Не искам да наливам масло в огъня, но мисля че приложението може да се подкара на iOS 3 без почти никакъв проблем.
Просто в ProjectSettings -> Deployment -> iOS Deployment Target трябва да се зададе по-ниска версия:
Цитат
Code will load on this and later versions of iOS. Framework APIs that are unavailable in earlier versions will be weak-linked; your code should check for null function pointers or specific system versions before calling newer APIs. [IPHONEOS_DEPLOYMENT_TARGET]
iOS 3.0 - Code will not load on systems earlier than 3.0. [3.0]
iOS 3.1 - Code will not load on systems earlier than 3.1. [3.1]
iOS 3.1.2 - Code will not load on systems earlier than 3.1.2. [3.1.2]
iOS 3.1.3 - Code will not load on systems earlier than 3.1.3. [3.1.3]
iOS 3.2 - Code will not load on systems earlier than 3.2. [3.2]
iOS 3.2.1 - Code will not load on systems earlier than 3.2.1. [3.2.1]
iOS 3.2.2 - Code will not load on systems earlier than 3.2.2. [3.2.2]
iOS 4.0 - Code will not load on systems earlier than 4.0. [4.0]
iOS 4.0.1 - Code will not load on systems earlier than 4.0.1. [4.0.1]
iOS 4.0.2 - Code will not load on systems earlier than 4.0.2. [4.0.2]
iOS 4.1 - Code will not load on systems earlier than 4.1. [4.1]
iOS 4.2 - Code will not load on systems earlier than 4.2. [4.2]
iOS 4.3 - Code will not load on systems earlier than 4.3. [4.3]
Разбира се трябва да се тества на един телефон с iOS3 и на един с iOS4 за се види дали няма да доведе до някакви неразбории.
В България където jailbreak-a е масов спорт, уви минаването към нови версии е трудно и мъчително (да не кажа и невъзможно без custom FW).