Possibly like this:
OTA Distribution
To create the ipa you need B4i and a Mac or a hosted builder plus a whole host of other things all listed here in the forum.
Sending via email will not help you at all (much like the apk in android - which is possible) as Apple have a whole host of other requirements and on the receiver, they will not be able to install anyway.
So my counter questions would be : (which you can use as a guide to search here in the forum)
1. Do you have B4i ?
2. Do you have a Mac or the Hosted Builder ?
3. Do you have an Apple Developers Account ?
4. Have you created the required certificates ?
5. Have you got the above and already created the App ?
6. Do you want to distribute to just one user for testing ?
7. Have you heard of TestFlight ?
The above are just some pointers you might wish to search or possibly follow Erel's Tutorial videos.
As PS would say:
Enjoy...
