Calling Core Foundation functions with pointer arguments

README.md

Calling Core Foundation functions with pointer arguments

Thus far, I've encountered two approaches to manage a Create/Copy memory:

• unsafe_pointer
• plain_ref

At this point, it's hard to pick the right path. Is it safe to assume their equivalence?

@nnnnnnnn kindly has confirmed viability of both methods. Though a plain_ref is somewhat superior in ergonomics.

References

• NSHipster: Unmanaged
• Apple: The Create Rule
• Apple: Calling Functions With Pointer Parameters
• Swift: UnsafeRawPointer API

Examples

• Example manages single pixel buffer via plain ref
• Example recyles pixel buffers via plain ref approach
• Example recycles pixel buffers via unmanaged pointer

CoreFoundation+PointerArguments.swift

let pixelBufferPool: CVPixelBufferPool = // ...

unsafe_pointer: do {
    let pixelBufferPointer = UnsafeMutablePointer<CVPixelBuffer?>.allocate(capacity: 1)
    
    defer {
        pixelBufferPointer.deinitialize(count: 1)
        pixelBufferPointer.deallocate()
    }
                    
    CVPixelBufferPoolCreatePixelBuffer(
        nil,
        pixelBufferPool,
        pixelBufferPointer
    )
}
    
plain_ref: do {
    var pxbuffer: CVPixelBuffer?
  
    CVPixelBufferPoolCreatePixelBuffer(
        nil,
        pixelBufferPool,
        &pxbuffer
    )
  
    pxbuffer = nil
}