无法使用swift 3从其dataSource获取单元格

时间:2016-10-20 14:51:36

标签: swift uitableview

我将下面的UITableViewController附加为searchResultsController:

import UIKit
import MapKit

class LocationSearchTable : UITableViewController {
    var matchingItems:[MKMapItem] = []
    var mapView: MKMapView? = nil

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.dataSource = self
        tableView.delegate = self
    }
}

extension LocationSearchTable : UISearchResultsUpdating {
    func updateSearchResults(for searchController: UISearchController){
        guard let mapView = mapView,
            let searchBarText = searchController.searchBar.text else { return }
        let request = MKLocalSearchRequest()
        request.naturalLanguageQuery = searchBarText
        request.region = mapView.region
        let search = MKLocalSearch(request: request)
        search.start { response, _ in
            guard let response = response else {
                return
            }
            self.matchingItems = response.mapItems
            self.tableView.reloadData()
        }
    }

}

extension LocationSearchTable {
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        print(matchingItems.count)
        return matchingItems.count
    }

     func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell")!
        let selectedItem = matchingItems[indexPath.row].placemark
        cell.textLabel?.text = selectedItem.name
        cell.detailTextLabel?.text = ""
        return cell
    }
}

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一旦matchingItems.count不等于0,它就崩溃了,例如:

  

0 0 10 2016-10-20 15:43:53.914 ios-App [9137:977735] *断言   失败 - [UITableView _configureCellForDisplay:forIndexPath:],   /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3599.6/UITableView.m:8035   2016-10-20 15:43:53.927 ios-App [9137:977735] * 终止app到期   未被捕获的异常' NSInternalInconsistencyException',原因:   ' UITableView(; layer =; contentOffset:{0,   -64}; contentSize:{768,440}>)无法从其dataSource获取单元格

当我在cellForRowAtIndexPath中添加调试点时,它们永远不会到达,应用程序似乎在此之前崩溃了吗?

1 个答案:

答案 0 :(得分:6)

错误

  

无法从其dataSource获取单元格

发生

是因为cellForRowAtIndexPath的签名错误。在Swift 3中它是

(override) func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell

并使用便捷方法

let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for:indexPath)

总是返回一个有效的非可选单元格。

PS:您不需要设置数据源并委托给self因为UITableViewController隐式执行此操作