如何在UIView中添加实时相机预览

Question

我遇到了一个问题，在UIView范围内尝试解决，有没有办法在UIView上添加相机预览？并且可以在UIView的顶部添加其他内容（按钮、标签等）？

我尝试使用AVFoundation框架，但是对于Swift来说，文档不够充分。

- Brian Nezhad

Answer 1

更新至 Swift 5

你可以尝试像这样做：

import UIKit
import AVFoundation

class ViewController: UIViewController{
    var previewView : UIView!
    var boxView:UIView!
    let myButton: UIButton = UIButton()

    //Camera Capture requiered properties
    var videoDataOutput: AVCaptureVideoDataOutput!
    var videoDataOutputQueue: DispatchQueue!
    var previewLayer:AVCaptureVideoPreviewLayer!
    var captureDevice : AVCaptureDevice!
    let session = AVCaptureSession()

    override func viewDidLoad() {
        super.viewDidLoad()
        previewView = UIView(frame: CGRect(x: 0,
                                           y: 0,
                                           width: UIScreen.main.bounds.size.width,
                                           height: UIScreen.main.bounds.size.height))
        previewView.contentMode = UIView.ContentMode.scaleAspectFit
        view.addSubview(previewView)

        //Add a view on top of the cameras' view
        boxView = UIView(frame: self.view.frame)

        myButton.frame = CGRect(x: 0, y: 0, width: 200, height: 40)
        myButton.backgroundColor = UIColor.red
        myButton.layer.masksToBounds = true
        myButton.setTitle("press me", for: .normal)
        myButton.setTitleColor(UIColor.white, for: .normal)
        myButton.layer.cornerRadius = 20.0
        myButton.layer.position = CGPoint(x: self.view.frame.width/2, y:200)
        myButton.addTarget(self, action: #selector(self.onClickMyButton(sender:)), for: .touchUpInside)

        view.addSubview(boxView)
        view.addSubview(myButton)

        self.setupAVCapture()
    }

    override var shouldAutorotate: Bool {
        if (UIDevice.current.orientation == UIDeviceOrientation.landscapeLeft ||
        UIDevice.current.orientation == UIDeviceOrientation.landscapeRight ||
        UIDevice.current.orientation == UIDeviceOrientation.unknown) {
            return false
        }
        else {
            return true
        }
    }

    @objc func onClickMyButton(sender: UIButton){
        print("button pressed")
    }
}


// AVCaptureVideoDataOutputSampleBufferDelegate protocol and related methods
extension ViewController:  AVCaptureVideoDataOutputSampleBufferDelegate{
     func setupAVCapture(){
        session.sessionPreset = AVCaptureSession.Preset.vga640x480
        guard let device = AVCaptureDevice
        .default(AVCaptureDevice.DeviceType.builtInWideAngleCamera, 
                 for: .video,
                 position: AVCaptureDevice.Position.back) else {
                            return
        }
        captureDevice = device
        beginSession()
    }

    func beginSession(){
        var deviceInput: AVCaptureDeviceInput!

        do {
            deviceInput = try AVCaptureDeviceInput(device: captureDevice)
            guard deviceInput != nil else {
                print("error: cant get deviceInput")
                return
            }

            if self.session.canAddInput(deviceInput){
                self.session.addInput(deviceInput)
            }

            videoDataOutput = AVCaptureVideoDataOutput()
            videoDataOutput.alwaysDiscardsLateVideoFrames=true
            videoDataOutputQueue = DispatchQueue(label: "VideoDataOutputQueue")
            videoDataOutput.setSampleBufferDelegate(self, queue:self.videoDataOutputQueue)

            if session.canAddOutput(self.videoDataOutput){
                session.addOutput(self.videoDataOutput)
            }

            videoDataOutput.connection(with: .video)?.isEnabled = true

            previewLayer = AVCaptureVideoPreviewLayer(session: self.session)
            previewLayer.videoGravity = AVLayerVideoGravity.resizeAspect

            let rootLayer :CALayer = self.previewView.layer
            rootLayer.masksToBounds=true
            previewLayer.frame = rootLayer.bounds
            rootLayer.addSublayer(self.previewLayer)
            session.startRunning()
        } catch let error as NSError {
            deviceInput = nil
            print("error: \(error.localizedDescription)")
        }
    }

