IOS:Swift: Video Screen Capture

Question

What is the screen device called in iOS/Swift?

When I print the devices I get

(
"<AVCaptureFigVideoDevice: 0x134d0f210 [Back Camera][com.apple.avfoundation.avcapturedevice.built-in_video:0]>",
"<AVCaptureFigVideoDevice: 0x134e0af80 [Front Camera][com.apple.avfoundation.avcapturedevice.built-in_video:1]>",
"<AVCaptureFigAudioDevice: 0x174265440 [iPad Microphone][com.apple.avfoundation.avcapturedevice.built-in_audio:0]>"
)

So where's the screen ID?

There's just too much outdated objective c code while swift is a moving target. I'm looking for a swift solution to capture video from my iPad screen and audio from built-in microphone. The audio will be a separate question.

Here is a screen grabber for OS X

https://github.com/kennyledet/SwiftCap

    // AVCaptureSession holds inputs and outputs for real-time capture
let mSession = AVCaptureSession()
let mScreenCapOutput = AVCaptureMovieFileOutput()
var mOutputPath = ""
// Just capture main display for now
let mMainDisplayId = CGMainDisplayID()

but I cannot find in the documentation the display ID, CGMainDisplayID, for an iPad...

Here is a typical solution for a camera in swift

https://github.com/bradley/iOSSwiftSimpleAVCamera

but it has too many errors and doesn't compile with iOS 8.1 or 8.2 and grabs video from camera.

func addVideoOutput() {
var rgbOutputSettings: NSDictionary = NSDictionary(object: Int(CInt(kCIFormatRGBA8)), forKey: kCVPixelBufferPixelFormatTypeKey)

    self.videoDeviceOutput = AVCaptureVideoDataOutput()

    self.videoDeviceOutput.alwaysDiscardsLateVideoFrames = true

    self.videoDeviceOutput.setSampleBufferDelegate(self, queue: self.sessionQueue)

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

https://developer.apple.com/library/ios/documentation/AudioVideo/Conceptual/AVFoundationPG/Articles/04_MediaCapture.html#//apple_ref/doc/uid/TP40010188-CH5-SW18

Apple gives an objective-c solution like this

/*
 * Create video connection
 */
AVCaptureDeviceInput *videoIn = [[AVCaptureDeviceInput alloc] initWithDevice:[self videoDeviceWithPosition:AVCaptureDevicePositionBack] error:nil];
if ([_captureSession canAddInput:videoIn])
    [_captureSession addInput:videoIn];

AVCaptureVideoDataOutput *videoOut = [[AVCaptureVideoDataOutput alloc] init];
[videoOut setAlwaysDiscardsLateVideoFrames:YES];
[videoOut setVideoSettings:@{(id)kCVPixelBufferPixelFormatTypeKey : [NSNumber numberWithInt:kCVPixelFormatType_32BGRA]}];
dispatch_queue_t videoCaptureQueue = dispatch_queue_create("Video Capture Queue", DISPATCH_QUEUE_SERIAL);
[videoOut setSampleBufferDelegate:self queue:videoCaptureQueue];

if ([_captureSession canAddOutput:videoOut])
    [_captureSession addOutput:videoOut];
_videoConnection = [videoOut connectionWithMediaType:AVMediaTypeVideo];
self.videoOrientation = _videoConnection.videoOrientation;

if([self.session canSetSessionPreset:AVCaptureSessionPreset640x480])
    [self.session setSessionPreset:AVCaptureSessionPreset640x480]; // Lower video resolution to decrease recorded movie size

return YES;
}

This should be easy.....???

Answer 1

If you want to capture the video of screen and save it, there is also an option to make a number of screenshots, and later to convert array of images to the video, not very efficient from performance standpoint though, you probably won't have 30-60 fps, but if you are ok w/ 5-20 fps you might want to take a look at this example for swift3.

Answer 2

Here is a working copy of iOSSwiftSimpleAVCamera in swift. It doesn't quite solve your problem but it is a bit of a starting point for anyone else that looks at this thread. Some of the error checking was removed from this code so be weary, it will only work on an actual device not in the simulator.

