ios - 无法通过当前模态转换将图像传递给另一个 UIViewController

Question

我试图将图像传递到目标 UIView 的另一个 imageView，它连接到源 UIView，超过当前模态 segue。

我试图通过 segue 传递数据，并通过 Outlet 在源 UIView 中设置图像(即 NSData - 核心数据)，但我收到错误 image description 在控制台中-

"fatal error: unexpectedly found nil while unwrapping an Optional value"

  //Code of destination UIView
   import UIKit
   import CoreData
   class ReviewViewController: UIViewController {

   @IBOutlet var backgroundImageView:UIImageView!
   var subject:Semester!       

    override func viewDidLoad() {
    super.viewDidLoad()
    backgroundImageView?.image = UIImage(data: subject.image!)
    let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Dark)
    let blurEffectView = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame = view.bounds
    backgroundImageView.addSubview(blurEffectView)

   // Code of Source UIView
  import UIKit
  import CoreData

  class SubjectDetailViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
  @IBOutlet var facultyImageView:UIImageView!
  var subject:Semester!

  override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "destinationidentifier"
    {
            let destinationController = segue.destinationViewController as! ReviewViewController
            destinationController.backgroundImageView?.image = self.facultyImageView.image
     }
}

Answer 1

您的问题是 backgroundImageView 对象为 nil，因为 destinationController 当前不在 window 层次结构中。

所以像这样改变你的prepareForSegue

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "destinationidentifier"
    {
        let destinationController = segue.destinationViewController as! ReviewViewController
        destinationController.image = self.facultyImageView.image
    }
} 

现在在 ReviewViewController 中创建一个图像对象，如下所示，并在 viewDidLoad 中添加一行

var image: UIImage!

override func viewDidLoad() {
    super.viewDidLoad()
    self.backgroundImageView?.image = self.image
}

希望对你有帮助