    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        // do stuff here
    }

    // clean up AVCapture
    func stopCamera(){
        session.stopRunning()
    }

}

我在这里使用一个名为 previewView 的 UIView 来启动相机，然后添加了一个名为 boxView 的新的 UIView，它位于 previewView 上方。我向 boxView 中添加了一个 UIButton。

重要提示

请记住，在iOS 10及更高版本中，您需要首先请求用户权限才能访问相机。您可以通过将用途键（usage key）和目的字符串（purpose string）添加到应用程序的 Info.plist 中来实现此目的， 因为如果您未声明使用情况，您的应用程序将在第一次访问时崩溃。

以下是显示相机访问请求的屏幕截图

- mauricioconde

---

我已经 UpVote 了你的回答，它正好做我想要的事情，但我需要概述消失。 - Brian Nezhad

我该如何从CMSampleBuffer中录制电影？ - TheCesco1988

我怎样才能在同一份代码中实现全屏相机视图？ - Hardik Vyas

Answer 2

Swift 4

以下是mauricioconde方案的简化版本：

您可以将此作为组件使用：

//
//  CameraView.swift

import Foundation
import AVFoundation
import UIKit

final class CameraView: UIView {

    private lazy var videoDataOutput: AVCaptureVideoDataOutput = {
        let v = AVCaptureVideoDataOutput()
        v.alwaysDiscardsLateVideoFrames = true
        v.setSampleBufferDelegate(self, queue: videoDataOutputQueue)
        v.connection(with: .video)?.isEnabled = true
        return v
    }()

    private let videoDataOutputQueue: DispatchQueue = DispatchQueue(label: "JKVideoDataOutputQueue")
    private lazy var previewLayer: AVCaptureVideoPreviewLayer = {
        let l = AVCaptureVideoPreviewLayer(session: session)
        l.videoGravity = .resizeAspect
        return l
    }()

    private let captureDevice: AVCaptureDevice? = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back)
    private lazy var session: AVCaptureSession = {
        let s = AVCaptureSession()
        s.sessionPreset = .vga640x480
        return s
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)

        commonInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        commonInit()
    }

    private func commonInit() {
        contentMode = .scaleAspectFit
        beginSession()
    }

    private func beginSession() {
        do {
            guard let captureDevice = captureDevice else {
                fatalError("Camera doesn't work on the simulator! You have to test this on an actual device!")
            }
            let deviceInput = try AVCaptureDeviceInput(device: captureDevice)
            if session.canAddInput(deviceInput) {
                session.addInput(deviceInput)
            }

            if session.canAddOutput(videoDataOutput) {
                session.addOutput(videoDataOutput)
            }
            layer.masksToBounds = true
            layer.addSublayer(previewLayer)
            previewLayer.frame = bounds
            session.startRunning()
        } catch let error {
            debugPrint("\(self.self): \(#function) line: \(#line).  \(error.localizedDescription)")
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        previewLayer.frame = bounds
    }
}

extension CameraView: AVCaptureVideoDataOutputSampleBufferDelegate {}

- Charlton Provatas

---

有没有办法改变预览的帧率？比如慢动作预览要比普通视频预览快很多。 - sdfsdf

我如何在我添加到此视图顶部的按钮上单击时捕获图像？ - Mithilesh Parmar

你应该能够使用CoreGraphics来处理这个问题。请参考：https://dev59.com/s2855IYBdhLWcg3wcz_y#4334902 - Charlton Provatas

Answer 3

iOS 13/14和Swift 5.3:

private var imageVC: UIImagePickerController?

