iOS測試IPv6環境

 簡述：分享Mac的WiFi給手機。打開分享時，需按住Option，分享才會有NAT64。

詳細方法，參考這篇的Test for IPv6 DNS64/NAT64 Compatibility Regularly。

值得注意，用USB線分享的話，會是IPv4+IPv6

Swift Decodable 找不到key時，使用預設值

使用JSONDecoder時，如果找不到Key值，錯誤如下

▿ DecodingError
  ▿ keyNotFound : 2 elements
    - .0 : CodingKeys(stringValue: "b", intValue: nil)
    ▿ .1 : Context
      - codingPath : 0 elements
      - debugDescription : "No value associated with key CodingKeys(stringValue: \"b\", intValue: nil) (\"b\")."
      - underlyingError : nil

其實只要利用KeyedDecodingContainer的decode(type:forKey)就可以解決這問題

protocol Init {
    init()
}

extension KeyedDecodingContainer {
    func decode<T: Codable & Init>(_ type: T.Type,
                forKey key: Key) throws -> T {
        try decodeIfPresent(type, forKey: key) ?? .init()
    }
}

之後只要將Codable後面，加上Init這個protocal就可以了

enum B: Int, Codable {
    case one = 1
    case two = 2
}


extension B: Init {
    init() {
        self = .one
    }
}

用swift讀寫NTag

1. 在info.plist中，加入Privacy - NFC Scan Usage Description
2. 在Capabilities 加入Near Field Communication Tag Reading
   
3. 掃描

   func startScan() {

           let session = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)

           session.alertMessage = "Hold your iPhone near an NFC transit card."

           session.begin()

   }

4. 連線，更新payload

   func readerSession(_ session: NFCNDEFReaderSession, didDetect tags: [NFCNDEFTag]) {

       guard

           let sms = "場所代碼：111111111111111 本次實聯簡訊限防疫目的使用。".addingPercentEncoding(withAllowedCharacters: .urlHostAllowed),

           let payload = NFCNDEFPayload.wellKnownTypeURIPayload(string: "sms:1922&body=\(sms)"),

           let tag = tags.first

       else {

           session.invalidate(errorMessage: "Could not process tag.")

           return

       }

       session.connect(to: tag) { error in

           guard error == nil else {

               session.invalidate(errorMessage: "Could not connect to tag.")

               return

           }

           tag.queryNDEFStatus { status, capacity, error in

               guard error == nil else {

                   session.invalidate(errorMessage: "Could not query status of tag.")

                   return

               }

               

               switch status {

               case .notSupported:

                   session.invalidate(errorMessage: "Tag is not supported.")

               case .readOnly:

                   session.invalidate(errorMessage: "Tag is only readable.")

               case .readWrite:

                   let messge = NFCNDEFMessage.init(records: [payload])

                   tag.writeNDEF(messge) { error in

                       if error != nil {

                           session.invalidate(errorMessage: "Failed to write message.")

                       } else {

                           session.alertMessage = "Successfully configured tag."

                           session.invalidate()

                       }

                   }

                   

               @unknown default:   session.invalidate(errorMessage: "Unknown status of tag.")

               }

           }

       }

   }

PS.找不到 Near Field Communication Tag Reading ，請切換開發者帳號到付費帳號

ARKit(SpriteKit) 臉部角度追蹤

1. 建立😘 。由於前鏡頭左右相反，所以X軸要反向。

   let labelNode = SKLabelNode(text: "😘")

   labelNode.horizontalAlignmentMode = .center

   labelNode.verticalAlignmentMode = .center

   labelNode.xScale = -1

2. 須將😘放入SKTransformNode，做後續的3D轉換。
   

   let face = SKTransformNode()

   face.addChild(labelNode)

   self.face = face

3. 更新時，SKTransformNode再依據ARFaceAnchor旋轉
   

   let rotate = faceAnchor.transform.rotate

   face?.setRotationMatrix(rotate)

4. 最後，記得將node轉回來，否則貼圖會是反的

完整程式

ARKit(SceneKit) 更新模型臉部表情

ARKit(SceneKit) 臉部貼圖

1. 修改Tracking and Visualizing Faces範例中的貼圖『wireframeTexture.png』
2. 指定ARSCNFaceGeometry的貼圖

   faceMesh?.firstMaterial?.diffuse.contents = UIImage(named: "wireframeTexture")

ARKit(SceneKit) 臉部表情追蹤

1.  建立臉部追蹤

// Create a session configuration

 let configuration = ARFaceTrackingConfiguration()

// Run the view's session

sceneView.session.run(configuration)

2.  建立臉部模型

func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {

    if anchor is ARFaceAnchor {

        let faceMesh = ARSCNFaceGeometry(device: sceneView.device!)

        faceMesh?.firstMaterial?.lightingModel = .physicallyBased

        let node = SCNNode(geometry: faceMesh)

        return node

    } else {

        return nil

    }

}

3.  更新臉部表情

func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {

    if let faceAnchor = anchor as? ARFaceAnchor, let faceGeometry = node.geometry as? ARSCNFaceGeometry {

        faceGeometry.update(from: faceAnchor.geometry)

    }

}