App delegate

//
//  AppDelegate.swift
//  iOSSwiftSimpleAVCamera
//
//  Created by Bradley Griffith on 7/1/14.
//  Copyright (c) 2014 Bradley Griffith. All rights reserved.
//

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func applicationDidFinishLaunching(application: UIApplication) {

    }

    func applicationWillResignActive(application: UIApplication) {
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
    }

    func applicationDidEnterBackground(application: UIApplication) {
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    }

    func applicationWillEnterForeground(application: UIApplication) {
        // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
    }

    func applicationDidBecomeActive(application: UIApplication) {
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    }

    func applicationWillTerminate(application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
        // Saves changes in the application's managed object context before the application terminates.
        self.saveContext()
    }

    func saveContext () {
        var error: NSError? = nil
        let managedObjectContext = self.managedObjectContext
        //if managedObjectContext != nil {
            if managedObjectContext.hasChanges && !managedObjectContext.save(&error) {
                // Replace this implementation with code to handle the error appropriately.
                // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                //println("Unresolved error \(error), \(error.userInfo)")
                abort()
           // &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&}
        }
    }

    // #pragma mark - Core Data stack

    // Returns the managed object context for the application.
    // If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
    var managedObjectContext: NSManagedObjectContext {
        if !(_managedObjectContext != nil) {
            let coordinator = self.persistentStoreCoordinator
            //if coordinator != nil {
                _managedObjectContext = NSManagedObjectContext()
                _managedObjectContext!.persistentStoreCoordinator = coordinator
            //&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&}
        }
        return _managedObjectContext!
    }
    var _managedObjectContext: NSManagedObjectContext? = nil

    // Returns the managed object model for the application.
    // If the model doesn't already exist, it is created from the application's model.
    var managedObjectModel: NSManagedObjectModel {
        if !(_managedObjectModel != nil) {
            let modelURL = NSBundle.mainBundle().URLForResource("iOSSwiftSimpleAVCamera", withExtension: "momd")
            _managedObjectModel = NSManagedObjectModel(contentsOfURL: modelURL!)
        }
        return _managedObjectModel!
    }
    var _managedObjectModel: NSManagedObjectModel? = nil

    // Returns the persistent store coordinator for the application.
    // If the coordinator doesn't already exist, it is created and the application's store added to it.
    var persistentStoreCoordinator: NSPersistentStoreCoordinator {
        if !(_persistentStoreCoordinator != nil) {
            let storeURL = self.applicationDocumentsDirectory.URLByAppendingPathComponent("iOSSwiftSimpleAVCamera.sqlite")
            var error: NSError? = nil
            _persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
            if _persistentStoreCoordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: storeURL, options: nil, error: &error) == nil {
                /*
                Replace this implementation with code to handle the error appropriately.

                abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

                Typical reasons for an error here include:
                * The persistent store is not accessible;
                * The schema for the persistent store is incompatible with current managed object model.
                Check the error message to determine what the actual problem was.


                If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.

                If you encounter schema incompatibility errors during development, you can reduce their frequency by:
                * Simply deleting the existing store:
                NSFileManager.defaultManager().removeItemAtURL(storeURL, error: nil)

                * Performing automatic lightweight migration by passing the following dictionary as the options parameter:
                [NSMigratePersistentStoresAutomaticallyOption: true, NSInferMappingModelAutomaticallyOption: true}

                Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.

                */
                //println("Unresolved error \(error), \(error.userInfo)")
                abort()
            }
        }
        return _persistentStoreCoordinator!
    }
    var _persistentStoreCoordinator: NSPersistentStoreCoordinator? = nil

    // #pragma mark - Application's Documents directory

    // Returns the URL to the application's Documents directory.
    var applicationDocumentsDirectory: NSURL {
        let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
        return urls[urls.endIndex-1] as! NSURL
    }

