Despite recent policy changes that allow emulators on the Apple App Store, the DolphiniOS emulator for Nintendo Wii and GameCube will not be making its debut there. The developers confirmed this decision last Friday, citing restrictions on crucial technology that hinder their app’s performance.
DolphiniOS, a variant of the widely used Dolphin emulator, relies on a technique known as Just-in-Time (JIT) compilation to efficiently translate the PowerPC-based code of GameCube and Wii games into a form that other devices, including iPhones, can process. This method significantly enhances the smoothness of game emulations.
Even with the recent App Store policy changes, DolphiniOS still cannot be submitted to the App Store due to Apple's restrictions.
— DolphiniOS (@DolphinforiOS) April 14, 2024
Dolphin requires access to JIT support for fast CPU emulation, but Apple continues to heavily restrict access to this feature.
However, Apple’s current policy restricts third-party applications from utilising JIT compilers, a rule from which only a few apps like Safari and certain web browsers in Europe are exempt. OatmealDome, the developer behind DolphiniOS, shared that they had sought an exception under the Digital Markets Act (DMA) for JIT support, but Apple rejected their request a few weeks ago.
Alternatives and performance issues
To circumvent the JIT restriction, developers could potentially use an “interpreter” mode, which processes the game code in a significantly slower manner than JIT. OatmealDome demonstrated the extent of this slowdown with two videos comparing the performance of Mario Kart Wii on an iPhone 15 using both techniques. The videos clearly showed that the interpreter method delivers a much poorer gameplay experience.
The recent relaxation of Apple’s emulator policy has already seen apps like Delta rapidly rise to prominence in the App Store. However, without JIT compiler support, DolphiniOS faces too great a handicap in performance to join its peers.
While Apple’s stance on JIT usage is firm, the future of other game emulators on iOS could hinge on further policy adjustments or technical workarounds that don’t compromise game performance.