RAD Studio XE5 has problems running apps on the recently released iOS 7.1 simulator, while targeting an updated iOS 7.1 device seems to work fine (I haven't done it myself). The RAD Studio team had tested beta versions of 7.1 and everything was working smoothly, but in the final release of Xcode 5.1 Apple broke our integration, based on PAServer. A fix has been developed and is currently being tested internally.
We expect to make this fix available soon (meaning within a few days, likely next week), depending on the current testing. It will be a PAServer update, a hotfix freely available to XE5 Update 2 users.