如何使用UIImagePickerControllerDelegate在viewDidLoad上启动相机？

我有一个新的iOS应用程序在Swift中，我试图在应用程序启动后立即显示相机。 在我的视图控制器中，我有一个UIView对象，我试图用相机来填充。

我的视图控制器中的代码在viewDidLoad方法中调用UIImagePickerController ，但没有任何反应。

这里是代码，任何想法为什么没有发生？ 这个代码是不是应该在应用程序启动时打开相机？

 import UIKit class ViewController: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate { let imagePicker = UIImagePickerController() @IBOutlet weak var imageViewer: UIImageView! override func viewDidLoad() { super.viewDidLoad() if UIImagePickerController.isCameraDeviceAvailable( UIImagePickerControllerCameraDevice.Front) { imagePicker.delegate = self imagePicker.sourceType = UIImagePickerControllerSourceType.Camera presentViewController(imagePicker, animated: true, completion: nil) } else { println("no front camera available") } // Do any additional setup after loading the view, typically from a nib. } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) { dismissViewControllerAnimated(true, completion: nil) imageViewer.image = image } } 

更新 ：如果我添加一个button到故事板，连接到代码，并把viewDidLoad中的代码放在里面，相机在点击button时工作：

 @IBAction func presentImagePicker(sender: AnyObject) { if UIImagePickerController.isCameraDeviceAvailable( UIImagePickerControllerCameraDevice.Front) { imagePicker.delegate = self imagePicker.sourceType = UIImagePickerControllerSourceType.Camera presentViewController(imagePicker, animated: true, completion: nil) } } 

我知道，相机的作品，但如何使其工作，而不必按下button？

Answer 1

这是你的解决scheme。

把你的代码放在viewDidAppear方法中：

 override func viewDidAppear(animated: Bool) { if UIImagePickerController.isCameraDeviceAvailable( UIImagePickerControllerCameraDevice.Front) { imagePicker.delegate = self imagePicker.sourceType = UIImagePickerControllerSourceType.Camera presentViewController(imagePicker, animated: true, completion: nil) } } 

这将在您的应用程序启动时加载相机。

尝试在viewDidLoad中执行此操作将不起作用，因为在第一次创build视图之后调用该视图，并且此视图不是此时其他任何内容的子视图。

Answer 2

 override func viewDidLoad() { if UIImagePickerController.isCameraDeviceAvailable( UIImagePickerControllerCameraDevice.Front) { imagePicker.delegate = self imagePicker.sourceType = UIImagePickerControllerSourceType.Camera presentViewController(imagePicker, animated: true, completion: nil) } }