How to switch cameras during recording [duplicate] - ios

Question

Using this tutorial here: http://www.musicalgeometry.com/?p=1297 I have created a custom overlay and image capture with AVCaptureSession.
I am attempting to allow the user to switch between the front and back camera. Here is my code in CaptureSessionManager to switch cameras:
- (void)addVideoInputFrontCamera:(BOOL)front {
NSArray *devices = [AVCaptureDevice devices];
AVCaptureDevice *frontCamera;
AVCaptureDevice *backCamera;
for (AVCaptureDevice *device in devices) {
//NSLog(#"Device name: %#", [device localizedName]);
if ([device hasMediaType:AVMediaTypeVideo]) {
if ([device position] == AVCaptureDevicePositionBack) {
//NSLog(#"Device position : back");
backCamera = device;
}
else {
//NSLog(#"Device position : front");
frontCamera = device;
}
}
}
NSError *error = nil;
if (front) {
AVCaptureDeviceInput *frontFacingCameraDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:frontCamera error:&error];
if (!error) {
if ([[self captureSession] canAddInput:frontFacingCameraDeviceInput]) {
[[self captureSession] addInput:frontFacingCameraDeviceInput];
} else {
NSLog(#"Couldn't add front facing video input");
}
}
} else {
AVCaptureDeviceInput *backFacingCameraDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:backCamera error:&error];
if (!error) {
if ([[self captureSession] canAddInput:backFacingCameraDeviceInput]) {
[[self captureSession] addInput:backFacingCameraDeviceInput];
} else {
NSLog(#"Couldn't add back facing video input");
}
}
}
}
Now in my custom overlay controller I initialize everything like so in viewDidLoad:
[self setCaptureManager:[[CaptureSessionManager alloc] init]];
[[self captureManager] addVideoInputFrontCamera:NO]; // set to YES for Front Camera, No for Back camera
[[self captureManager] addStillImageOutput];
[[self captureManager] addVideoPreviewLayer];
CGRect layerRect = [[[self view] layer] bounds];
[[[self captureManager] previewLayer] setBounds:layerRect];
[[[self captureManager] previewLayer] setPosition:CGPointMake(CGRectGetMidX(layerRect),CGRectGetMidY(layerRect))];
[[[self view] layer] addSublayer:[[self captureManager] previewLayer]];
[[_captureManager captureSession] startRunning];
The switch camera button is connected to a method called switchCamera. I have tried this:
- (void)switchCameraView:(id)sender {
[[self captureManager] addVideoInputFrontCamera:YES]; // set to YES for Front Camera, No for Back camera
}
When calling this, I get the error NSLog from the CaptureSessionManager and I cannot figure out why. In viewDidLoad, if I set the fontCamera to YES, it shows the front camera but cannot switch to back, and vice versa.
Any ideas on how to get it to switch properly?

Answer 1

You first need to remove the existing AVCameraInput from the AVCaptureSession and then add a new AVCameraInput to the AVCaptureSession. The following works for me (under ARC):
-(IBAction)switchCameraTapped:(id)sender
{
//Change camera source
if(_captureSession)
{
//Indicate that some changes will be made to the session
[_captureSession beginConfiguration];
//Remove existing input
AVCaptureInput* currentCameraInput = [_captureSession.inputs objectAtIndex:0];
[_captureSession removeInput:currentCameraInput];
//Get new input
AVCaptureDevice *newCamera = nil;
if(((AVCaptureDeviceInput*)currentCameraInput).device.position == AVCaptureDevicePositionBack)
{
newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront];
}
else
{
newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack];
}
//Add input to session
NSError *err = nil;
AVCaptureDeviceInput *newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:newCamera error:&err];
if(!newVideoInput || err)
{
NSLog(#"Error creating capture device input: %#", err.localizedDescription);
}
else
{
[_captureSession addInput:newVideoInput];
}
//Commit all the configuration changes at once
[_captureSession commitConfiguration];
}
}
// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
- (AVCaptureDevice *) cameraWithPosition:(AVCaptureDevicePosition) position
{
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *device in devices)
{
if ([device position] == position) return device;
}
return nil;
}

