How to deallocate a MTLBuffer and MTLTexture

I know how to create a MTLBuffer and or MTLTexture but how do I free the GPU memory for these resources when they are no longer needed?

Solution

MTLBuffer and MTLTexture are Objective-C objects and thus reference counted. If you are using automatic reference counting in an Objective-C project or using Metal via Swift, simply ensuring you no longer hold references to the buffer or texture will release any associated hardware resources.

let texture: MTLTexture? = device.newTexture(with: descriptor)
texture = nil // <- resources will be released

One can confirm this by stepping through the associated assembly when assigning nil to texture, which first leads us to [MTLDebugTexture dealloc]

MetalTools`-[MTLDebugTexture dealloc]:
    ...
->  0x100af569e <+34>: call   0x100af87ee               ; symbol stub for: objc_msgSendSuper2
    0x100af56a3 <+39>: add    rsp, 0x10
    0x100af56a7 <+43>: pop    rbp
    0x100af56a8 <+44>: ret

...and through [MTLToolsObject dealloc]

MetalTools`-[MTLToolsObject dealloc]:
    0x100ac6c7a <+0>:   push   rbp
    0x100ac6c7b <+1>:   mov    rbp, rsp
    0x100ac6c7e <+4>:   push   r14
    ...

...and through the GeForceMTLDriver

GeForceMTLDriver`___lldb_unnamed_symbol1095$$GeForceMTLDriver:
->  0x7fffd2e57b14 <+0>:  push   rbp
    0x7fffd2e57b15 <+1>:  mov    rbp, rsp

All the way, releasing any resources through the various dealloc methods.