Solution 1:

You currently cannot install Xcode on an iPad or iPhone, or any device other than a mac running OSX. There have been discussions & questions asked about it before; basically you shouldn't hold your breath.

If you have a mac you can always consider VNC if you want to do work remotely on your iPad, but to me it sounds like you don't have a mac and were hoping the iPad could serve as your development environment.

Solution 2:

Xcode is an IDE available exclusively for the Mac OS operating system. There is no mobile version of the software. The link you provided is to the Mac App Store, which is its own separate entity from the App Store for iOS devices.

Solution 3:

Xcode is a Mac App, not an iOS App. As such, it doesn't run on the iPad. The program you linked to, http://itunes.apple.com/us/app/xcode/id497799835?mt=12, is in the Mac app store, not the iOS App store.

There might be some confusion because Xcode can be used to develop iOS apps, but it itself is a Mac app only.

Solution 4:

As with the other answers, you can't directly because OS X and iOS are different platforms with different restrictions and apps (duh).  You can however accomplish what you're attempting to do with an OS X machine running and connected to the Internet in order to compile the builds for your iPad.

This is exactly how the Dringend app works (http://dringend.cc/).  It runs on your iPad as a slimmed-down 3rd-party Xcode replacement (it even understands .xcodeproj files!), and uses Xcode via remote OS X host to do the dirty-work.

I thought I read something somewhere about another start-up working towards a product with the same premise, but provides the OS X build-machines as a paid service— I'll update this if I find their name.  Until then, there's always OS X hosting.