I havent tried doing this but I know you can add multiple devices when testing apps. But what if the other device is not mine and is being synced/paired to other pc/mac? Can I safely install the app without erasing the content in that device? To my knowledge, an iphone can only be used to one pc/mac at a time. Since installing app requires itunes, then how can I install apps onto other people's device?
I asked this because I only have one and old iphone and my friend has the new iphone 4, which I can borrow to test the app, but I just want to be sure that nothing gets deleted.
You provide them with a ".mobileprovision" file that you create on Apple's DEV site, and then provide the other people that and the ".app" folder (located in the build/iphone/build/Release-iphoneos folder of your project)
they drag the mobileprovision file into iTunes, then the .app folder and the app shows up for syncing like any other app does/would
I posted this as a comment, and I guess it should be an answer.
You don't need to use your own iTunes account to install to other devices. They can use their own iTunes account or install over the air (OTA). Well, OTA installs do require the device to be at OS4 or later.