AVFoundation 来看看 Day 19

在第17天，做了一个ISBN 查询 书本的书名、书本描述

那麽今天我希望做一个使用拍照扫描辨识出ISBN码，这样就不用手动输入ISBN码

使用Vision套件

import Vision

主要是透过apple 发布的Vision套件来辨识

透过Vision套件来做也需要一个相机的View来使用Vision套件

今天先来使用建立相机View

使用AVFoundation套件来建立相机View

// 使用AVFoundation建立相机View
import AVFoundation

• AVCaptureSession：AVFoundation的核心，用来Capture跟Coordinate Data flow
• AVCaptureDevice：获得硬体设备
• AVCapturePhotoOutput: Photo的输出
• AVCaptureVideoPreviewLayer：Preview的Layer

使用的三个func来建构

• checkPermission()：来确保相机都是可以使用的
• ConfigLiveView()：来设定好相机以及资料流
• addButton()：新增拍摄Button进入View

func checkPermission(){
	let mediaType = AVMediaType.video
	// authorizationStatus回传一个常数看是否能够使用某个(mediaType)类型
	let status = AVCaptureDevice.authorizationStatus(for: mediaType)
	
	switch status{
		case .denied,.restricted:
			// 如果不能使用，则会出现提示来要求权限
			let Noauthorized = UIAlertController(title:"Error", message: "", preferredstyle: .alert)
			Noauthorized.addAction(UIAlertAction(title:"Set", style: .default){
							let setting = URL(string:UIApplication.openSettingsURLString)!
							UIApplication.shared.open(setting)
							}
		default:
			break

		}

}

ConfigLiveView(){

func ConfigLiveView(){
	// 最重要的部分，Session负责管理Capture & DataFlow
	captureSession = AVCaptureSession()
	// 规范Capture的资料要是什麽解析度
	captureSession.sessionPresent = .hd1920x1080

	// 开始Capture Device 
	// 使用DiscoverySession来将符合资料的Device资料储存
	let deviceDiscoverySession = AVCaptureDevice.DiscoverytSession(deviceTypes:[AVCaptureDevice.DeviceType.builtInDualCamera],mediaType:AVMediaType.video, position: .back)
	
	// 所有符合资料的Device
	let devices = deviceDiscoverySession.devices
	for device in devices{
		if device.position == AVCaptureDevice.Postion.back{
				// 将符合资料的储存进backCamera内
				backCamera = device
		}
	}

// 设定Input & Output
	do{
		// 让AVCaptureDeviceInput类的资料为backCamera储存至captureDeviceInput
		let captureDeviceInput = try AVCaptureDeviceInput(device:backCamera)
		captureSession.addInput(captureDeviceInput)
		}catch{
			showAlert(withTitle:"Camera Error")
			return
		}
	catureOutput = AVCapturePhotoOutput()
	// 设定好拍摄设定
	captureOutput?.setPreparedPhotoSettingsArray([AVCapturePhotoSetting(format:[AVVideoCodeKey:AVVideoCodecType.jpeg)
	captureSession.addOuptut(captureOutput!)

// 增加Preview Layer
	cameraPreviewLayer = AVCaptureVideoPreviewLayer(session:captureSession)
	cameraPreviewLayer?.videoGravity = .resizeAspectFill
	cameraPreviewLayer?.connection.videoOrientation = .portrait
	cameraPreviewLayer?.frame = view.frame
// The sublayer to be inserted into the current layer.
	self.view.layer.insertlayer(cameraPreviewLayer!,at:0)

	captureSession.startRunning()

}

addButton()

func addButton(){

	let width:CGFloat = 75
	let height = width
	button = UIButton(frame:CGRect(x: (view.frame.width - width)/2, y: view.frame.height - height - 32, width: width, height: height))
	button.backgroundColor = UIColor.white
	button.showsTouchWhenHighlighted = true
	button.addTarget(self,action: #selector(captureImage), for: .touchUpInside)
	view.addSubView(button)
}

captureImage() 用来Capture照片

// Capture
@objc func captureImage(){
	let setting = AVCapturePhotoSettings()
	captureOutput?.capturePhoto(with:setting, delegate: self)
}
	

showAlert() 用来作为提示用

func showAlert(withTitle: String){
	let UIAlertController(title:withTitle, message:"", preferredStyle: .alert)
	alertController.addAction(UIAlertAction(title:"OK", style: .default, handler:nil))
	present(alertController,animated:true,completion:nil)
}

参考网址：

程序码都是参考自

Github

加上了一点自己DIY的理解

iOS AVCaptureSession学习笔记(一)

Apple Developer Documentation

iOS拍照定制之AVCapturePhotoOutput

Apple Developer Documentation
Apple Developer Documentation