build disappears

Check the Target Platform of your framework and watchkit extensiosn in their Build Settings.It seems currently Xcode 7 only lets you choose either iOS or watchOS, but since your framework is shared between platforms you need to manually put all 4 of: watchsimulator, watchos, iphonesimulator, iphoneosIn my case, after fixing the above, I also needed to add armv7k and i386 to Valid Architectures.Then I finally got to see all the new WatchKit compile errors 🙂

This sounds like a Radar to me. I am having the same issue. I had compiled this for the WatchKit Extension under iOS 8 + WK. I'm guessing there is a bit of unimplemented foo between the seed 1 release and the conference demo seed (Usually a few builds later)Work around seems to be temporarily to move that functionality over to the iOS app and WatchComm it across.

Apps are deleted/replaced when updated via the usual process. And while IAP items bought during testing are kept for store builds, TF users game in the sandbox, so....

The ability to build native standalone Watch Apps is reported to be for late summer.Xcode 7b, as an example, only offers this for new apps/projects (also frameworks/libs):This template provides a starting point for an iOS application with an associated WatchKit Application.

Yes.A central focus of Metal is to dramatically reduce the CPU cost of common operations. However, it is still quite possible for wasteful code to blow out the CPU cost and end up running slowly and eating up a bunch of battery life. That is, even though the CPU and GPU can run concurrently, your GPU frames can't cycle any faster than the CPU workload required to encode / enqueue them. Thus, quite a lot of making Metal go fast can be making sure that your CPU workload isn't consuming all your time. For me, the CPU cost is usually around 10% or less of the GPU time in well behaved code. If you are running more than that, then you may need to spend some time finding out why.Most of the time, it comes down to object reuse. It is maybe the key way to improve Metal performance. Much of Metal is designed around the assumption that you will allocate expensive resources (textures, buffers, shaders, queues) up front and then reuse them. As an application writer, this is fairly simple, since you should know in advance