What is IPA file ?

An .ipa file is an iPhone application archive file which stores an iPhone app. It is usually encrypted with Apple’s FairPlay DRM technology. Each .ipa file is compressed with a binary for the ARM architecture and can only be installed on an iPhone, iPod Touch, or iPad. Files with the .ipa extension can be uncompressed by changing the extension to .zip and unzipping.
.ipa files cannot be installed on the iPhone Simulator because they do not contain a binary for the x86 architecture. To run applications on the simulator, original project files which can be opened using the Xcode SDK are required.

How to create ipa File ?

•  In Xcode 3.2.5 use “Build And Archive” to create an IPA file.
• In Xcode 4  and 4.2 you can use “Product -> Archive” to archive an application in an .xcarchive bundle.

Creating an IPA is done along the same way as creating an .xcarchive

1. Product -> Archive.
2. After the Archive operation completes
3.  go to the Organizer
4. select your archive
5. select Share and in the “Select the content and options for sharing:” pane set Contents to “iOS App Store Package (.ipa) and Identity to iPhone Distribution (which should match your ad hoc/app store provisioning profile for the project).
6. Choose the location to save the ipa file.

• After clicking on share  “iOS App Store Package (.ipa)” option may be disabled.
  Cause:
  This happens when your build produces more than a single target: say, an app and a library. All of them end up in the build products folder and Xcode gets naïvely confused about how to package them both into an .ipa file, so it merely disables the option.

  Solution:

• go through build settings for each of the targets, except the application target, and set Skip Install flag to YES.
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