Answer 2

Swift 4/5
#IBAction func switchCameraTapped(sender: Any) {
//Change camera source
if let session = captureSession {
//Remove existing input
guard let currentCameraInput: AVCaptureInput = session.inputs.first else {
return
}
//Indicate that some changes will be made to the session
session.beginConfiguration()
session.removeInput(currentCameraInput)
//Get new input
var newCamera: AVCaptureDevice! = nil
if let input = currentCameraInput as? AVCaptureDeviceInput {
if (input.device.position == .back) {
newCamera = cameraWithPosition(position: .front)
} else {
newCamera = cameraWithPosition(position: .back)
}
}
//Add input to session
var err: NSError?
var newVideoInput: AVCaptureDeviceInput!
do {
newVideoInput = try AVCaptureDeviceInput(device: newCamera)
} catch let err1 as NSError {
err = err1
newVideoInput = nil
}
if newVideoInput == nil || err != nil {
print("Error creating capture device input: \(err?.localizedDescription)")
} else {
session.addInput(newVideoInput)
}
//Commit all the configuration changes at once
session.commitConfiguration()
}
}
// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(position: AVCaptureDevice.Position) -> AVCaptureDevice? {
let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .unspecified)
for device in discoverySession.devices {
if device.position == position {
return device
}
}
return nil
}
Swift 3 Edit (Combined with François-Julien Alcaraz answer):
#IBAction func switchCameraTapped(sender: Any) {
//Change camera source
if let session = captureSession {
//Indicate that some changes will be made to the session
session.beginConfiguration()
//Remove existing input
guard let currentCameraInput: AVCaptureInput = session.inputs.first as? AVCaptureInput else {
return
}
session.removeInput(currentCameraInput)
//Get new input
var newCamera: AVCaptureDevice! = nil
if let input = currentCameraInput as? AVCaptureDeviceInput {
if (input.device.position == .back) {
newCamera = cameraWithPosition(position: .front)
} else {
newCamera = cameraWithPosition(position: .back)
}
}
//Add input to session
var err: NSError?
var newVideoInput: AVCaptureDeviceInput!
do {
newVideoInput = try AVCaptureDeviceInput(device: newCamera)
} catch let err1 as NSError {
err = err1
newVideoInput = nil
}
if newVideoInput == nil || err != nil {
print("Error creating capture device input: \(err?.localizedDescription)")
} else {
session.addInput(newVideoInput)
}
//Commit all the configuration changes at once
session.commitConfiguration()
}
}
// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(position: AVCaptureDevicePosition) -> AVCaptureDevice? {
if let discoverySession = AVCaptureDeviceDiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaTypeVideo, position: .unspecified) {
for device in discoverySession.devices {
if device.position == position {
return device
}
}
}
return nil
}
Swift version to #NES_4Life's answer:
#IBAction func switchCameraTapped(sender: AnyObject) {
//Change camera source
if let session = captureSession {
//Indicate that some changes will be made to the session
session.beginConfiguration()
//Remove existing input
let currentCameraInput:AVCaptureInput = session.inputs.first as! AVCaptureInput
session.removeInput(currentCameraInput)
//Get new input
var newCamera:AVCaptureDevice! = nil
if let input = currentCameraInput as? AVCaptureDeviceInput {
if (input.device.position == .Back)
{
newCamera = cameraWithPosition(.Front)
}
else
{
newCamera = cameraWithPosition(.Back)
}
}
//Add input to session
var err: NSError?
var newVideoInput: AVCaptureDeviceInput!
do {
newVideoInput = try AVCaptureDeviceInput(device: newCamera)
} catch let err1 as NSError {
err = err1
newVideoInput = nil
}
if(newVideoInput == nil || err != nil)
{
print("Error creating capture device input: \(err!.localizedDescription)")
}
else
{
session.addInput(newVideoInput)
}
//Commit all the configuration changes at once
session.commitConfiguration()
}
}
// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(position: AVCaptureDevicePosition) -> AVCaptureDevice?
{
let devices = AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo)
for device in devices {
let device = device as! AVCaptureDevice
if device.position == position {
return device
}
}
return nil
}

