Prior to version 4.3 of Xcode, Apple bundled a load of command line tools with it that are used to compile native binaries, including PHP extensions. However, as of version 4.3, these tools are not bundled by default. Therefore, if you require these tools you need to take one of two actions:
1. If you already have Xcode 4.3 installed, go into the Components tab of the Download preferences panel and make sure Command Line Tools are selected
OR
2. Download and install the command line tools as an independent package from either;
a. Apple (requires Apple ID)
b. GitHub
Once you have the command line tools installed, you are able to compile native binaries.
If you found this post useful, it would be great if you could Like my Facebook page using the button in the sidebar. Thanks!