ios - 如何将实时相机预览添加到 UIView

Question

我遇到了一个问题，我试图在 UIView 边界内解决，是否有任何方法可以将相机预览添加到 UIView？并在 UIView 之上添加其他内容(按钮、标签等)？

我尝试使用 AVFoundation 框架，但没有足够的 Swift 文档。

Answer 1

更新到 SWIFT 5

你可以尝试这样的事情:

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()
    }

}

在这里，我使用名为 previewView 的 UIView 来启动相机，然后我在 previewView 上方添加了一个名为 boxView 的新 UIView。我将 UIButton 添加到 boxView

IMPORTANT

Remember that in iOS 10 and later you need to first ask the user for permission in order to have access to the camera. You do this by adding a usage key to your app’s Info.plist together with a purpose string because if you fail to declare the usage, your app will crash when it first makes the access.

这是显示相机访问请求的屏幕截图