Answer 3

Based on previous answers I made my own version with some validations and one specific change, the current camera input might not be the first object of the capture session's inputs, so I changed this:
//Remove existing input
AVCaptureInput* currentCameraInput = [self.captureSession.inputs objectAtIndex:0];
[self.captureSession removeInput:currentCameraInput];
To this (removing all video type inputs):
for (AVCaptureDeviceInput *input in self.captureSession.inputs) {
if ([input.device hasMediaType:AVMediaTypeVideo]) {
[self.captureSession removeInput:input];
break;
}
}
Here's the entire code:
if (!self.captureSession) return;
[self.captureSession beginConfiguration];
AVCaptureDeviceInput *currentCameraInput;
// Remove current (video) input
for (AVCaptureDeviceInput *input in self.captureSession.inputs) {
if ([input.device hasMediaType:AVMediaTypeVideo]) {
[self.captureSession removeInput:input];
currentCameraInput = input;
break;
}
}
if (!currentCameraInput) return;
// Switch device position
AVCaptureDevicePosition captureDevicePosition = AVCaptureDevicePositionUnspecified;
if (currentCameraInput.device.position == AVCaptureDevicePositionBack) {
captureDevicePosition = AVCaptureDevicePositionFront;
} else {
captureDevicePosition = AVCaptureDevicePositionBack;
}
// Select new camera
AVCaptureDevice *newCamera;
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *captureDevice in devices) {
if (captureDevice.position == captureDevicePosition) {
newCamera = captureDevice;
}
}
if (!newCamera) return;
// Add new camera input
NSError *error;
AVCaptureDeviceInput *newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:newCamera error:&error];
if (!error && [self.captureSession canAddInput:newVideoInput]) {
[self.captureSession addInput:newVideoInput];
}
[self.captureSession commitConfiguration];

Answer 4

Swift 3
func switchCamera() {
session?.beginConfiguration()
let currentInput = session?.inputs.first as? AVCaptureDeviceInput
session?.removeInput(currentInput)
let newCameraDevice = currentInput?.device.position == .back ? getCamera(with: .front) : getCamera(with: .back)
let newVideoInput = try? AVCaptureDeviceInput(device: newCameraDevice)
session?.addInput(newVideoInput)
session?.commitConfiguration()
}
// MARK: - Private
extension CameraService {
func getCamera(with position: AVCaptureDevicePosition) -> AVCaptureDevice? {
guard let devices = AVCaptureDevice.devices(withMediaType: AVMediaTypeVideo) as? [AVCaptureDevice] else {
return nil
}
return devices.filter {
$0.position == position
}.first
}
}
Swift 4
You can check full implementation in this gist

Answer 5

Here is an updated version of chengsam's code that includes the fix for 'Multiple audio/video AVCaptureInputs are not currently supported'.
func switchCameraTapped() {
//Change camera source
//Indicate that some changes will be made to the session
session.beginConfiguration()
//Remove existing input
guard let currentCameraInput: AVCaptureInput = session.inputs.first else {
return
}
//Get new input
var newCamera: AVCaptureDevice! = nil
if let input = currentCameraInput as? AVCaptureDeviceInput {
if (input.device.position == .back) {
newCamera = cameraWithPosition(position: .front)
} else {
newCamera = cameraWithPosition(position: .back)
}
}
//Add input to session
var err: NSError?
var newVideoInput: AVCaptureDeviceInput!
do {
newVideoInput = try AVCaptureDeviceInput(device: newCamera)
} catch let err1 as NSError {
err = err1
newVideoInput = nil
}
if let inputs = session.inputs as? [AVCaptureDeviceInput] {
for input in inputs {
session.removeInput(input)
}
}
if newVideoInput == nil || err != nil {
print("Error creating capture device input: \(err?.localizedDescription)")
} else {
session.addInput(newVideoInput)
}
//Commit all the configuration changes at once
session.commitConfiguration()
}
// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(position: AVCaptureDevice.Position) -> AVCaptureDevice? {
let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .unspecified)
for device in discoverySession.devices {
if device.position == position {
return device
}
}
return nil
}

Answer 6

Swift 3 version of cameraWithPosition without deprecated warning :
// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(_ position: AVCaptureDevicePosition) -> AVCaptureDevice?
{
if let deviceDescoverySession = AVCaptureDeviceDiscoverySession.init(deviceTypes: [AVCaptureDeviceType.builtInWideAngleCamera],
mediaType: AVMediaTypeVideo,
position: AVCaptureDevicePosition.unspecified) {
for device in deviceDescoverySession.devices {
if device.position == position {
return device
}
}
}
return nil
}
If you want, you can also get the new devicesTypes from iPhone 7+ (dual camera) by changing the deviceTypes array.
Here's a good read : https://forums.developer.apple.com/thread/63347