Swift 4-從UICollectionView單元中推送ViewController

Question

我被困在我的項目中，需要一些幫助。 我想從包括我的UINavigationBar的UICollectionViewCell推送/呈現一個UICollectionViewController 。 我了解您實際上不能從Cell呈現ViewController嗎？ 在這種情況下我該怎么辦？ 我的問題是我的NavigationBar無法顯示。

這是我的手機：

import UIKit
import Firebase

class UserProfileHeader: UICollectionViewCell, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

lazy var followersLabelButton: UIButton = {
    let button = UIButton(type: .system)
    button.setTitle("followers", for: .normal)
    button.setTitleColor(UIColor.lightGray, for: .normal)
    button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 14)
    button.addTarget(self, action: #selector(followers), for: .touchUpInside)
    return button
}()

@objc fileprivate func followers() {

    let newController = NewController(collectionViewLayout: UICollectionViewFlowLayout())

    self.window?.rootViewController?.present(newController, animated: true, completion: nil)


    }

   }

還有CollectionViewController：

import UIKit
import MapKit
import Firebase

class UserProfileController: UICollectionViewController, UICollectionViewDelegateFlowLayout, UIGestureRecognizerDelegate {

    var userId: String?

    override func viewDidLoad() {
        super.viewDidLoad()

        collectionView?.backgroundColor = UIColor.white


        collectionView?.register(UserProfileHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "headerId")

    }


    override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as! UserProfileHeader

        header.user = self.user

        return header
    }


    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {


        return CGSize(width: view.frame.width, height: 200)


    }


}

Answer 1

1-細胞內部

weak var delegate:UserProfileController?

2-內部cellForItemAt

cell.delegate = self

3-在細胞內使用

delegate?.present(newController, animated: true, completion: nil)

順便說一句，我認為你的意思是

delegate?.navigationController?.pushViewController(newController, animated: true)  

Answer 2

如果要呈現新的ViewController，則應在Cell中創建一個新的委托，如下所示：

import UIKit
import Firebase

protocol CellDelegate {
    func presentViewController()
}    

class UserProfileHeader: UICollectionViewCell, 
UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    var delegate: CellDelegate?

    lazy var followersLabelButton: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("followers", for: .normal)
        button.setTitleColor(UIColor.lightGray, for: .normal)
        button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 14)
        button.addTarget(self, action: #selector(followers), for: .touchUpInside)
        return button
    }()

    @objc func followers() {
        delegate.presentViewController
    }

}

在ViewController中時，應使委托函數像這樣工作

import UIKit
import MapKit
import Firebase

class UserProfileController: UICollectionViewController, UICollectionViewDelegateFlowLayout, UIGestureRecognizerDelegate
 , CellDelegate {

    var userId: String?

    override func viewDidLoad() {
        super.viewDidLoad()
        collectionView?.backgroundColor = UIColor.white
        collectionView?.register(UserProfileHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "headerId")
    }


    override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as! UserProfileHeader

        header.user = self.user

        // Remember to set the delegate for the cell
        header.delegate = self

        return header
    }


    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        return CGSize(width: view.frame.width, height: 200)
    }

    func presentViewController() {
        let newController = NewController(collectionViewLayout: UICollectionViewFlowLayout())

        self.window?.rootViewController?.present(newController, animated: true, completion: nil)
    }

}

Answer 3

考慮到這樣做是不正確的。 使用MVC方式：移動

button.addTarget(self, action: #selector(followers), for: .touchUpInside)

方法中的UserProfileController

override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as! UserProfileHeader as! UserProfileHeader
        header.followersLabelButton.addTarget(self, action: #selector(followers), for: .touchUpInside)
        header.user = self.user

        return header
    }

並重寫

@objc func followers() {

    let newController = self.navigationController

    newController?.present(newController, animated: true, completion: nil)


}

Answer 4

我真的認為您根本不應該從單元格中進行演示，即使您引用了viewController。 我寧願在委托上調用一個函數，然后讓它決定要做什么-

import UIKit
import Firebase

protocol UserProfileHeaderDelegate: class {
    func followersTapped()
}


class UserProfileHeader: UICollectionViewCell, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

    weak var headerDelegate: UserProfileHeaderDelegate?

    lazy var followersLabelButton: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("followers", for: .normal)
        button.setTitleColor(UIColor.lightGray, for: .normal)
        button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 14)
        button.addTarget(self, action: #selector(followers), for: .touchUpInside)
        return button
    }()

    @objc fileprivate func followers() {
        self.headerDelegate?.followersTapped()
    }
}

在viewController中-

class UserProfileController: UICollectionViewController, UICollectionViewDelegateFlowLayout, UserProfileHeaderDelegate {

    // etc, etc......

    override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {

        let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as! UserProfileHeader

        header.user = self.user

        // Remember to set the delegate for the cell
        header.headerDelegate = self

        return header
    }


    // Implement the UserProfileHeaderDelegate protocol - this is called from within the cell
    // so all the cell knows is that its delegate implements this protocol, which has the followersTapped() function

    func followersTapped() {
        let newController = NewController(collectionViewLayout: UICollectionViewFlowLayout())
        self.present(newController, animated: true, completion: nil)
    }
}

這樣，您的viewController無需擔心單元的內部工作原理，反之亦然。