}

CameraSessionController

//
//  CameraSessionController.swift
//  iOSSwiftSimpleAVCamera
//
//  Created by Bradley Griffith on 7/1/14.
//  Copyright (c) 2014 Bradley Griffith. All rights reserved.
//


import UIKit
import AVFoundation
import CoreMedia
import CoreImage

@objc protocol CameraSessionControllerDelegate {
    optional func cameraSessionDidOutputSampleBuffer(sampleBuffer: CMSampleBuffer!)
}

class CameraSessionController: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate {

    var session: AVCaptureSession!
    var sessionQueue: dispatch_queue_t!
    var videoDeviceInput: AVCaptureDeviceInput!
    var videoDeviceOutput: AVCaptureVideoDataOutput!
    var stillImageOutput: AVCaptureStillImageOutput!
    var runtimeErrorHandlingObserver: AnyObject?
    var sessionDelegate: CameraSessionControllerDelegate?


    /* Class Methods
    ------------------------------------------*/

    class func deviceWithMediaType(mediaType: NSString, position: AVCaptureDevicePosition) -> AVCaptureDevice {
        var devices: NSArray = AVCaptureDevice.devicesWithMediaType(mediaType as String)
        var captureDevice: AVCaptureDevice = devices.firstObject as! AVCaptureDevice

        for object:AnyObject in devices {
            let device = object as! AVCaptureDevice
            if (device.position == position) {
                captureDevice = device
                break
            }
        }

        return captureDevice
    }


    /* Lifecycle
    ------------------------------------------*/

    override init() {
        super.init();

        self.session = AVCaptureSession()

        self.authorizeCamera();

        self.sessionQueue = dispatch_queue_create("CameraSessionController Session", DISPATCH_QUEUE_SERIAL)

        dispatch_async(self.sessionQueue, {
            self.session.beginConfiguration()
            self.addVideoInput()
            self.addVideoOutput()
            self.addStillImageOutput()
            self.session.commitConfiguration()
            })
    }


    /* Instance Methods
    ------------------------------------------*/

    func authorizeCamera() {
        AVCaptureDevice.requestAccessForMediaType(AVMediaTypeVideo, completionHandler: {
            (granted: Bool) -> Void in
            // If permission hasn't been granted, notify the user.
            if !granted {
                dispatch_async(dispatch_get_main_queue(), {
                    UIAlertView(
                        title: "Could not use camera!",
                        message: "This application does not have permission to use camera. Please update your privacy settings.",
                        delegate: self,
                        cancelButtonTitle: "OK").show()
                    })
            }
            });
    }

    func addVideoInput() -> Bool {
        var success: Bool = false
        var error: NSError?

        var videoDevice: AVCaptureDevice = CameraSessionController.deviceWithMediaType(AVMediaTypeVideo, position: AVCaptureDevicePosition.Back)
        self.videoDeviceInput = AVCaptureDeviceInput.deviceInputWithDevice(videoDevice, error: &error) as! AVCaptureDeviceInput;
        if !(error != nil) {
            if self.session.canAddInput(self.videoDeviceInput) {
                self.session.addInput(self.videoDeviceInput)
                success = true
            }
        }

        return success
    }

    func addVideoOutput() {
        //&&&&&&&&&&&&&&&&&&&&&var rgbOutputSettings: NSDictionary = NSDictionary(object: Int(CInt(kCIFormatRGBA8)), forKey: kCVPixelBufferPixelFormatTypeKey)

        self.videoDeviceOutput = AVCaptureVideoDataOutput()

        self.videoDeviceOutput.alwaysDiscardsLateVideoFrames = true

        self.videoDeviceOutput.setSampleBufferDelegate(self, queue: self.sessionQueue)

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

    func addStillImageOutput() {
        self.stillImageOutput = AVCaptureStillImageOutput()
        self.stillImageOutput.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]

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

    func startCamera() {
        dispatch_async(self.sessionQueue, {
            var weakSelf: CameraSessionController? = self
            self.runtimeErrorHandlingObserver = NSNotificationCenter.defaultCenter().addObserverForName(AVCaptureSessionRuntimeErrorNotification, object: self.sessionQueue, queue: nil, usingBlock: {
                (note: NSNotification!) -> Void in

                let strongSelf: CameraSessionController = weakSelf!

