Question

我需要在导航回特定视图时重新加载集合视图。

我尝试实施以下所有内容但不起作用

1.在viewDidAppear（）中调用self.collectionView.reloadData（）

2.在viewWillAppear（）中调用self.collectionView.reloadData（）

即使我尝试在viewDidAppear中调用viewDidLoad（），但它仍无效。

并检查了其他相同类型的问题，但它不起作用...... 它唯一有效的方法是通过执行segue动作，但我不这么认为这样有效可以有人建议我任何想法吗？

enter code here class RoomDeviceListVC: UIViewController , UICollectionViewDelegate , UICollectionViewDataSource , UICollectionViewDelegateFlowLayout ,segueAction{

let functions = DataFunctionalities()
@IBOutlet weak var collectionView1: UICollectionView!
@IBOutlet weak var collectionView2: UICollectionView!
var horizontalBarLeadingConstraint : NSLayoutConstraint?
static var isVisible : Bool?
static var CollectionViewSection : Int!

static var reloadFlag : Int!

static var delegates : CollectionViewRotation? = nil

var uiFunctions  = UIFunctions()
var selectedIndex =  IndexPath(item: 0, section: 0)
var constant : CGFloat?
let headerView = UIView()

override func viewDidLoad() {
    super.viewDidLoad()
    uiFunctions.setViewBackground(view: self.view)
    self.navigationItem.hidesBackButton = true

    setupHeader()
    setupConstraints()
    setupHorizontalBar()
    collectionView2.clipsToBounds = true
    RoomDeviceListVC.CollectionViewSection = selectedIndex.section
    BottomViewRoomCell.delegates = self


}
override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)
   //  self.collectionView2.reloadData() 

}

override func viewDidAppear(_ animated: Bool) {
    super.viewWillAppear(true)
    self.collectionView2.reloadData()
    RoomDeviceListVC.isVisible = true

}

override func viewDidDisappear(_ animated: Bool) {
       RoomDeviceListVC.isVisible = false
}

func setupHorizontalBar(){
    let horizontalBar = UIView()
    self.view.addSubview(horizontalBar)
    horizontalBar.translatesAutoresizingMaskIntoConstraints = false
    horizontalBar.backgroundColor = .white
    horizontalBarLeadingConstraint = horizontalBar.leadingAnchor.constraint(equalTo: collectionView2.leadingAnchor)
    horizontalBarLeadingConstraint?.isActive = true
    horizontalBar.heightAnchor.constraint(equalToConstant: 3).isActive = true
    NSLayoutConstraint(item: horizontalBar, attribute: .width, relatedBy: .equal, toItem: collectionView1, attribute: .width, multiplier: 0.5, constant: 1).isActive =  true
    horizontalBar.bottomAnchor.constraint(equalTo: collectionView2.topAnchor).isActive = true

}




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

func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 2
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 1
}


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let menuName = ["Rooms" , "DeviceList"]
    let color :[UIColor] = [.green , .blue]


    if collectionView == collectionView1{
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "MenuBarCell", for: indexPath) as! MenuBarCell
        cell.menuLabel.text = menuName[indexPath.section]
        cell.menuLabel.textColor = UIColor.darkGray

        DispatchQueue.main.async {
            self.collectionView1.selectItem(at: self.selectedIndex, animated: false, scrollPosition: .centeredHorizontally)
        }
        return cell

    }
    else {
        if indexPath.section == 0{
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "BottomViewRoomCell", for: indexPath) as! BottomViewRoomCell
            cell.backgroundColor  = .clear
            cell.layer.cornerRadius = 9
            cell.layer.masksToBounds = true
            return cell
        }
        else{
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "BottomViewDeviceCell", for: indexPath) as! BottomViewDeviceCell
            cell.backgroundColor  = .clear
            cell.layer.cornerRadius = 9
            cell.layer.masksToBounds = true
            return cell
        }
    }

}


public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize{

    if collectionView  == collectionView1{
        return CGSize(width: self.view.frame.width / 2, height: collectionView1.frame.height)
    }
    else{
        return CGSize(width: self.view.frame.width, height: collectionView2.frame.height)
    }

}

Answer 1

您可以使用UINavigationControllerDelegate来处理这种情况。

添加UINavigationControllerDelegate，将self签名到collectionView的navigationController的委托，然后将你的个人功能放在＆＃34; willShow / didShow＆＃34;委托方法。当您弹回collectionView时，将调用您的个人功能。

关于单元格显示的一些方法未显示

class HomeCollectionViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout, UINavigationControllerDelegate{
    private let cellId = "cellId"

    override func viewDidLoad() {
        super.viewDidLoad() 

    //  sign navigationController's delegate to collectionViewController itself.
        navigationController?.delegate = self
    }

    // push view controller when cell is selected
    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let vc = CustomViewController()
        navigationController?.pushViewController(vc, animated: true)
    }

    //  call your personal function when this collection view controller shows back
    func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
        if viewController == self {
            print("will show self")
        }
    }

    func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
        if viewController == self {
            print("did show self")
        }
    }
}

导航回来时UICollection View没有重新加载？

1 个答案: