In order to inspect iOS receipts, you have to access the application's sandbox by:

Once the sandbox is copied, the receipt can be inspected with a QuickLook plugin.

Installing the QuickLook Plugin

The QuickLook plugin is available for download from GitHub.

Then, open a Terminal window and type qlmanage -r in order to rebuild the QuickLook plugin database.

Connect the iOS device to your Mac and open the Xcode organizer.

Select the application; the application sandbox is visible on the lower right pane.

Click on the Download button in order to export the application's sandbox. The sandbox is exported as a xcappdata bundle.

Right-click on the xcappdata bundle and select the Show Package Contents item. This will open the bundle and reveal the application's sandbox.

Locate the AppData/StoreKit folder and select the receipt file.

Press the space key to trigger the QuickLook preview. A window with the content of the receipt is displayed.