当你想要显示相机视图时，请调用showCameraVC()函数。

func showCameraVC() {    
    self.imageVC = UIImagePickerController()

    if UIImagePickerController.isCameraDeviceAvailable(.front) {
        self.imageVC?.sourceType = .camera
        self.imageVC?.cameraDevice = .front
        self.imageVC?.showsCameraControls = false
                
        let screenSize = UIScreen.main.bounds.size
        let cameraAspectRatio = CGFloat(4.0 / 3.0)
        let cameraImageHeight = screenSize.width * cameraAspectRatio
        let scale = screenSize.height / cameraImageHeight
        self.imageVC?.cameraViewTransform = CGAffineTransform(translationX: 0, y: (screenSize.height - cameraImageHeight)/2)
        self.imageVC?.cameraViewTransform = self.imageVC!.cameraViewTransform.scaledBy(x: scale, y: scale)
    
        self.imageVC?.view.frame = CGRect(x: 0, y: 0, width: screenSize.width, height: screenSize.height)
        self.view.addSubview(self.imageVC!.view)
        self.view.sendSubviewToBack(self.imageVC!.view)
    }
}

摄像头视图也将全屏显示（其他答案无法解决带黑边的问题）

- Radu Ursache

---

这是一个很好的解决方案，但在横屏模式下不起作用。根据苹果的UIImagePickerController文档，“UIImagePickerController类仅支持纵向模式”。 - Raz

Answer 4

Swift 3：

@IBOutlet weak var cameraContainerView:UIView!

var imagePickers:UIImagePickerController?

在ViewDidLoad方法中：

override func viewDidLoad() {

        super.viewDidLoad()
        addImagePickerToContainerView()

    }

向容器视图添加相机预览：

func addImagePickerToContainerView(){

        imagePickers = UIImagePickerController()
        if UIImagePickerController.isCameraDeviceAvailable( UIImagePickerControllerCameraDevice.front) {
            imagePickers?.delegate = self
            imagePickers?.sourceType = UIImagePickerControllerSourceType.camera

            //add as a childviewcontroller
            addChildViewController(imagePickers!)

            // Add the child's View as a subview
            self.cameraContainerView.addSubview((imagePickers?.view)!)
            imagePickers?.view.frame = cameraContainerView.bounds
            imagePickers?.allowsEditing = false
            imagePickers?.showsCameraControls = false
            imagePickers?.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]

        }
    }

关于自定义按钮操作：

@IBAction func cameraButtonPressed(_ sender: Any) {

         if UIImagePickerController.isSourceTypeAvailable(.camera){
            imagePickers?.takePicture()

         } else{

          //Camera not available.
        }  
    }

- Alvin George

---

那么如何从这个imagePickers?.takePicture()中获取捕获图像的路径并在单独的视图中显示呢？ - Hari Narayanan

Answer 5

Swift 5 简单易学

import UIKit
import AVFoundation

class ViewController: UIViewController, UINavigationControllerDelegate,UIImagePickerControllerDelegate{

//Camera Capture requiered properties
var imagePickers:UIImagePickerController?

@IBOutlet weak var customCameraView: UIView!

override func viewDidLoad() {
    addCameraInView()
    super.viewDidLoad()
}

func addCameraInView(){

    imagePickers = UIImagePickerController()
    if UIImagePickerController.isCameraDeviceAvailable( UIImagePickerController.CameraDevice.rear) {
        imagePickers?.delegate = self
        imagePickers?.sourceType = UIImagePickerController.SourceType.camera

        //add as a childviewcontroller
        addChild(imagePickers!)

        // Add the child's View as a subview
        self.customCameraView.addSubview((imagePickers?.view)!)
        imagePickers?.view.frame = customCameraView.bounds
        imagePickers?.allowsEditing = false
        imagePickers?.showsCameraControls = false
        imagePickers?.view.autoresizingMask = [.flexibleWidth,  .flexibleHeight]
        }
    }

    @IBAction func cameraButtonPressed(_ sender: Any) {

         if UIImagePickerController.isSourceTypeAvailable(.camera){
            imagePickers?.takePicture()

         } else{

          //Camera not available.
        }
    }
}

- Shakeel Ahmed

---

以下很棒。在手机上看起来很好。但是，如何控制捕获的图像？请注意，我已将上述内容添加为subView，而不是通过IB。 - David Sanford