Python in Xcode 4+?

I figured it out! The steps make it look like it will take more effort than it actually does.

These instructions are for creating a project from scratch. If you have existing Python scripts that you wish to include in this project, you will obviously need to slightly deviate from these instructions.

If you find that these instructions no longer work or are unclear due to changes in Xcode updates, please let me know. I will make the necessary corrections.

Open Xcode. The instructions for either are the same.
In the menu bar, click “File” → “New” → “New Project…”.
Select “Other” in the left pane, then "External Build System" in the right page, and next click "Next".
Enter the product name, organization name, or organization identifier.
For the “Build Tool” field, type in /usr/local/bin/python3 for Python 3 or /usr/bin/python for Python 2 and then click “Next”. Note that this assumes you have the symbolic link (that is setup by default) that resolves to the Python executable. If you are unsure as to where your Python executables are, enter either of these commands into Terminal: which python3 and which python.
Click “Next”.
Choose where to save it and click “Create”.
In the menu bar, click “File” → “New” → “New File…”.
Select “Other” under “OS X”.
Select “Empty” and click “Next”.
Navigate to the project folder (it will not work, otherwise), enter the name of the Python file (including the “.py” extension), and click “Create”.
In the menu bar, click “Product” → “Scheme” → “Edit Scheme…”.
Click “Run” in the left pane.
In the “Info” tab, click the “Executable” field and then click “Other…”.
Navigate to the executable from Step 5. You might need to use ⇧⌘G to type in the directory if it is hidden.
Select the executable and click "Choose".
Uncheck “Debug executable”. If you skip this step, Xcode will try to debug the Python executable itself. I am unaware of a way to integrate an external debugging tool into Xcode.
Click the “+” icon under “Arguments Passed On Launch”. You might have to expand that section by clicking on the triangle pointing to the right.
Type in $(SRCROOT)/ (or $(SOURCE_ROOT)/) and then the name of the Python file you want to test. Remember, the Python program must be in the project folder. Otherwise, you will have to type out the full path (or relative path if it's in a subfolder of the project folder) here. If there are spaces anywhere in the full path, you must include quotation marks at the beginning and end of this.
Click “Close”.

Note that if you open the "Utilities" panel, with the "Show the File inspector" tab active, the file type is automatically set to "Default - Python script". Feel free to look through all the file type options it has, to gain an idea as to what all it is capable of doing. The method above can be applied to any interpreted language. As of right now, I have yet to figure out exactly how to get it to work with Java; then again, I haven't done too much research. Surely there is some documentation floating around on the web about all of this.

Running without administrative privileges:

If you do not have administrative privileges or are not in the Developer group, you can still use Xcode for Python programming (but you still won't be able to develop in languages that require compiling). Instead of using the play button, in the menu bar, click "Product" → "Perform Action" → "Run Without Building" or simply use the keyboard shortcut ^⌘R.

Other Notes:

To change the text encoding, line endings, and/or indentation settings, open the "Utilities" panel and click "Show the File inspector" tab active. There, you will find these settings.

For more information about Xcode's build settings, there is no better source than this. I'd be interested in hearing from somebody who got this to work with unsupported compiled languages. This process should work for any other interpreted language. Just be sure to change Step 5 and Step 16 accordingly.

python xcode xcode7

I've created Xcode 4 templates to simplify the steps provided by Tyler.
The result is Python Project Template for Xcode 4.

Now what you need to do is download the templates, move it to /Developer/Library/Xcode/Templates/Project Templates/Mac/Others/ and then new a Python project with Xcode 4.

It still needs manual Scheme setup (you can refer to steps 12–20 provided by Tyler.)