将数据从CollectionView委托传递到另一个ViewController

Question

我是Swift的初学者。

我的UIViewController有CollectionView ，当用户单击CollectionViewCell到另一个ViewController时，我需要传递数据。 我尝试覆盖prepareForSegue但我注意到它先调用，然后在didSelectItemAtIndexPath上进行编码。

我的第一个ViewController代码：

import UIKit

class ViewController: UIViewController {

    ...

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

extension ViewController : UICollectionViewDataSource,UICollectionViewDelegate{

    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
        return 1
    }

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

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("collCell", forIndexPath: indexPath) as! MainCollectionViewCell

        ...
        return cell
    }

    func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {

        itemId = items[indexPath.item].id

        let distinationViewController = DistinationViewController()
        distinationViewController.itemId = itemId
    }   
}

我的Distination视图控制器代码

import UIKit

class DistinationViewController: UIViewController{

    var itemId : String!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        print(itemId)
    }
}

DistinationViewController中itemId的DistinationViewController nil

谢谢

Answer 1

您可以尝试通过以下代码更改视图：

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
        itemId = items[indexPath.item].id
        let distinationViewController = self.storyboard.instantiateViewControllerWithIdentifier("DestinationViewControllerStoryBoardID") as! DistinationViewController

        distinationViewController.itemId = itemId
self.navigationController.pushViewController(distinationViewController, animated: true)
}

Answer 2

您需要做两件事：

1. 将您的func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath)更改为以下内容：

     func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) { // Here you can check which Collection View is triggering the segue if collectionView == collectionView1 { self.performSegueWithIdentifier("fromFirstCollectionView", sender: nil); } else if collectionView == collectionView2 { // from other CollectionView } } 

   您的prepareForSegue方法将如下所示

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { // Even here you can check for segue.identifiers if you have something to differentiate let dvc = segue.destinationViewController as! DestinationViewController dvc.itemId = "Hello" } 

2. 从View Controller连接segue并为其分配identifier

根据您的评论，您有3个collectionView所以我想您需要3个带有3个不同标识符的segue。

希望这可以帮助！ 如果您还有其他问题，很高兴与您讨论。

Answer 3

您可以将所有内容都放入prepareForSegue中。 像这样：

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if let identifier = segue.identifier{
        switch identifier {
            case "distinationViewController":
                if let nextScene =  segue.destinationViewController as? DistinationViewController {
                    if let indexPath = self.collectionView.indexPathsForSelectedItems.lastItem {
                        nextScene.itemId=items[indexPath.item].id
                        nextScene.delegate = self
                }
            }
            default: break
        }
    }
}