IBOutlet nil after instantiateViewControllerWithId

问题:

Not sure exactly what I'm doing wrong here. I've listed out what my problem is and my code. Would love to get some help.

Thanks!

Problem:

• VC1 presents VC2.
• IBOutlets from VC1 are now nil.
• VC2 dismisses back into VC1.
• IBOutlets in VC1 are still nil.

VC1 loads a grid of pictures from flickR. VC2 has a searchBar controller, when VC2 is dismissed it does runs flickR query. Right before my self.collectionView.reload() fails because self.collectionView is nil :(

VC1

import UIKit

class MainViewController: UIViewController, UICollectionViewDelegate,    UICollectionViewDataSource {

@IBOutlet var collectionView: UICollectionView!
@IBOutlet var searchMask: UIView!

let api_key = "f87357398a52b80e0c9f76bf94c8ee94"

var flickResults:NSMutableArray! = NSMutableArray()
var titleResults:NSMutableArray! = NSMutableArray()

override func viewDidLoad() {
    super.viewDidLoad()
     loadPhotos("Brasil")
    // Do any additional setup after loading the view.
}

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
}

func loadPhotos(searchString: String) {
    let flickr:FlickrHelper = FlickrHelper()
    println("Collection: \(self.collectionView)")
    flickr.request(searchString, per_page: 50, completion: { (searchStr, flickrPhotos, photoTitle) -> () in
        dispatch_async(dispatch_get_main_queue(), {
            self.flickResults = flickrPhotos
            self.titleResults = photoTitle
            self.collectionView.reloadData()
        })
    })
}

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

override func preferredStatusBarStyle() -> UIStatusBarStyle {
    return UIStatusBarStyle.LightContent
}


func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    let cell: PhotoCell = self.collectionView.dequeueReusableCellWithReuseIdentifier("photoCell", forIndexPath: indexPath) as PhotoCell
    cell.photoImageView.alpha = 0
    let queue:dispatch_queue_t = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)

    dispatch_async(queue, {
        let searchURL: String = self.flickResults.objectAtIndex(indexPath.item) as String
        let title: String = self.titleResults.objectAtIndex(indexPath.item) as String
        let image: UIImage = self.loadImage(searchURL)
        dispatch_async(dispatch_get_main_queue(), {
            UIView.animateWithDuration(0.5, animations: {
                cell.photoImageView.image = image
                cell.photoTitle.text = title.capitalizedString
                cell.photoImageView.alpha = 1
            })

        })
    })

    insertBlurView(cell.titleMask, UIBlurEffectStyle.Dark)

    return cell
}

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return self.flickResults.count
}

func loadImage(imageUrl: String) -> UIImage{
    let url = NSURL(string: imageUrl)
    let data = NSData(contentsOfURL: url!)
    let image = UIImage(data: data!)
    return image!
}


@IBAction func searchButtonPressed(sender: UIButton) {
    let storyboard = UIStoryboard(name: "Main", bundle: nil);
    let vc: SearchViewController = storyboard.instantiateViewControllerWithIdentifier("Search") as SearchViewController
    providesPresentationContextTransitionStyle = true
    definesPresentationContext = true
    vc.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext
    self.presentViewController(vc, animated: false, completion: nil)

}
}

VC2

 import UIKit


 class SearchViewController: UIViewController, UITextFieldDelegate, UISearchBarDelegate, UICollectionViewDelegate {


@IBOutlet var searchMask: UIView!
@IBOutlet var searchField: UITextField!
@IBOutlet var searchBar: UISearchBar!

override func viewDidLoad() {
    super.viewDidLoad()
    insertBlurView(self.searchMask, UIBlurEffectStyle.Dark)
}

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

@IBAction func exitTap(sender: UIButton) {
    self.dismissViewControllerAnimated(true, completion: nil)
}


func searchBarSearchButtonClicked(searchBar: UISearchBar) {
    self.dismissViewControllerAnimated(true, completion: {
        let mainvc = self.storyboard?.instantiateViewControllerWithIdentifier("Main") as MainViewController
        mainvc.loadPhotos(searchBar.text)
    })
  }
}

回答1:

Thanks to rdelmar, I was able to figure this out using protocols.

Here's what I added:

• SearchDelegate
• SearchDelegate function runSearch()

VC1

class MainViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, SearchDelegate {  

func runSearch(searchString: String) {
    loadPhotos(searchString)
 }

}

VC2

protocol SearchDelegate {
    func runSearch(searchString: String)
 }

class SearchViewController: UIViewController, UITextFieldDelegate, UISearchBarDelegate, UICollectionViewDelegate {


@IBOutlet var searchMask: UIView!
@IBOutlet var searchField: UITextField!
@IBOutlet var searchBar: UISearchBar!

var delegate: SearchDelegate?

func searchBarSearchButtonClicked(searchBar: UISearchBar) {
    delegate?.runSearch(searchBar.text)
    self.dismissViewControllerAnimated(true, completion:nil)

}