Metal in iOS 8: Explained

You know it's serious because Apple's Craig Federighi flipped a goat on stage at WWDC when he announced it.

Metal. If the name sounds hardcore, it's because it's a hardcore improvement to the way games will be able to perform on iOS 8. Metal represents a much more no-nonsense approach to getting the most out of the Apple A7's gaming performance, assuring users of the iPhone 5S, iPad Air and iPad mini with Retina display that their devices will continue to be top-notch game systems come this fall.

Right now in iOS 7 software called OpenGL ES sits in between the game and the core hardware that runs it, translating function calls into graphics commands that are sent to the hardware. It's a lot of overhead. And iOS 8 is getting rid of a lot of it.

near bare to the metal

Apple has developed a faster way to do it. They call the new system Metal, and it's not a reference to heavy metal music. It's a nod to the programming expression "close to the metal." But in Apple's hands, it's even closer than that.

What Metal means

Apple senior vice president of Software Engineering Craig Federighi describes iOS 8 Metal as providing "near bare to the metal access to the power of A7."

Federighi is talking about Apple's own A7 processor found in the iPhone 5s, iPad Air, and iPad mini with Retina Display. The A7 include's Apple's second generation custom CPU, Cyclone. It's 64-bit and based on the ARMv8 instruction set architecture. That's paired with an OpenGL 3.0 ES capable PowerVR Series 6 (Rogue) GPU, reportedly the G6430, and 1GB of DDR 3 RAM.

Metal lets developers target the power of that GPU far more directly than ever before. And it's reasonable to assume the same will be true of Apple's next processor, the A8, ostensibly coming with the next major iPhone and iPads later this year.

What Metal does

Draw calls

Draw calls, used to render all the objects in a scene in a 3D game, are up to ten times faster on the same hardware when using Metal. That means much faster, more responsive games with incredibly detailed environments.

iOS 8 gets a bump in game load time performance thanks to support for precompiled shaders. Shaders affect how an environment is lit and colored; they're an incredibly important part of rendering a realistic and immersive gaming experience. Precompiling them enables them to load faster.

With game developers always pushing the complexity envelope, this helps improve the user experience; after all, you don't want to sit around waiting for the game to load on your device.

Zen Garden

All this was brought home during the WWDC keynote when Epic Games showed off a new work in progress called Zen Garden. It's a free app coming after iOS 8 is released that lets you play with water, sand, koi in a pond and other objects; thousands of animated objects interacted with the user and each other on an iPad Air screen.

A Mac Pro in your pocket

Metal feature list

Another benefit of Metal is to provide developer access to the compute power of of the graphics processing unit (GPU) embedded in the A7 processor. In the right hands, this could be one of the most important aspects of Metal.

Enabling such access to the GPU means applications can be more thoroughly optimized for parallel processing.

This isn't as important to games as it is to almost everything else you do with your iPhone. Because tapping the GPU's ability to compute improves the responsiveness and potential capabilities of video, photo, and audio software, and more too.

Having powerful programmable graphics processors is one of the many reasons some software can run really fast on that black beauty, the 2013 Mac Pro, which is equipped with dual workstation graphics systems.

How'd you like to have a Mac Pro in your pocket instead?

OK, maybe I'm prone to a little hyperbole. But I'm sure you see the point.

The bottom line

Metal's yet another tool in the arsenal of game developers who are making titles for iOS. Metal is aimed at game developers looking to push the performance envelope, unlike SceneKit, another iOS 8 game technology announced at WWDC 2014 aimed more at casual game makers.

Metal will run great on the existing hardware based around an A7 processor. If you have an iPhone 5S, iPad Air or iPad mini with Retina display, you can be guaranteed it'll improve your hardcore gaming experience once iOS 8 is out in the world. Unfortunately, this leaves out users of earlier and slower devices, including the iPhone 5, 5C and older iPads and iPad minis.

