使用JSON快速分页

Question

我对JSON数据的分页存在一些问题。我只能显示一个页面，但我需要在最后一个单元格时显示下一页。

我用willDisplay尝试过这种方式，但它没有用。我想我需要将数据保存在某个数组中，但我不知道该怎么做。我也有来自JSON的数据模型。请帮助我，分页让我疯狂:(

请不要在viewDidLoad中注意func getDate，这是另一个问题：D

  import UIKit

    class FilmsViewController: UIViewController {

        @IBOutlet weak var tableView: UITableView!

        var searchController: UISearchController!

        var films = Films()
        var page = 1

        override func viewDidLoad() {
            super.viewDidLoad()
            searchController = UISearchController(searchResultsController: nil)
            searchController.searchResultsUpdater = self
            searchController.dimsBackgroundDuringPresentation = false
            tableView.tableHeaderView = searchController.searchBar
            tableView.reloadData()
            getDate(title: "World", page: page)
        }

        private let endPoint = "http://www.omdbapi.com/"

        func getDate(title: String, page: Int) {

            var urlComponents = URLComponents(string: endPoint)

            let querySearchNameOfFilm = URLQueryItem(name: "s", value: title)
            let querytypeOfFilms = URLQueryItem(name: "type", value: "movie")
            let queryPages = URLQueryItem(name: "page", value: String(page))
            let queryApiKey = URLQueryItem(name: "apikey", value: "a6c7f954")

            urlComponents?.queryItems = [querySearchNameOfFilm,
                                         querytypeOfFilms,
                                         queryPages,
                                         queryApiKey]

            guard let url = urlComponents?.url else { return }

            let session = URLSession.shared

            session.dataTask(with: url) { (data, response, error) in
                guard let data = data else { return }

                do {
                    self.films = try JSONDecoder().decode(Films.self, from: data)
                    DispatchQueue.main.async {
                        self.tableView.reloadData()
                    }
                } catch {
                    print(error)
                }
                }.resume()
        }

        // MARK: - Cells

        func configureCell(cell: FilmsCell, for indexPath: IndexPath) {

            guard let search = self.films.search else { return }
            let films = search[indexPath.row]
            cell.titleFilmLabel.text = films.title
            if let imageUrl = URL(string: films.poster!) {
                DispatchQueue.global().async {
                    guard let data = try? Data(contentsOf: imageUrl) else { return }
                    let image = UIImage(data: data)
                    DispatchQueue.main.async {
                        cell.imageFilm.image = image
                    }
                }
            }
        }
    }

    extension FilmsViewController: UISearchResultsUpdating {
        func updateSearchResults(for searchController: UISearchController) {
            getDate(title: searchController.searchBar.text!, page: page)
        }
    }

    extension FilmsViewController: UITableViewDelegate {

    }

    extension FilmsViewController: UITableViewDataSource {
        func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
            guard let search = self.films.search else { return 20 }
            return search.count
        }

        func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
            let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! FilmsCell

            configureCell(cell: cell, for: indexPath)

            return cell
        }

        func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {

            if let search = self.films.search {
                if indexPath.row == search.count - 1 {
                    page += 1
                    getDate(title: searchController.searchBar.text!, page: page)
                }
            }
        }
    }

Answer 1

这个有用的方式我在我的所有项目中都这样做。当用户到达tableview的末尾时，我调用api来获取数据。

override func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let  height = scrollView.frame.size.height
    let contentYoffset = scrollView.contentOffset.y
    let distanceFromBottom = scrollView.contentSize.height - contentYoffset
    if distanceFromBottom < height { // when you reach the bottom
         page += 1
         getDate(title: searchController.searchBar.text!, page: page)
    }
}

Answer 2

其中一个好的有效方法是在tableview中使用scrollviewDelegate。只需在viewController中添加UIScrollViewDelegate即可

//For Pagination
var isDataLoading:Bool=false
var pageNo:Int=0
var limit:Int=20
var offset:Int=0 //pageNo*limit
var didEndReached:Bool=false

override func viewDidLoad(_){
    tableview.delegate=self //To enable scrollviewdelegate
}

ScrollView Delegate方法。

func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {

    print("scrollViewWillBeginDragging")
    isDataLoading = false
}



func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    print("scrollViewDidEndDecelerating")
}


//Pagination
func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {

    print("scrollViewDidEndDragging")
    if ((tableView.contentOffset.y + tableView.frame.size.height) >= tableView.contentSize.height)
    {
        if !isDataLoading{
            isDataLoading = true
            self.pageNo=self.pageNo+1
            self.limit=self.limit+10
            self.offset=self.limit * self.pageNo
            loadCallLogData(offset: self.offset, limit: self.limit)
        }
    }
}