Demonstrating iOS in-development application I'm developing iOS application for my customer. At final point he asked me to share "preview" of an app via link before he could pay me for it. How do I do that?


How do I show my iOS app to someone, is there any other way aside from uploading it to AppStore and therefore making it public and needing developer account (I don't have at the moment)?
If I upload an app to AppStore, is it possible for my customer to "steal" and save it (through installing to jailbroken device for example and copying app with file manager), I suppose this is how users of jailbroken devices download and install paid apps for free using torrents?
What is the common practice of doing this, I mean demonstrating app in development to customer? On my own device? Bringing laptop with Xcode installed and using customer's device?
The most common way of doing this is through TestFlight, and you will need an Apple Developer Account.  

Setup your customer as either an external or internal user.  Upload the app to TestFlight.  The customer will be able to download the app and test it but it will not be available for the general public.

Of course, there's a bit more to it than what I just listed but it's not very difficult and you can upload the app multiple times (after each bug fix or app change) and the customer will be automatically notified to download the new version.  When you're ready to push it out to the public, you can do that.

Go here for more info on how to use it.