iOS JIT Explained: How to Enable JIT with StikDebug for Switch Emulation (iOS 17, 18, 26 — October 2026)

JIT (just-in-time compilation) is how an emulator translates a Switch game's ARM machine code into code your phone can run directly, while the game is running. For security, iOS blocks normal apps from generating executable code and only allows it when a debugger is attached to a sideloaded app. That is why MeloNX, the Switch emulator for iPhone and iPad, needs a tool like StikDebug to turn JIT on. As of October 2026, StikDebug is stable on iOS 17.4 to 18.x. It also works on iOS 26 and later, but only with apps that developers have updated, and MeloNX has been updated.

Why Switch emulators need JIT

1. Switch games are ARM code. An emulator either interprets it one instruction at a time (an interpreter) or translates it to native code first (JIT).
2. Interpreters are compatible but very slow, far too slow for Switch-class games. MeloNX puts it plainly: it won't run without JIT.
3. JIT requires an app to write code into memory and then make that memory executable. iOS doesn't allow this by default, only when a debugger is attached, and that needs the get-task-allow entitlement that comes with developer signing.
4. App Store and TestFlight apps can't carry get-task-allow, so they can never get JIT. Apple has allowed emulators on the App Store since April 2024, but not JIT.
5. So the flow is: sideload MeloNX with an Apple ID (it gets get-task-allow), attach StikDebug, a debugger that lives on your phone, and JIT is on.

For sideloading and installation, see the iPhone and iPad guide.

Quick reference by iOS version

Why iOS 26 made it harder: TXM

iOS 26 introduced TXM (Trusted Execution Monitor). On devices with TXM, even with JIT permission, a memory page the app writes code into must first be written once by the debugger before it can execute; the debugger's write is the authorization. That's why JIT broke completely when iOS 26 first shipped.

The fix needs both sides:

• The app: the emulator's JIT memory allocator has to follow the iOS 26 JIT protocol StikDebug published, handing every executable region to the debugger for preparation at launch.
• StikDebug: runs the matching script. The recommended one is the general-purpose universal.js; the older legacy.js is kept only for compatibility. Apps can also bundle their own script and pass it to StikDebug via a URL scheme.

So picking universal.js won't make an app that hasn't been updated support JIT. Also, the authorization belongs to the debug session: after the app fully quits, you have to authorize again, and it only works at launch, never mid-game.

TXM vs non-TXM devices

What StikDebug is

• StikDebug (formerly StikJIT) is an on-device debugger and JIT enabler built on the idevice library. It supports iOS 17.4 and later and needs no computer after the first pairing.
• Features: JIT for sideloaded apps with get-task-allow, app launching, logs, scripts (mainly for iOS 26 JIT), app expiry dates, process management and location simulation.
• It is no longer on the App Store. The official install methods are an AltSource, a direct IPA or building it yourself, all on its official project page.
• As of 2026-10-30 the latest version is 3.2.0, released that day, which adds creating and managing pairing files on the device itself. The feature is brand new and its real-world results are not yet confirmed.

What you need:

Enabling JIT, step by step (overview)

1. Sideload MeloNX and StikDebug, and make sure MeloNX was sideloaded with an Apple ID (apps signed with enterprise certificates don't get get-task-allow).
2. Prepare a pairing file. The official guide uses iloader on a computer (Windows needs iTunes, Linux needs usbmuxd): choose Manage Pairing File, then click Place next to StikDebug. Impactor can place it too. Your phone needs a passcode and must be unlocked and trusting the computer. Since StikDebug 3.2.0 you can also create one on the device.
3. Open LocalDevVPN, tap Connect, and stay on Wi-Fi.
4. Open StikDebug, tap Enable JIT and pick MeloNX from the list.
5. On iOS 26 TXM devices: in StikDebug's Scripts, long-press universal.js and set it as default or assign it to MeloNX. From then on, always launch MeloNX from StikDebug.
6. Whenever MeloNX fully quits, launch it from StikDebug again.

After every phone restart, StikDebug has to mount the Developer Disk Image (DDI) again, so give it a moment the first time you open it. System updates or resets invalidate the pairing file, and occasionally it breaks for no clear reason; just make a new one.

SideStore's built-in JIT

SideStore 0.6.2 and later include a built-in JIT option (long-press an app in My Apps > enable JIT) for older iOS versions and devices without TXM. iOS 26 TXM devices still need StikDebug and a script. SideStore's docs list MeloNX among the apps that work on iOS 26.6 and 27 (as of 2026-06-17), noting that "iOS 26 broke JIT again" and only a few apps work on 26.6 and 27.

The EU and Japan

Only what reliable sources confirm:

• AltStore PAL is an Apple-approved alternative marketplace. Its site says it's available only in the EU, Japan and Brazil, and a VPN won't change that. Japan opened up to alternative marketplaces with iOS 26.2 (2025-12-18), and AltStore PAL launched there the next day.
• PAL apps still go through Apple notarization, and Apple's position is that JIT apps don't pass. Delta removed JIT from both its App Store and PAL versions, and in 2024 UTM was refused notarization even for PAL, later shipping only UTM SE without JIT.
• Since April 2025, EU users can install AltStore Classic through AltStore PAL and then use StikDebug to enable JIT for apps installed by Classic. 9to5Mac reported that this is how MeloNX runs at full speed in the EU.
• The iOS 26 and 27 TXM rules apply in the EU too: you still need StikDebug, an updated app and a script.
• Claims that EU users get JIT automatically had no reliable source as of October 2026. Don't count on it.

Common errors

For the messages MeloNX itself shows (Waiting for JIT, JIT Not Acquired, the memory entitlement, MeloNX Crashed! and more), see MeloNX errors.

StikDebug 3.1.12 (2026-09-27) fixed DDI problems on versions below iOS 26.4 and improved the TXM scripts, so update StikDebug first when something odd happens. More Apple coverage is on the iOS platform hub, and terms are explained in the glossary.