dark blue wallpaper

from lue to dark blue.

jtara

Apr 14, 11:14 AM

Interesting possibility. It would be extremely difficult to emulate a complete iOS device (custom ASICs and all). But Apple could emulate just enough ARM instructions to emulate an app that was compiled by Xcode & LLVM (which would limit the way ARM instructions were generated), and used only legal public iOS APIs (instead of emulating hardware and all the registers), which could be translated in Cocoa APIs to display on a Mac OS X machine.

There's no need to emulate ARM instructions, though. And they already do emulate all of the complete iOS devices, at least sufficiently to run iOS apps on OSX.

Apple provides developers with a complete emulation package for testing their iOS apps on OSX. Apps are cross-compiled to x86 code. They also provide the complete set of iOS SDKs, cross-compiled to X86 code.

An emulator handles the device hardware - touchscreen, display, sound system, GPS (REALLY simple emulation - it's always sunny in Mountain View...), etc. If an iPhone or iPad are attached via USB cable, the emulator can even use the accelerometer and gyroscope in the device. Obviously, this could be easily changed to use some new peripheral device.

Other than device emulation, the apps suffer no loss of speed, since they are running native x86 code. In fact, they run considerably faster (ignoring, for this discussion, device emulation) than then do on an actual iOS device.

All Apple would need to give consumers the ability to run iOS apps on their Macs would be to provide them with the emulator (or, more likely, integrate it into the OSX desktop. I think end-users would find the picture of an iPhone or iPad that the emulator draws around the "screen" cute for a couple of days, but then quickly tire of it...), and add an additional target for developers.

What we've seen certainly seems to suggest that's what this is. HOWEVER:

1. For a single app to be compatible with both ARM and x86, they would need to introduce a "fat binary" similar to what they did with the transition from PowerPC to x86. This would bloat apps that are compatible with both to double their current download size. Current Universal (iPhone/iPad) apps are NOT fat binaries. They have multiple sets of resources (images, screen layouts, etc.) and the code needs to have multiple behaviors depending on the device. i.e. the code has to check "is this an iPad? If so do this...

Currently, developers have to create separate binaries for use on the emulator or the actual device.

2. Several developers have checked-in here to say that their apps are listed this way. None have offered that they had any advance knowledge of this, or did anything to make it happen. If this is about ARM/x86 fat binaries, the developer would have had to build their app that way. And even if it didn't require a re-build, I think it's highly unlikely that Apple would start selling apps on a new platform without letting the developers know!

3. Apple is *reasonably* fair about giving all developers access to new technology at the same time. They also generally make a public announcement at the same time as making beta SDKs available to developers. (Though the public announcement may be limited in scope and vague.) There are so many developers, that despite confidentiality agreements, most of the details get out to the public pretty quickly, though perhaps in muddled form. While Apple DOES hand-pick developers for early-early access, it's typically not THAT early. A few weeks, max.

I do think that an x86 target for iOS apps is inevitable. Just not imminent.

My best guess is that this was a screw-up by the web-site developers. Perhaps they did a mockup of the app store for the marketing people, selected some apps or app categories that seemed likely candidates, and slipped-up and it went live on the real app store.