Metal iOS gives compile error

Question

import UIKit
import Metal
import QuartzCore

class ViewController: UIViewController {

var device: MTLDevice! = nil
var metalLayer: CAMetalLayer! = nil

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    device = MTLCreateSystemDefaultDevice()
    metalLayer = CAMetalLayer()          // 1
    metalLayer.device = device           // 2
    metalLayer.pixelFormat = .BGRA8Unorm // 3
    metalLayer.framebufferOnly = true    // 4
    metalLayer.frame = view.layer.frame  // 5
    view.layer.addSublayer(metalLayer)   // 6
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

When I have this in my ViewController.swift, I get the error "Use of undeclared type CAMetalLayer" even though I've imported Metal and QuartzCore. How can I get this code to work?

Rhythmic Fistman · Accepted Answer · 2019-06-04T08:19:02.977

58

UPDATE:
Simulator support is coming this year (2019)

Pre Xcode 11/iOS 13:
Metal code doesn't compile on the Simulator. Try compiling for a device.

edited Jun 04 '19 at 08:19

answered Oct 03 '15 at 23:11

Rhythmic Fistman

34,352
5
87
159

I haven't even compiled for anything yet. This shows up right after I type that stuff in and just wait – Pocketkid2 Oct 04 '15 at 03:21
2

Try selecting a device instead of the simulator in Xcode – Rhythmic Fistman Oct 04 '15 at 03:21
3

This response doesn't answer the question, because there was no question, however it is a solution to the stated problem: the Simulator can't compile metal code. If you select a Device, the compile errors go away. – Rhythmic Fistman Oct 04 '15 at 11:15
1

There is the implicit "How to fix it" question if you make a little effort. – Rivera Nov 02 '15 at 14:14
In 2017, Metal code compiles on the simulator. This person followed an online tutorial, which I also do. I get the same error. The Metal game template compiles and run on the simulator, but the code doesn't keep CAMetalLayer in it. Edit: CAMetalLayer is one of the classes not defined for the simulator. – Andreas is moving to Codidact Aug 12 '17 at 17:09
I can't find `CAMetalDrawable` on the simulator (Xcode 8.3.3, osX 10.12). Anyone tried Xcode 9? – Rhythmic Fistman Aug 12 '17 at 22:55
1

Is there any option to silent this error while i am building in simulator? – souvickcse Jan 31 '18 at 13:51
1

@souvickcse , with Metal, *there is no simulator*. You must tether a device, end of story ! That's the deal! I guess they really mean it with "Metal" :) – Fattie Dec 02 '18 at 10:35
My god how utterly retarded. Why bother shipping a simulator at all? – Reuben Scratton Dec 29 '18 at 00:54
I know. In some cases for me it was worth writing a low fidelity OpenGL codepath _just_ to keep the simulator working, but now it's deprecated... – Rhythmic Fistman Dec 29 '18 at 01:02
Yay. I just upgraded to macOS10.15beta4 + Xcode11beta4. Now the simulator can run my iOS Metal app!!! – neoneye Jul 23 '19 at 20:15
Are you importing `QuartzCore`? – Rhythmic Fistman Jun 09 '20 at 16:10

score 2 · Answer 2 · answered Apr 04 '19 at 09:48

If your app has a fallback or mode that doesn't depend on Metal, and you want to compile your app for the simulator, you can do something like this:

#if targetEnvironment(simulator)
// dummy, do-nothing view controller for simulator
class ViewController: UIViewController {

}
#else
class ViewController: UIViewController {

    var device: MTLDevice! = nil
    var metalLayer: CAMetalLayer! = nil

    override func viewDidLoad() {
        super.viewDidLoad()
        device = MTLCreateSystemDefaultDevice()
        metalLayer = CAMetalLayer()
        ...
    }

}
#endif

Then your code will at least compile for both device and simulator, which can ease your non-Metal development.

score 0 · Answer 3 · answered Sep 05 '19 at 06:29

0

The same problem may appear if you name your XCode project "Metal".

In that case compiler will be confused and you'll receive the same error message.

answered Sep 05 '19 at 06:29

fewlinesofcode

3,007
1
13
30

I doubt you get the same error as the OP has stated? – trojanfoe Sep 06 '19 at 09:06
@trojanfoe you can easily recheck it. Error is exactly the same – fewlinesofcode Sep 06 '19 at 09:08

Metal iOS gives compile error

3 Answers3