OStack程序员社区-中国程序员成长平台

标题: ios - 如何在不重新加载标题的情况下重新加载 UICollectionView 中的单元格？ [打印本页]

---

作者: 菜鸟教程小白    时间: 2022-12-11 20:22
标题: ios - 如何在不重新加载标题的情况下重新加载 UICollectionView 中的单元格？

我正在尝试根据用户在标题中的 textField 中输入的内容来更新 UICollectionView 中单元格的内容。我在这里查看了其他类似的问题，但他们的答案似乎都不起作用。我什至尝试实现 UICollectionView 的扩展，该扩展通过该部分中的每个单元格尝试重新加载其数据，但这会导致崩溃的数量用户进入 textField 后，单元格会发生变化

我试图解决问题的功能，我只有一个部分，所以我在该部分中进行了硬编码

    @objc func textFieldDidChange(){
        guard(!(feedSearchBar.text?.isEmpty)!) else{
            VC.currentTagsArray = VC.genericTagsArray
            VC.feedScreenCollectionView.reloadData()
            return
        }
        VC.currentTagsArray = VC.genericTagsArray.filter({letter -> Bool in
            if feedSearchBar.text!.count > letter.count{
                return false
            }
            let stringRange = letter.index(letter.startIndex, offsetBy: feedSearchBar.text!.count)
            let subword = letter[..<stringRange]
            return subword.lowercased().contains(feedSearchBar.text!.lowercased())

        })

        if VC.currentTagsArray.isEmpty{
            VC.currentTagsArray.insert(feedSearchBar.text!, at: 0)
        }
    VC.feedScreenCollectionView.reloadItems(inSection: 0)
   }

extension UICollectionView{
    func reloadItems(inSection section:Int = 0) {
        print("made it to reload")
        for i in 0..<self.numberOfItems(inSection: section){
        self.reloadItems(at: [IndexPath(item: i, section: section)])
        }
    }
}

这是项目的全部代码

import UIKit

class ViewController: UIViewController,UICollectionViewDelegateFlowLayout,UICollectionViewDelegate,UICollectionViewDataSource,printDelegateWorkedDelegate,updateCollectionView{

    func updateCollectionView() {
        self.feedScreenCollectionView.reloadData()
    }

    func printDelegateWorkedDelegate() {
        print("The delegate worked")
    }

    var genericTagsArray:[String] = ["tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za","tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za"]
    var currentTagsArray:[String] = [String]()
    var tagsSelected:[String] = [String]()
    let keyboardSlider = KeyboardSlider()

    var header:feedViewHeader = feedViewHeader()

    @IBOutlet weak var feedScreenCollectionView: UICollectionView!

    override func viewDidLoad() {
        super.viewDidLoad()
        keyboardSlider.subscribeToKeyboardNotifications(view: view)
        currentTagsArray = genericTagsArray

        let viewTapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(feedViewHeader.viewTapped(gestureRecognizer))
        viewTapGestureRecognizer.cancelsTouchesInView = false
        self.feedScreenCollectionView.addGestureRecognizer(viewTapGestureRecognizer)

        feedScreenCollectionView.delegate = self
        //
        feedScreenCollectionView.dataSource = self
        //

        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
        layout.sectionInset = UIEdgeInsets(top: 5, left: 1, bottom: 0, right: 1)
        layout.minimumLineSpacing = 0
        layout.headerReferenceSize = CGSize(width: 50, height: 75)

        layout.sectionHeadersPinToVisibleBounds = true
        feedScreenCollectionView.collectionViewLayout = layout
    }
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
            return CGSize(width: 50, height: 75)
    }
    func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
                header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "feedViewHeader", for: indexPath) as! feedViewHeader
            header.VC = self
        return header

    }
    //


    //Data Source
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return currentTagsArray.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "feedViewCell", for: indexPath) as! feedViewCell
        cell.feedImageView.backgroundColor = .blue
        cell.feedImageView.clipsToBounds = true
        cell.feedImageView.layer.cornerRadius = CGFloat((cell.feedImageView.frame.width)/5)
        cell.feedLabel.text = currentTagsArray[indexPath.item]
        return cell
    }
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat{
        return 0
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let collectionViewWidth = collectionView.bounds.width/4.0
        let collectionViewHeight = collectionViewWidth
        return CGSize(width: collectionViewWidth-4, height: collectionViewHeight+25)
    }
    var lastContentOffset:CGFloat = 0

    func scrollViewDidScroll(_ scrollView: UIScrollView) {

        if self.lastContentOffset > self.feedScreenCollectionView.contentOffset.y && self.feedScreenCollectionView.contentOffset.y > 0 && self.feedScreenCollectionView.contentOffset.y < self.feedScreenCollectionView.frame.maxY {
            self.lastContentOffset = scrollView.contentOffset.y
            header.isHidden = false
        }
        else if (self.lastContentOffset < self.feedScreenCollectionView.contentOffset.y) && (self.feedScreenCollectionView.contentOffset.y < self.feedScreenCollectionView.frame.maxY) && (self.feedScreenCollectionView.contentOffset.y > 0)  {
            print("you scrolled down,content offSet: \(scrollView.contentOffset.y)->\(self.feedScreenCollectionView.contentOffset.y)")
            header.isHidden = true
        }
        else{
            self.lastContentOffset = scrollView.contentOffset.y
            print("content offSet: \(scrollView.contentOffset.y)")
            print("Nothing happened")
            //  self.headerDelegate?.hideHeaderView(hide: true)
        }


