代表返回nil - 斯威夫特

Question

這段代碼很簡單：

import UIKit 
import CoreData 

class PhotoList: UIViewController, UITableViewDelegate, UITableViewDataSource, sendDetailsDelegate { 

    override func viewDidLoad() { 
     super.viewDidLoad() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
    } 


    @IBOutlet var tableView: UITableView! 
    var whoTookArray: [String] = [] 
    var imageArray: [UIImage] = [] 

    func sendDetails (name: String, photo: UIImage) { 
     whoTookArray.append(name) 
     imageArray.append(photo) 
     tableView!.reloadData() 
    } 

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
     return whoTookArray.count 
    } 

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { 
     var cell = UITableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: nil) 
     let row = indexPath.row 
     let whoTookName = whoTookArray[row] 
     let image = imageArray[row] 
     cell.textLabel?.text = whoTookName 
     cell.imageView!.image = image 
     return cell 

    } 

} 

和

import UIKit 
import CoreData 

protocol sendDetailsDelegate { 
    func sendDetails(name: String, photo: UIImage) 
} 

class Details: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate { 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     let tapGestureRecognizer: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "chooseImage:") 
     tapGestureRecognizer.numberOfTapsRequired = 1 
     imageSelected.addGestureRecognizer(tapGestureRecognizer) 
     imageSelected.userInteractionEnabled = true 
    } 

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


    @IBOutlet var whoTookTextField: UITextField! 
    @IBOutlet var imageSelected: UIImageView! 
    var delegate: sendDetailsDelegate? 

    //Pick the image by tapping, accessing the PhotoLibrary 
    func chooseImage(recognizer: UITapGestureRecognizer) { 
     let imagePicker: UIImagePickerController = UIImagePickerController() 
     imagePicker.delegate = self 
     imagePicker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary 
     self.presentViewController(imagePicker, animated: true, completion: nil) 
    } 

    //Put the selected image into the screen 
    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) { 

     let pickedImage: UIImage = (info as NSDictionary).objectForKey(UIImagePickerControllerOriginalImage) as! UIImage 
     let smallPicture = scaleImageWith(pickedImage, newSize: CGSizeMake(288,148)) 
     var sizeOfImageView: CGRect = imageSelected.frame 
     sizeOfImageView.size = smallPicture.size 
     imageSelected.frame = sizeOfImageView 
     imageSelected.image = smallPicture 
     picker.dismissViewControllerAnimated(true, completion: nil) 
    } 

    func imagePickerControllerDidCancel(picker: UIImagePickerController) { 
     picker.dismissViewControllerAnimated(true, completion: nil) 
    } 

    func scaleImageWith(image: UIImage, newSize: CGSize) -> UIImage { 
     UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0) 
     image.drawInRect(CGRectMake(0,0, newSize.width, newSize.height)) 
     let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext() 
     UIGraphicsEndImageContext() 
     return newImage 
    } 


    @IBAction func addButton(sender: AnyObject) { 

     if whoTookTextField == nil || imageSelected == nil { return } 
     if imageSelected == nil { return } 


     let whoTook = whoTookTextField.text 
     let image = imageSelected.image 

     println("\(delegate)") 

     delegate!.sendDetails(whoTook, photo: image!) 


     println("whoTook: \(whoTook) image: \(image)") 

     if let navigation = self.navigationController { 
      navigation.popViewControllerAnimated(true) 
     } 
    } 
} 

我委託一個文本和圖像的PhotoList視圖控制器，但它在委託行崩潰這裏：

delegate!.sendDetails(whoTook, photo: image!) 

打印行說它是nil。有誰知道爲什麼？謝謝！

編輯

解決了！

Answer 1

添加以下代碼：

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { 
     if (segue.identifier == "toPhotoList") { 
      let view = segue.destinationViewController as! Details 
      view.delegate = self 
     } 
    } 

，您的所有煩惱都沒了！ Tableview更新成功！

感謝您的幫助！