                dispatch_async(strongSelf.sessionQueue, {
                    strongSelf.session.startRunning()
                })
            })
            self.session.startRunning()
        })
    }

    func teardownCamera() {
        dispatch_async(self.sessionQueue, {
            self.session.stopRunning()
            NSNotificationCenter.defaultCenter().removeObserver(self.runtimeErrorHandlingObserver!)
        })
    }

    func focusAndExposeAtPoint(point: CGPoint) {
        dispatch_async(self.sessionQueue, {
            var device: AVCaptureDevice = self.videoDeviceInput.device
            var error: NSErrorPointer!

            if device.lockForConfiguration(error) {
                if device.focusPointOfInterestSupported && device.isFocusModeSupported(AVCaptureFocusMode.AutoFocus) {
                    device.focusPointOfInterest = point
                    device.focusMode = AVCaptureFocusMode.AutoFocus
                }

                if device.exposurePointOfInterestSupported && device.isExposureModeSupported(AVCaptureExposureMode.AutoExpose) {
                    device.exposurePointOfInterest = point
                    device.exposureMode = AVCaptureExposureMode.AutoExpose
                }

                device.unlockForConfiguration()
            }
            else {
                // TODO: Log error.
            }
        })
    }

    func captureImage(completion:((image: UIImage?, error: NSError?) -> Void)?) {




        if (completion != nil){
        if(self.stillImageOutput != nil) {
            return
            }}

        dispatch_async(self.sessionQueue, {

            self.stillImageOutput.captureStillImageAsynchronouslyFromConnection(self.stillImageOutput.connectionWithMediaType(AVMediaTypeVideo), completionHandler: {
                (imageDataSampleBuffer: CMSampleBuffer?, error: NSError?) -> Void in


                if (imageDataSampleBuffer != nil)
                {
                    if(error != nil)
                    {
                        completion!(image:nil, error:nil)

                    }
                }

                else if (imageDataSampleBuffer != nil) {
                    var imageData: NSData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer)
                    var image: UIImage = UIImage(data: imageData)!
                    completion!(image:image, error:nil)
                }
                })
            })
    }


    /* AVCaptureVideoDataOutput Delegate
    ------------------------------------------*/

    func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {
        self.sessionDelegate?.cameraSessionDidOutputSampleBuffer?(sampleBuffer)
    }

}

camera view controller

//
//  CameraViewController.swift
//  iOSSwiftSimpleAVCamera
//
//  Created by Bradley Griffith on 7/1/14.
//  Copyright (c) 2014 Bradley Griffith. All rights reserved.
//


import UIKit
import CoreMedia
import AVFoundation

class CameraViewController: UIViewController, CameraSessionControllerDelegate {

    var cameraSessionController: CameraSessionController!
    var previewLayer: AVCaptureVideoPreviewLayer!


    /* Lifecycle
    ------------------------------------------*/

    override func viewDidLoad() {
        super.viewDidLoad()

        self.cameraSessionController = CameraSessionController()
        self.cameraSessionController.sessionDelegate = self
        self.setupPreviewLayer()
    }

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)

        self.cameraSessionController.startCamera()
    }

    override func viewWillDisappear(animated: Bool) {
        super.viewWillDisappear(animated)

        self.cameraSessionController.teardownCamera()
    }


    /* Instance Methods
    ------------------------------------------*/

    func setupPreviewLayer() {
        var minSize = min(self.view.bounds.size.width, self.view.bounds.size.height)
        var bounds: CGRect = CGRectMake(0.0, 0.0, minSize, minSize)
        self.previewLayer = AVCaptureVideoPreviewLayer(session: self.cameraSessionController.session)
        self.previewLayer.bounds = bounds
        self.previewLayer.position = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds))
        self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill

        self.view.layer.addSublayer(self.previewLayer)
    }

    func cameraSessionDidOutputSampleBuffer(sampleBuffer: CMSampleBuffer!) {
        // Any frame processing could be done here.
    }

}