有没有办法控制在完成图像选择器后哪个视图控制器被缝合

Question

在我正在处理的应用程序中，我有一个图像选择器，通过点击视图控制器1上的按钮来调用。选择图像后，我想将其发送到视图控制器2，以便用户可以在上载之前输入有关图像的元数据。

在下面的代码中我有这个工作正常，但有一件事我无法弄清楚。当我看到控制器2时，第一个视图控制器总是闪烁到屏幕上，而不是立即切换到查看控制器2.一系列事件似乎是图像选择器解散 - >视图控制器1短暂出现 - >准备segue进程 - >然后查看控制器2的负载。

有没有办法可以更改我的代码，以便在选择图像后立即查看控制器2的segue？如果由于图像选择器被取消而未选择图像，我想返回查看控制器1。

import UIKit
import Parse

class UserHome: UIViewController {

var newImage: UIImage?

@IBOutlet weak var welcomeLabel: UILabel!
@IBOutlet weak var imageArea: UIImageView!
@IBOutlet weak var currentUser: UIButton!
@IBAction func tapLogOut(_ sender: Any) {
    PFUser.logOut()
}
@IBAction func tapWeddingInfo(_ sender: Any) {
    opeURLFromString(urlString: weddingURL)
}
@IBAction func tapSlideShow(_ sender: Any) {
    self.performSegue(withIdentifier: "showSlideShow", sender: self)
}
@IBAction func tapAddImage(_ sender: Any) {
    print("tapped add image")
    let imagePicker = UIImagePickerController()
    imagePicker.delegate = self
    imagePicker.sourceType = .photoLibrary
    imagePicker.allowsEditing = false
    self.present(imagePicker, animated: true, completion: nil)
}
override func viewDidLoad() {
    super.viewDidLoad()
    loadPage()
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "showImageSubmit"{
        let vc = segue.destination as! ImageSubmit
        vc.newImage = newImage
    }
}
func loadPage() {
    print("query a database for images")
    print("load an array with those images")
    // Figure out a way to have images scroll into viewing area
    if let userEmail = PFUser.current()?.username {
        currentUser.setTitle(userEmail, for: [])
    }
    imageArea.image = UIImage(named: userHomeImage)
    welcomeLabel.text = userHomeMsg

    print ("loaded User Home")
    }
}
extension UserHome: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    public func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

        if let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage {
            // Convert image into PFFile data type
            // self.imageArea.image = image
            newImage = image
            self.dismiss(animated: true, completion: nil)
        }
        self.performSegue(withIdentifier: "showImageSubmit", sender: self)
    }

}

Answer 1

你可以使用completion的dismiss方法。在UIImagePickerController被解雇后，然后出现下一个控制器

public func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

    guard let image = info[.originalImage] as? UIImage else { 
        // dismiss(animated: true)
        return
    }
    // Convert image into PFFile data type
    // self.imageArea.image = image
    newImage = image

    dismiss(animated: true) {
        self.performSegue(withIdentifier: "showImageSubmit", sender: self)
    }
}