/php/ext/pcre/php_pcre.h:38: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
/usr/include/php/ext/pcre/php_pcre.h:44: error: expected specifier-qualifier-list before ‘pcre’
/private/tmp/APC/apc.c:393: error: expected specifier-qualifier-list before ‘pcre’
/private/tmp/APC/apc.c: In function ‘apc_regex_compile_array’:
/private/tmp/APC/apc.c:454: error: ‘apc_regex’ has no member named ‘preg’
/private/tmp/APC/apc.c:454: error: ‘apc_regex’ has no member named ‘preg’
/private/tmp/APC/apc.c:455: error: ‘apc_regex’ has no member named ‘nreg’
/private/tmp/APC/apc.c:455: error: ‘apc_regex’ has no member named ‘nreg’
/private/tmp/APC/apc.c: In function ‘apc_regex_match_array’:
/private/tmp/APC/apc.c:487: error: ‘apc_regex’ has no member named ‘preg’
/private/tmp/APC/apc.c:487: error: ‘apc_regex’ has no member named ‘preg’
/private/tmp/APC/apc.c:488: error: ‘apc_regex’ has no member named ‘nreg’
/private/tmp/APC/apc.c:488: error: ‘apc_regex’ has no member named ‘nreg’
make: *** [apc.lo] Error 1
ERROR: `make' failed

Thankfully, the solution is simple. To being with, make sure you have Xcode installed. If you have xCode 4.3 or above, make sure you have the command line tools installed.

APC requires PCRE libraries and header files to be available, so we can download and install these from source:

• Download the latest PCRE from http://sourceforge.net/projects/pcre/files/latest/download?source=files
• Unzip the file
• cd into the unzipped pcre- directory and then type:

./configure
make
sudo make install

Next, we can install the APC extension using the normal PECL route:

sudo pecl install apc

Confirm that you have the following line in your php.ini file:

extension=apc.so

Restart Apache, if required:

sudo apachectl graceful

You should now have APC available, and you can confirm this by looking at your phpinfo output:

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