    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardFrameChangeNotification(notification), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
    }

    var offsetY:CGFloat = 0

    @objc func keyboardFrameChangeNotification(notification: Notification) {
    }


}


class feedViewCell:UICollectionViewCell{

    @IBOutlet weak var feedImageView: UIImageView!
    @IBOutlet weak var feedLabel: UILabel!

    let keyboardSlider = KeyboardSlider()

    override func awakeFromNib() {
        super.awakeFromNib()
        feedLabel.translatesAutoresizingMaskIntoConstraints = false
        feedImageView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
        feedImageView.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
        feedImageView.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
        feedImageView.bottomAnchor.constraint(equalTo: self.feedLabel.topAnchor).isActive = true

        feedImageView.translatesAutoresizingMaskIntoConstraints = false
        feedLabel.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
        feedLabel.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
        feedLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
        feedLabel.topAnchor.constraint(equalTo: self.feedImageView.bottomAnchor).isActive = true
        feedLabel.textAlignment = .center

    }

}




class feedViewHeader:UICollectionReusableView,UITextFieldDelegate,UICollectionViewDelegate{

    @IBOutlet weak var feedSearchBar: UITextField!

    var delegateWorked:printDelegateWorkedDelegate?
    var updateCV:updateCollectionView?


    var VC:ViewController!
    var collectionView:UICollectionView?
    var stringToBeSet = "String to be set"

    override func awakeFromNib() {
        super.awakeFromNib()

        feedSearchBar.delegate = self
        feedSearchBar.autocorrectionType = .no
        feedSearchBar.keyboardType = .default
          feedSearchBar.addTarget(self, action: #selector(feedViewHeader.textFieldDidChange), for: .editingChanged)
        self.feedSearchBar.borderStyle = .roundedRect
        self.feedSearchBar.layer.borderColor = UIColor.black.cgColor
        self.feedSearchBar.layer.borderWidth = 4
        var searchBarHeight = self.feedSearchBar.bounds.height
        self.feedSearchBar.placeholder = "Tap To Search"
        self.feedSearchBar.returnKeyType = .search
        self.feedSearchBar.rightViewMode = .always
    }


    @objc func viewTapped(gestureRecognizer:UIGestureRecognizer){

        if  feedSearchBar.isFirstResponder{
            feedSearchBar.resignFirstResponder()
        }
    }

   func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
     VC.feedScreenCollectionView.reloadData()

    //VC.feedScreenCollectionView.reloadSections([0])
    return true
    }

    /// Helper to dismiss keyboard
    @objc func didStopEditing() {
    }

    func textFieldDidEndEditing(_ textField: UITextField) {
        UIView.setAnimationCurve(UIViewAnimationCurve.easeInOut)
        UIView.animate(withDuration: 0.2) {
            self.VC.view.frame.origin.y = 0
        }
    }
    @objc func textFieldDidChange(){
        guard(!(feedSearchBar.text?.isEmpty)!) else{
            VC.currentTagsArray = VC.genericTagsArray
            VC.feedScreenCollectionView.reloadData()
            return
        }

        VC.currentTagsArray = VC.genericTagsArray.filter({letter -> Bool in
           if feedSearchBar.text!.count > letter.count{
                return false
            }
            let stringRange = letter.index(letter.startIndex, offsetBy: feedSearchBar.text!.count)
            let subword = letter[..<stringRange]
            return subword.lowercased().contains(feedSearchBar.text!.lowercased())

        })

        if VC.currentTagsArray.isEmpty{
            VC.currentTagsArray.insert(feedSearchBar.text!, at: 0)
        }
    VC.feedScreenCollectionView.reloadItems(inSection: 0)
   }
}

extension Notification.Name{
    static let showKeyboard = Notification.Name("showKeyboard")
}
class KeyboardSlider: NSObject {
    // variables to hold and process information from the view using this class
    weak var view: UIView?

    @objc func keyboardWillShow(notification: NSNotification) {
        // method to move keyboard up
        // view?.frame.origin.y = 0 - getKeyboardHeight(notification as Notification)
        print("made it to keyboard will show")
    }

    func getKeyboardHeight(_ notification:Notification) -> CGFloat {
        // get exact height of keyboard on all devices and convert to float value to return for use
        let userInfo = notification.userInfo
        let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
        return keyboardSize.cgRectValue.height
    }

    func subscribeToKeyboardNotifications(view: UIView) {
        // assigning view to class' counterpart
        self.view = view
        // when UIKeyboardWillShow do keyboardWillShow function
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification), name: .UIKeyboardWillShow, object: nil)
    }

    func unsubscribeFromKeyboardNotifications() {
        NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
    }
}

class blankView:UICollectionReusableView{

}

extension UICollectionView{
    func reloadItems(inSection section:Int = 0) {
        print("made it to reload")
        for i in 0..<self.numberOfItems(inSection: section){
        self.reloadItems(at: [IndexPath(item: i, section: section)])
        }
    }
}

---

Best Answer-推荐答案

你可以调用方法

Objective-C

- (void)reloadItemsAtIndexPathsNSArray *)indexPaths

swift

func reloadItems(at indexPaths: [IndexPath])

您可以在其中传递要更新的 indexPaths 数组。 更多信息请访问 Apple Documentation

关于ios - 如何在不重新加载标题的情况下重新加载 UICollectionView 中的单元格？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51409171/

---

欢迎光临 OStack程序员社区-中国程序员成长平台 (https://ostack.cn/)

Powered by Discuz! X3.4