我是 swift 的新手。我用了LTBA components构建快速应用程序。我按照一些教程来开发像推特这样的社交应用程序。我开始实现跟随按钮功能。它调用另一个 API 调用，但相同的响应带有较小的修改(例如 - 追随者属性的数量增加一个)。通话也能正常工作。但 Collection View 没有重新加载。我的代码是。

View Controller

import LBTAComponents
import TRON
import SwiftyJSON

class HomeDatasourceController: DatasourceController {
    let errorMessageLabel: UILabel = {
        let label = UILabel()
        label.text = "Apologies something went wrong. Please try again later..."
        label.textAlignment = .center
        label.numberOfLines = 0
        label.isHidden = true
        return label
    }()

    override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {
        collectionViewLayout.invalidateLayout()
    }

    func follow(){
        print("inside controller")
        Service.sharedInstance.fetchfollowHomeFeed { (homeDatasource, err) in
            if let err = err {
                self.errorMessageLabel.isHidden = false
                if let apiError = err as? APIError<Service.JSONError> {
                    if apiError.response?.statusCode != 200 {
                    self.errorMessageLabel.text = "Status code was not 200"
                    }
                }
                return
            }
            self.datasource = homeDatasource
            self.collectionView?.reloadData()
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(errorMessageLabel)
        errorMessageLabel.fillSuperview() //LBTA method call

        collectionView?.backgroundColor = UIColor(r: 232, g: 236, b: 241)

        setupNavigationBarItems()

        Service.sharedInstance.fetchHomeFeed { (homeDatasource, err) in
            if let err = err {
                self.errorMessageLabel.isHidden = false

                if let apiError = err as? APIError<Service.JSONError> {

                    if apiError.response?.statusCode != 200 {
                        self.errorMessageLabel.text = "Status code was not 200"
                    }
                }

                return
            }

            self.datasource = homeDatasource
        }
    }

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

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

        //first section of users
        if indexPath.section == 0 {
            guard let user = self.datasource?.item(indexPath) as? User else { return .zero }

            let estimatedHeight = estimatedHeightForText(user.bioText)
            return CGSize(width: view.frame.width, height: estimatedHeight + 66)
        } else if indexPath.section == 1 {
            //our tweets size estimation

            guard let tweet = datasource?.item(indexPath) as? Tweet else { return .zero }

            let estimatedHeight = estimatedHeightForText(tweet.message)

            return CGSize(width: view.frame.width, height: estimatedHeight + 74)
        }


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

    private func estimatedHeightForText(_ text: String) -> CGFloat {
        let approximateWidthOfBioTextView = view.frame.width - 12 - 50 - 12 - 2
        let size = CGSize(width: approximateWidthOfBioTextView, height: 1000)
        let attributes = [NSFontAttributeName: UIFont.systemFont(ofSize: 15)]

        let estimatedFrame = NSString(string: text).boundingRect(with: size, options: .usesLineFragmentOrigin, attributes: attributes, context: nil)

        return estimatedFrame.height
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        if section == 1 {
            return .zero
        }
        return CGSize(width: view.frame.width, height: 50)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
        if section == 1 {
            return .zero
        }
        return CGSize(width: view.frame.width, height: 64)
    }
}

数据单元格

import LBTAComponents

class UserCell: DatasourceCell {

    override var datasourceItem: Any? {
        didSet {
            guard let user = datasourceItem as? User else { return }
            followButton.addTarget(self, action: #selector(follow), for: .touchUpInside)
            nameLabel.text = user.name
            usernameLabel.text = user.username
            bioTextView.text = user.bioText

            profileImageView.loadImage(urlString: user.profileImageUrl)
        }
    }

    let profileImageView: CachedImageView = {
        let imageView = CachedImageView()
        imageView.image = #imageLiteral(resourceName: "profile_image")
        imageView.layer.cornerRadius = 5
        imageView.clipsToBounds = true
        return imageView
    }()

    let nameLabel: UILabel = {
        let label = UILabel()
        label.text = "Brian Voong"
        label.font = UIFont.boldSystemFont(ofSize: 16)
        return label
    }()

    let usernameLabel: UILabel = {
        let label = UILabel()
        label.text = "@buildthatapp"
        label.font = UIFont.systemFont(ofSize: 14)
        label.textColor = UIColor(r: 130, g: 130, b: 130)
        return label
    }()

    let bioTextView: UITextView = {
        let textView = UITextView()
        textView.text = "iPhone, iPad, iOS Programming Community. Join us to learn Swift, Objective-C and build iOS apps!"
        textView.font = UIFont.systemFont(ofSize: 15)
        textView.backgroundColor = .clear
        return textView
    }()

    let followButton: UIButton = {
        let button = UIButton()
        button.layer.cornerRadius = 5
        button.layer.borderColor = twitterBlue.cgColor
        button.layer.borderWidth = 1
        button.setTitle("Follow", for: .normal)
        button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 14)
        button.setTitleColor(twitterBlue, for: .normal)
        button.setImage(#imageLiteral(resourceName: "follow"), for: .normal)
        button.imageView?.contentMode = .scaleAspectFit
        button.imageEdgeInsets = UIEdgeInsets(top: 0, left: -8, bottom: 0, right: 0)
        //        button.titleEdgeInsets = UIEdgeInsets
        return button
    }()
    func follow(){
        print("inside source")
        var link = HomeDatasourceController()
        link.follow()
    }
    override func setupViews() {
        super.setupViews()

        backgroundColor = .white

        separatorLineView.isHidden = false
        separatorLineView.backgroundColor = UIColor(r: 230, g: 230, b: 230)

        addSubview(profileImageView)
        addSubview(nameLabel)
        addSubview(usernameLabel)
        addSubview(bioTextView)
        addSubview(followButton)

        profileImageView.anchor(self.topAnchor, left: self.leftAnchor, bottom: nil, right: nil, topConstant: 12, leftConstant: 12, bottomConstant: 0, rightConstant: 0, widthConstant: 50, heightConstant: 50)

        nameLabel.anchor(profileImageView.topAnchor, left: profileImageView.rightAnchor, bottom: nil, right: followButton.leftAnchor, topConstant: 0, leftConstant: 8, bottomConstant: 0, rightConstant: 12, widthConstant: 0, heightConstant: 20)

        usernameLabel.anchor(nameLabel.bottomAnchor, left: nameLabel.leftAnchor, bottom: nil, right: nameLabel.rightAnchor, topConstant: 0, leftConstant: 0, bottomConstant: 0, rightConstant: 0, widthConstant: 0, heightConstant: 20)

        bioTextView.anchor(usernameLabel.bottomAnchor, left: usernameLabel.leftAnchor, bottom: self.bottomAnchor, right: self.rightAnchor, topConstant: -4, leftConstant: -4, bottomConstant: 0, rightConstant: 0, widthConstant: 0, heightConstant: 0)

        followButton.anchor(topAnchor, left: nil, bottom: nil, right: self.rightAnchor, topConstant: 12, leftConstant: 0, bottomConstant: 0, rightConstant: 12, widthConstant: 120, heightConstant: 34)
    }
}

它使用 LBTA 组件。我尝试了 self.collectionView?.reloadData() 但它没有重新加载。请帮我解决这个问题。请帮我解决这个问题

最佳答案

请注意，您在 follow() 方法中使用了闭包，因此您需要在主队列中编写用于重新加载的代码。

像这样写下你的重载代码

DispatchQueue.main.async{
   self.collectionView.reloadData()
}

关于ios - 单击按钮的 Swift 重新加载 Collection View 不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49123836/