For now this is a "coming soon" feature that won't be out until the fall when iOS 8 is released; some games will take advantage of it right away, while others will make the Metal migration over time. Bottom line: If gaming performance is important to you and you're using an iOS device with an older processor, start planning out your migration strategy now. And anticipate Apple will have even faster iOS gear ready later this year.

Are you a game developer or developer of another app planning on tapping into Metal? Or are you just excited about seeing the benefits as a user? Tell me what you think in the comments.

More of iOS 8: Explained

Peter Cohen
  • Really hoping this allows for huge gaming interaction between iOS and a new Apple TV!
  • it sure doesn't hurt the prospect.
  • New Apple TV would be running iOS, and hopefully Metal :)
  • Interaction is about Gameplay, and this aspect rarely gain from new GPU tech. Though better looking games for iOS devices will be possible. Current gen Apple TV though have some weaker A7 spin offs. That wont allow Apple to fight against PS4/XOne. When Apple enter any market its usually with "better than good enough" product. Apple TV as a console would not make it so. However if Metal wont make Apple Console, it surely make it closer to reality.
  • Even if they don't do gaming on the Apple TV, I'll still have it via the Playstation TV, when it comes to the US.
  • I'm trying to remember, but didn't Microsoft do sthing similar to this in relation to DirectX a while a go for desktop/laptop PCs??? (Definitely correct me if I'm wrong! lol)
  • In the sense that Microsoft is telling developers it's bringing them "closer to the metal" with DirectX 12, yes. They offered some details at the Game Developers Conference this past March.
  • As Peter replayed. However. Apple aim at christmas 2014. MS aims at christmas 2015.
    (And MS target DX11/OGL 4.4, not only OpenGL ES 3.1 level of features, tesselation, geometry, indirect rendering, content&commands generated on GPUs, etc.
    So when MS release DX12 it will be of similar abstraction level but with more feautres then current Metal, and with smaler installed base in smartphone/tablets)
  • I'm hoping a similar API to Metal replaces OpenGL on the Mac. Apple's OGL implementation is so bad and so far behind its not funny.
  • Amen, brother.
  • It do not have to be "similar" API. It just may be Metal 2.0
    (Metal API could be easily extended to support "missing" desktop-level features. By design.)
  • Flipped a goat \m/
  • I dunno.. this:
    was pretty cringe worthy.
  • I think whoever it is that maintains OpenGL (and DirectX) have gotten lazy. GPU power has increased so fast that there was basically no need to optimize those libraries. A rising tide raises all boats. But in mobile, there just isn't as much silicon real estate for all those transistors, there's far less available power, and of course no fan to cool off the GPU. So graphics framework optimization is extremely important. Glad to hear that Apple has done it. Looking past gaming, I wouldn't be surprised if Apple used Metal for other apps. Especially those that use 3d graphics like Maps. Responsiveness is a key requirement for all apps, and Metal should help greatly there. And, if Metal is easy to write to, 3rd party developers should be able to use it as well. (I've heard that OpenGL is a nightmare to code, especially if you're just starting out with it.)
  • Google "AZDO" for current OpenGL developments. Only problem is that those areny available for mobile. And also OpenGL is not hard when targeting, single mobile GPU. (Though, Apple may and should develop some głód tools around Metal for 3D devs)
  • What a great screen grab. I can see Craig speeding down the freeway in a convertible while Slayer is tearing through his speakers at full volume. Sent from the iMore App
  • I'm willing to bet that Android smartphone manufacturers will come up with something just as good if not better soon after Apple brings Metal to its own platform and it will probably be a far cheaper solution. Apple can never stay ahead for very long. I'm sure Qualcomm and NVidia are working on the same sort of thing with Google's Android. All those companies are thick as thieves in trying to make Apple appear incompetent and behind. As soon as they see Apple do it, they'll follow with something that's very similar. In the smartphone industry, nothing stays proprietary for very long. I'm pretty sure some Android manufacturer is going announce some coding product that says it runs graphics faster than Apple's Metal.