关闭相机并返回应用程序需要很长时间

Question

我有一个应用程序可以让用户添加他的图像。为此，我使用 UIImagePicker。

请看下面的函数： 当点击图像时，它会以弹出窗口的形式打开一个视图。

func imageTapped(tapGestureRecognizer: UITapGestureRecognizer)
{


    let userDetails:Dictionary = (UserDefaults.standard.value(forKey: "myUserDetails") as? [String:Any])!
    let UserID:Int = userDetails["UserID"] as! Int

    let popOverVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "imager") as! imagerVC
    popOverVC.UserID = UserID

    self.addChildViewController(popOverVC)
    popOverVC.view.frame = self.view.frame
    self.view.addSubview(popOverVC.view)

    popOverVC.didMove(toParentViewController: self)


    popOverVC.callback = { image in
        // do something with the image


        self.profile_image.image = image
        if let data = UIImagePNGRepresentation(image) {
            //save profile image as NewUserID
            UserDefaults.standard.set(data, forKey: String(UserID))
            UserDefaults.standard.synchronize()
        }
    }  
}

这是激活相机的视图代码，该视图在上面的代码中以 popOverVC 的形式打开。

    import UIKit

    class imagerVC: UIViewController,  UIImagePickerControllerDelegate, UINavigationControllerDelegate {
        var UserID:Int = 0
        @IBOutlet weak var myImageView: UIImageView!
        var callback : ((UIImage) -> ())?

        @IBOutlet weak var btn_end: UIButton!
        @IBOutlet weak var from_camera: UIBarButtonItem!
        @IBOutlet weak var from_gallery: UIBarButtonItem!

        @IBAction func btn_end_pressed(_ sender: UIButton) {
             self.view.removeFromSuperview()
        }

        @IBAction func btn_closer(_ sender: UIButton) {
             self.view.removeFromSuperview()
        }


        @IBAction func photofromLibrary(_ sender: UIBarButtonItem) {
            picker.allowsEditing = false
            picker.sourceType = .photoLibrary
            picker.mediaTypes = UIImagePickerController.availableMediaTypes(for: .photoLibrary)!
            picker.modalPresentationStyle = .popover
            present(picker, animated: true, completion: nil)
            picker.popoverPresentationController?.barButtonItem = sender
        }



        @IBAction func shootPhoto(_ sender: UIBarButtonItem) {
            if UIImagePickerController.isSourceTypeAvailable(.camera) {

                UserDefaults.standard.set(true, forKey: "is_selfie")
                UserDefaults.standard.synchronize()

                DispatchQueue.main.async {
                    self.picker.allowsEditing = false
                    self.picker.sourceType = UIImagePickerControllerSourceType.camera
                    self.picker.cameraCaptureMode = .photo
                    self.picker.modalPresentationStyle = .fullScreen
                    self.present(self.picker,animated: true,completion: nil)
                }

            } else {
                noCamera()
            }    
        }


        let picker = UIImagePickerController()

        override func viewDidLoad() {
            super.viewDidLoad()
            picker.delegate = self   
        }

        override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
            // Dispose of any resources that can be recreated.
        }


        //MARK: - Delegates
        func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject])
        {
            let chosenImage = info[UIImagePickerControllerOriginalImage] as! UIImage
            myImageView.contentMode = .scaleAspectFit //3
            myImageView.image = chosenImage //4


            myImageView.layer.borderWidth = 1
            myImageView.layer.masksToBounds = false
            myImageView.layer.borderColor = UIColor.black.cgColor
            myImageView.layer.cornerRadius = myImageView.frame.height/4
            myImageView.clipsToBounds = true

            callback?(chosenImage)

            dismiss(animated:true, completion: nil)  
        }

        func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
            dismiss(animated: true, completion: nil)
        }

        func noCamera(){
            let alertVC = UIAlertController(
                title: "No Camera",
                message: "Sorry, this device has no camera",
                preferredStyle: .alert)
            let okAction = UIAlertAction(
                title: "OK",
                style:.default,
                handler: nil)
            alertVC.addAction(okAction)
            present(
                alertVC,
                animated: true,
                completion: nil)
        }       
}

我有两个问题。也许他们是相关的。 主要问题是在相机视图加载并拍摄照片后，当我按下按钮使用照片时，相机不会立即关闭，并且在相机视图被关闭之前大约有一分钟的延迟。顺便说一下，一旦按下“使用照片”按钮，就会触发回调函数。

我不确定这是否已连接，但我收到以下警告： 实例方法 'imagePickerController(_:didFinishPickingMediaWithInfo:)' 几乎符合要求，但当我让 Xcode 自动更正我时，相机功能停止运行。

我试着换行 解雇（动画：真，完成：无） 在 DispatchQueue.main.async 中使其在主线程上运行，但这不起作用

不知道为什么，但物理 iPad 没有延迟，只有 iPhone 设备

非常感谢您提供的任何帮助

Answer 1

这是模拟器上的预期行为。它不应该在设备上滞后，正如你所说的它在设备上工作然后它很酷。 ！！！