Use Keychain To Store Device Identifier

Question

I noticed that my identifierForVendor always changes. Someone told me that it doesn't change when you download from iTunes. I'm not so sure about it, though. So, I want to store the first identifierForVendor generated. I found this class, JNKeychain from one of the posts i checked. It can store password and other data. I tried using that to store my identifierForVendor. Even after deleting my app and reinstalling using XCode, I was able to get the value I stored. Sounds good because this way, my identifierForVendor can persist regardless of whether it was downloaded from iTunes or not. However, I"m not very familiar with Keychain. I didn't even know we can store secure data using it. I read their documentation and it says there it's usually used to share data between applications and your apps should have same provisioning profile etc... I don't plan on sharing. I just want it to save my identifier so this is not a concern for me. My only concern is how long will my data last in the keychain storage? Will it be deleted after some time? or when I turn off my device? When i update ios version? Can it persist forever? Will keychain have a different behavior if I use developer/distribution profile?

Answer 1

The keychain entry will last as long as the device is not wiped or hard-reset or until the app deletes it. Apps can be deleted and replaced, but the keychain entry will remain. If an app from developer profile is overlaid with enterprise profile or app store the keychain entry should be fine.