Apple recently changed its policies to allow game emulators on the App Store. This decision opened the doors for applications like deltaone of the most popular emulation tools that reached the top of the rankings in the App Store.
However, there is another popular emulator called Dolphin for Wii and Gamecube has issues with Apple’s policies.
Dolphin explained this in a blog post Apple’s resistance to apps that use JIT (Just-In-Time) means it won’t be available on the App Store for now.
The GameCube and Wii have a PowerPC based CPU. All modern Apple devices use an ARM-based CPU. It is not possible to run PowerPC code directly on an ARM CPU and vice versa. So if we want to run a GameCube or Wii game on an iPhone, it is necessary to translate the game’s PowerPC code into ARM so that the CPU can understand it.
To do this, Dolphin uses a so-called just-in-time recompiler (JIT). Whenever the emulated console wants to run game code, Dolphin uses its JIT to translate the PowerPC code into ARM and then executes the results.
Unfortunately, Apple generally does not allow apps on iOS to use JIT compilers. The only exceptions are Safari and alternative web browsers in Europe.
We submitted a DMA interoperability request to Apple to support JIT, but Apple rejected the request a few weeks ago.It’s hard to say exactly why Apple is so reluctant to open JIT support. They may consider you a security risk. (Looking at the various limitations and restrictions placed on JavaScript JITs for alternative web browsers in Europe, it seems there is concern that it could be abused.)
The problem is that JIT is essential for the emulator to perform well. The comparison between these two videos shows how important JIT is for running Dolphin on iOS.
This situation raises questions about the future of game emulators on the Apple platform. Although opening up to emulators like Delta is a step in the right direction, opposition to JIT leaves out important emulators like Dolphin.