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Comment by throwawaycert | Hacker News Reader

Any ability to execute arbitrary code is the ability to bypass the MAS. What's more, it's nice and efficient - iOS apps in development are compiled right to x86 machine code for the "simulator" that is little more than a thin VM.

100% of the projections I've seen about MacOS becoming a walled garden have been from people that don't actually have any real familiarity with Apple's ecosystem as developers.

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There are all sorts of restrictions Apple could place on software compiled "unofficially" with Xcode. For example, they could automatically sign it with testing certs that automatically expire after 7 days.

macOS is a more open platform because Apple has decided to leave it that way, not because the property is literally essential for development.

They already require periodic resigning of self-signed side-loaded apps on iOS, it doesn't stop even relatively casual users.

(That's actually the funniest part about all this, now that I think about it. While everyone is wailing and gnashing their teeth about some speculative possibility that macOS ends up locked down like iOS, Apple has been making iOS more open.)

So how would Apple enforce code signing on code that ran on top of a VM like Java or C# or scripting languages?

By not allowing JITs, just like on iOS.

So you really think Apple is not going to not allow the Mac to run any scripting language or program that runs on top of a VM? Do you think they are also going to take away shell access?

They are also not going to allow any Electron apps?

> So you really think Apple is not going to not allow the Mac to run any scripting language or program that runs on top of a VM?

No, I don't, double check which commenter you're replying to. :)

I'm just arguing Apple could lock down macOS if they wanted to, without making iOS development impossible.

iOS allows JITs.

This is exactly what I'm talking about. You're using bad or outdated second or third-hand info with no regard for the game of telephone involved in getting it to you, nor the anti-Apple zealots obfuscating the truth on its way.

Are you sure? I admittedly can't find a definitive source on this now, so perhaps the restriction is more nuanced than I realized.

What I do know is: if you try to use more intensive emulators like PPSSPP on a non-Jailbroken iOS device (via a developer account, enterprise cert, or similar), you will not get acceptable performance, because the emulator is forced to fall back into an interpreter mode.

Even on Jailbroken devices, the hacks required to make JIT work cause weird issues: https://github.com/hrydgard/ppsspp/issues/9186

The only JIT “restriction” is App Store policy. No downloaded code is allowed unless it’s JavaScript (and runs, as it happens, on one of the JITs iOS has built in). This is policy, not technical limits. You can even install a Python environment and code in it. And, as it happens, write code that downloads other code to be evaluated. Because you did it on your device with full knowledge. Not the developer who put it in the App Store.

I’m not even going to try and address whatever weird issues a console emulator might have, those always have problems being ported to non-x86 platforms, especially when they include a JIT. As it happens, dynamic recompilation of machine code not designed for that purpose can be pretty damn hard. Take a look at the posts the Dolphin emulator team make about the fun they encounter.

> I’m not even going to try and address whatever weird issues a console emulator might have, those always have problems being ported to non-x86 platforms, especially when they include a JIT. As it happens, dynamic recompilation of machine code not designed for that purpose can be pretty damn hard. Take a look at the posts the Dolphin emulator team make about the fun they encounter.

This isn't that! The JIT works when you remove iOS's sandbox (by Jaibreaking). And this applies to every iOS console emulator.

Oh, that's right, it's because iOS normally doesn't allow dynamic code modification in memory. That's not an iOS specific thing at all, Apple is just one of the few companies willing to make that nod to security.

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