An NES emulator written in Swift for iOS, ported from fogleman's NES emulator in Go: https://github.com/fogleman/nes
This app uses the UIDocumentBrowserViewController for easy NES ROM (.nes) file browsing using the native Files app interface. During emulation, each PPU output frame is rendered to a UIView as a CGImage. The app uses AVAudioEngine for sound, with buffers scheduled periodically from the APU output. Everything is done using native iOS frameworks, and no third-party libraries.
- 6502 CPU emulation
- PPU emulation (picture processing unit)
- APU emulation (audio processing unit)
- Mapper emulation for several common mappers
- Touchscreen controls
- Gamepad controls using built-in GameController framework and extendedGamepad profile. MFi controllers, Sony DualShock 4, or Xbox One controllers should all work. Touchsreen controls auto-hide when a controller is paired for player 1, and auto-show when the player 1 controller disconnects. Whenever a second controller is paired, it should be mapped automatically for player 2.
- Builds successfully for iOS 13+, iPadOS 13+, or Mac Catalyst (macOS 10.15 Catalina), but the Catalyst build still needs some Mac-specific tweaks.
The following mappers have been implemented:
- NROM (0)
- MMC1 (1)
- UNROM (2)
- CNROM (3)
- MMC3 (4)
- AxROM (7)
- MMC2 (9)
This accounts for a good portion of the NES library, but there are still some big gaps remaining for popular mapper support.
For best performance, build the app for release mode instead of debug. Or, if you want better performance for debug builds, change these debug build settings under Swift Compiler - Code Generation:
- Disable Safety Checks = YES
- Exclusive Access to Memory = Compile Time Enforcement Only
- Optimization level = Optimize for Speed [-O]
- Add support for more mappers.
- Add setting to adjust audio sample rate, giving the user some control over the tradeoff between CPU usage and sound quality.
- Performance improvements (look for low hanging fruit in areas of the app that are taking the longest).
- On-screen control improvements (bigger tap areas, better layout).
- Save states