Can I force a user to upgrade my app?

Can I force a user to upgrade my app? Does 开发者_运维知识库Apple recommend it?

Yes, you can. Just check the version number when the application starts and if needed, bail out with an error screen. I don’t think Apple explicitly prohibits this. (And I doubt they would find out during the review.) Of course it’s annoying from the user’s viewpoint, I would only write something like that if there was no other option.

Yes you can force an upgrade to the user. You can call a webservice when your app start and check on your server if an update is available (you have to add an update when an update available on app store). If an update is available then you can present a view that will have the update button. When pressed this button will redirect the user to the installed app store app and open the upgraded app in it. (you should return this url in your webservice). Let me know in comments if you need more explanations.

And I don't know apple recommend this way. But I have seen this in one or two apps.

Extremely bad approach. My perfectly fine working app forces upgrade, which can not be supported due to obsolete iOS. I am not only forced, but moving away from the coupon app in determination to never use it web-based either. Security issue, if that is the reason for upgrade, should be patched for existing iOS.