Swift 3 - 自定义相机视图 - 显示按钮点击后拍摄的照片的静止图像

Question

I am using Swift 3, Xcode 8.2.

I have a custom camera view which displays the video feed fine and a button that I want to act as a shutter. When the user taps on the button, I want a picture taken and it to be displayed on the screen. (eg like a Snapchat or Facebook Messenger style camera behavior)

Here is my code:

import UIKit
import AVFoundation

class CameraVC: UIViewController, AVCapturePhotoCaptureDelegate {

   // this is where the camera feed from the phone is going to be displayed
    @IBOutlet var cameraView : UIView!

    var shutterButton : UIButton = UIButton.init(type: .custom)

    // manages capture activity and coordinates the flow of data from input devices to capture outputs.
    var capture_session = AVCaptureSession()

    // a capture output for use in workflows related to still photography.
    var session_output = AVCapturePhotoOutput()

    // preview layer that we will have on our view so users can see the photo we took
    var preview_layer = AVCaptureVideoPreviewLayer()

    // still picture image is what we show as the picture taken, frozen on the screen
    var still_picture_image : UIImage!

    ... //more code in viewWillAppear that sets up the camera feed

    // called when the shutter button is pressed
    func shutterButtonPressed() {

        // get the actual video feed and take a photo from that feed
        session_output.capturePhoto(with: AVCapturePhotoSettings.init(format: [AVVideoCodecKey : AVVideoCodecJPEG]), delegate: self as AVCapturePhotoCaptureDelegate)
    }

    func capture(_ captureOutput: AVCapturePhotoOutput, didFinishProcessingPhotoSampleBuffer photoSampleBuffer: CMSampleBuffer?, previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {

        // take the session output, get the buffer, and create an image from that buffer
        if let sampleBuffer = photoSampleBuffer,
            let previewBuffer = previewPhotoSampleBuffer,
            let imageData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: sampleBuffer, previewPhotoSampleBuffer: previewBuffer) {

            print("Here") // doesn't get here

        }

    }

It doesn't seem to print "Here" when running this code and I can't find any Swift 3 tutorials on how to display this image. I'm guessing I want to take the imageData and assign it to my still_picture_image and overlay that over the camera feed somehow.

Any help or a point in the right direction would be great help.

EDIT

After adding the following to my code:

        if let error = error {
            print(error.localizedDescription)
        }

But I still don't get any error printed.

Answer 1

Add the following code into your delegate method to print out the error being thrown:

if let error = error {
   print(error.localizedDescription)
}

Once you get your error resolved, I think this post should help you to extract the image: Taking photo with custom camera Swift 3

Answer 2

Okay, I figured out my problem:

First, drag an UIImageView to the Storyboard and have it take up the entire screen. This is where the still picture will be displayed after pressing the shutter button.

Create that variable in the code and link it.

@IBOutlet weak var stillPicture : UIImageView!

Then, in viewDidLoad make sure that you insert the UIImageView on top of the camera view.

self.view.insertSubview(stillPicture, aboveSubview: your_camera_view)

This is the function that is called when the shutter button is clicked:

func shutterButtonPressed() {

    let settings = AVCapturePhotoSettings()

    let previewPixelType = settings.availablePreviewPhotoPixelFormatTypes.first!
    let previewFormat = [kCVPixelBufferPixelFormatTypeKey as String: previewPixelType,
                         kCVPixelBufferWidthKey as String: 160,
                         kCVPixelBufferHeightKey as String: 160,
                         ]
    settings.previewPhotoFormat = previewFormat
    session_output.capturePhoto(with: settings, delegate: self)
}

Then, in your capture delegate:

func capture(_ captureOutput: AVCapturePhotoOutput, didFinishProcessingPhotoSampleBuffer photoSampleBuffer: CMSampleBuffer?, previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {
        if let error = error {
            print(error.localizedDescription)
        }

        // take the session output, get the buffer, and create an image from that buffer
        if let sampleBuffer = photoSampleBuffer, let previewBuffer = previewPhotoSampleBuffer, let dataImage = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: sampleBuffer, previewPhotoSampleBuffer: previewBuffer) {
            // this is the image that the user has taken!
            let takenImage : UIImage = UIImage(data: dataImage)!
            stillPicture?.image = takenImage                
        } else {
            print("Error setting up photo capture")
        }
}