Обнаружить наличие камеры в приложении для iPhone?

Вы можете использовать метод +isSourceTypeAvailable: в UIImagePickerController:

if ([UIImagePickerController isSourceTypeAvailable: UIImagePickerControllerSourceTypeCamera])
   // Has camera

Как написал Хуан Боэро, проверьте:

    if UIImagePickerController.isSourceTypeAvailable(.camera) {...}

Но я бы добавил еще одну проверку, чтобы увидеть, разрешил ли пользователь доступ к камере, как предлагает Apple в своем примере PhotoPicker (Пример PhotoPicker Objective-C):

* обратите внимание, что вам необходимо импортировать AVFoundation

SWIFT 5

    let authStatus = AVCaptureDevice.authorizationStatus(for: AVMediaType.video)
    switch authStatus {
        /*
         Status Restricted -
         The client is not authorized to access the hardware for the media type. The user cannot change the client's status, possibly due to active restrictions such as parental controls being in place.
         */
    case .denied, .restricted:
        // Denied access to camera
        // Explain that we need camera access and how to change it.
        let dialog = UIAlertController(title: "Unable to access the Camera", message: "To enable access, go to Settings > Privacy > Camera and turn on Camera access for this app.", preferredStyle: UIAlertController.Style.alert)

        let okAction = UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil)

        dialog.addAction(okAction)
        self.present(dialog, animated:true, completion:nil)
    case .notDetermined:
        // The user has not yet been presented with the option to grant access to the camera hardware.
        // Ask for it.
        AVCaptureDevice.requestAccess(for: AVMediaType.video, completionHandler: { (grantd) in
        // If access was denied, we do not set the setup error message since access was just denied.
           if grantd {
           // Allowed access to camera, go ahead and present the UIImagePickerController.
            self.showImagePickerForSourceType(sourceType: UIImagePickerController.SourceType.camera)
            }
        })
    case .authorized:
        // Allowed access to camera, go ahead and present the UIImagePickerController.
        self.showImagePickerForSourceType(sourceType: UIImagePickerController.SourceType.camera)
    @unknown default:
        break; //handle other status
    }

SWIFT 3

let authStatus = AVCaptureDevice.authorizationStatus(forMediaType: AVMediaTypeVideo)
    
if authStatus == AVAuthorizationStatus.denied {
    // Denied access to camera
    // Explain that we need camera access and how to change it.
    let dialog = UIAlertController(title: "Unable to access the Camera", message: "To enable access, go to Settings > Privacy > Camera and turn on Camera access for this app.", preferredStyle: UIAlertControllerStyle.alert)
        
    let okAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil)
        
    dialog.addAction(okAction)
    self.present(dialog, animated:true, completion:nil)
        
} else if authStatus == AVAuthorizationStatus.notDetermined {     // The user has not yet been presented with the option to grant access to the camera hardware.
    // Ask for it.
    AVCaptureDevice.requestAccess(forMediaType: AVMediaTypeVideo, completionHandler: { (grantd) in
    // If access was denied, we do not set the setup error message since access was just denied.
       if grantd {
       // Allowed access to camera, go ahead and present the UIImagePickerController.
            self.showImagePickerForSourceType(sourceType: UIImagePickerControllerSourceType.camera)
        }
    })
} else {
        
    // Allowed access to camera, go ahead and present the UIImagePickerController.
    self.showImagePickerForSourceType(sourceType: UIImagePickerControllerSourceType.camera)

}

func showImagePickerForSourceType(sourceType: UIImagePickerControllerSourceType) {
    
    let myPickerController = UIImagePickerController()
    myPickerController.delegate = self;
    myPickerController.sourceType = sourceType  
    self.present(myPickerController, animated: true, completion: nil)
}

Если вы используете классы AV Foundation вместо UIImagePickerController, вы можете:

BOOL hasCamera = ([[AVCaptureDevice devices] count] > 0);

Если вы используете UIImagePickerController, это, вероятно, того не стоит, поскольку вам придется добавить AVFoundation.framework в свой проект.

Да, для этого есть API:

BOOL isCamera = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];

Swift:

if UIImagePickerController.isSourceTypeAvailable(.Camera){

    //Your code goes here
    //For example you can print available media types:

    print(UIImagePickerController.availableMediaTypesForSourceType(.Camera))

    }

Если вам нужно знать, есть ли у устройства конкретно передняя или задняя камера, используйте это:

isCameraAvailable = [UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront];

Доступна проверка камеры (Swift)

if(!UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera))

Вы можете проверить доступность определенного типа источника с помощью сеанса обнаружения (Swift 5):

let discovery = AVCaptureDevice.DiscoverySession.init(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .back)
let isWideAngleCameraSupported = !discovery.devices.isEmpty