Xcode does not use GPU for Swift Metal

I am wondering why Xcode uses CPU for Metal GPU shader program execution for Swift. With Objective-C Metal, it finishes instantly. But the same shader program, when called from Swift, takes many seconds. GPU is idle while CPU runs 99%. I use the following line to choose GPU in Swift. But doesn't seem to choose real GPU.

let device: MTLDevice = MTLCreateSystemDefaultDevice()!

For Objective-C, I use the same default device. This chooses GPU correctly.

MTLDevice  device = MTLCreateSystemDefaultDevice();

Is there any way I can choose GPU in Swift Metal?

Xcode does not use GPU for Swift Metal
 
 
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