How to flip an image on an iPhone running iOS 16? Quick & easy guide inside

import UIKit

import Metal

class FlipView: UIView {

@IBOutlet weak var imageView: UIImageView!

var metalLayer: CAMetalLayer?

var renderer: MTLRenderPass?

override func draw(_ rect: CGRect) {

    super.draw(rect)

guard let originalImage UIImage(named: “originalImage.jpg”) else { return }

let imageData originalImage.cgImage!

let imageRect CGRect(x: 0, y: 0, width: imageData.width, height: imageData.height)

    // Create a Metal device and renderer

if let metalLayer CAMetalLayer() {

metalLayer.frame rect

        metalLayer.device  MTLCreateSystemDefaultDevice().makeObject(forKeyPath: kCFAllocatorDefaultNameKeyPath) as! MTLDevice
        metalLayer.pixelFormat  MTLPixelFormat.default().makeObject(forKeyPath: kCFAllocatorDefaultNameKeyPath) as! MTLPixelFormat

        // Create a Metal render pass and draw our image as a texture on the screen

guard let renderer MTLRenderPassCreate() else { return }

renderer.colorAttachments[0].loadAction .clear

renderer.colorAttachments[0].clearColor MTLClearColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

        renderer.presentation.framebufferOnly  true

guard let commandQueue metalLayer.device?.makeCommandQueue() else { return }

let commandBuffer commandQueue?.makeCommandBuffer()!

let renderEncoder commandBuffer.makeRenderCommandEncoder(description: “Flip view”)

        // Flip the image using a custom Metal function
        flipImage(imageData, renderEncoder: renderEncoder)

        // Present the render pass on the metal layer

metalLayer.presentation.framebufferOnly false

commandBuffer.commit()

    }
}

}

class FlipViewController: UIViewController {

@IBOutlet weak var flipView: FlipView!

override func viewDidLoad() {

super.viewDidLoad()

    // Create a Metal device and renderer

if let metalLayer CAMetalLayer() {

metalLayer.frame view.bounds

        view.layer.addSublayer(metalLayer)

guard let renderer MTLRenderPassCreate() else { return }

renderer.colorAttachments[0].loadAction .clear

renderer.colorAttachments[0].clearColor MTLClearColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

        renderer.presentation.framebufferOnly  true

guard let commandQueue metalLayer.device?.makeCommandQueue() else { return }

let commandBuffer commandQueue?.makeCommandBuffer()!

let renderEncoder commandBuffer.makeRenderCommandEncoder(description: “Flip view”)

        // Flip the image using a custom Metal function
        flipImage(imageData, renderEncoder: renderEncoder)

        // Present the render pass on the metal layer

metalLayer.presentation.framebufferOnly false

commandBuffer.commit()

    }
}

func flipImage(_ imageData: CVPixelBuffer, renderEncoder: MTLRenderCommandEncoder) {

    // Create a Metal sampler and set the texture coordinates

let samplerState MTLSamplerState(textureCoordinate: .uv, filter: .linear)

let sampler MTLSamplerCreate(samplerState)!

    // Create a Metal render pass descriptor

guard let renderPassDescriptor MTLOcclusionQueryRenderPassDescriptor() else { return }

    // Set the render pass descriptor's color attachment and create a Metal render pass

renderPassDescriptor.colorAttachments[0].loadAction .clear

renderPassDescriptor.colorAttachments[0].clearColor MTLClearColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

renderPassDescriptor.presentation.framebufferOnly true

    guard let renderPass  MTLRenderPassCreate(device: metalLayer?.device, descriptor: renderPassDescriptor) else { return }

    // Create a Metal drawable and set the render pass
    let drawable  MTLDrawable(pixelFormat: imageData.pixelFormat, width: imageData.width, height: imageData.height, options: [])

renderPass?.addDrawable(drawable)

    // Create a Metal command group and add the render pass to it

guard let commandGroup metalLayer?.device?.makeCommandGroup() else { return }

let drawCommand metalLayer?.device?.makeDrawCommandEncoder()!

drawCommand.renderPass renderPass

drawCommand.drawable drawable

    // Create a Metal command buffer and add the draw command to it

let commandBuffer commandGroup.makeCommandBuffer()!

drawCommand.encodeDrawable(drawable, on: commandBuffer)

    // Flip the image using a custom Metal function

renderEncoder.setRenderPass(renderPass, index: 0)

    renderEncoder.drawPrimitives(type: .triangles, indexBuffer: metalLayer?.device?.makeIndexBuffer()!.makeObject(forKeyPath: kCFAllocatorDefaultNameKeyPath) as! MTLIndexBuffer, indexCount: 6, indexBufferOffset: 0, indexBufferBindBase: 0, indexVertexType: .uint16, indexVertexOffset: 0, indexVertexCount: 3 * 2, indexVertexStride: 4 * sizeof(UInt16))

    // Present the render pass on the metal layer

commandGroup.present(commandBuffer)

    commandBuffer.commit()
}

}