How to use UnsafeMutableRawPointer to fill an array?

Question

I have a Metal texture, I want to access its data from Swift by making it a float4 array (so that I can access each pixel 4 color components).

I discovered this method

Answer 1

Another option is to create an array of the appropriate size and pass the address to the underlying storage to the function:

var pixelData = Array(repeating: float4(), count: myTextureSizeInFloat4)
pixelData.withUnsafeMutableBytes {
    texture.getBytes($0.baseAddress!, ...)
}

Inside the closure, $0 is a UnsafeMutableRawBufferPointer representing the array storage as a collection of bytes, and $0.baseAddress is a pointer to the first byte.