ios - UITableView 调用 cellFor row 但不在 UI 中绘制

Question

我正在调用 API 来搜索“ friend ”/(UserProfile 类)并希望将其显示在 tableView 中。我还在本地 session 中搜索工作正常的地方。

但是切换到 friend 分段控件(见下文)后，输入用户名并按回车键， friend 模式下的 tableView 保持为空。但日志表明已找到它并且 cellForRowAt: 返回一些内容。当我第二次输入查询的一个字母时， friend 只会出现在我的 tableView 中(没有对 API 的查询，因为我没有按 Enter 键)。

认为它可能是异步的东西，但看起来不错，附上了日志。

//
//  FilterViewController.swift


import Foundation
import UIKit

class FilterViewController: UIViewController {
  enum SearchState: String {
    case place = "Search for a place"
    case friend = "Search for a friend"
  }
  var searchState: SearchState = .place
  var placesResult: Array<Place> = []
  var friendResult: Array<UserProfile> = []
  @IBOutlet weak var searchBar: UISearchBar!
  @IBOutlet weak var tableView: UITableView!

  override func viewDidLoad() {
    self.placesResult = Session.shared.places
    self.searchBar.isTranslucent = true
    self.searchBar.autocapitalizationType = .none
    // self.searchBar.searchBarStyle = .prominent
    self.searchBar.barTintColor = UIColor.clear
    self.searchBar.scopeButtonTitles = [SearchState.place.rawValue, SearchState.friend.rawValue]
  }

  override func viewDidAppear(_ animated: Bool) {
    self.searchBar.showsScopeBar = true
    self.searchBar.becomeFirstResponder()
    self.searchBar.tintColor = UIColor.white
  }
}

extension FilterViewController: UISearchBarDelegate {

  // The places part works fine
  func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
    if searchText == "" {
      self.friendResult = []
      self.placesResult = []
      return
    }
    guard self.searchState == .place else {
      return
    }
    self.placesResult = Session.places(matching: searchText)
    print("FilterView search query: \(searchText)")
    tableView.reloadData()
  }

  func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
    /// We use it only for friends because for places we search on text change
    guard self.searchState == .friend else {
      return
    }
    //// HERE IS THE PART WHERE I QUERY.
    let query = UserProfileQuery(forName: searchBar.text!)
    query.performQuery() { results, error in
      print("Search User results: \(results.count) users")
      DispatchQueue.main.async {
        self.friendResult.removeAll()
        print("reload")
        for result in results {
          print(">>> Results: \(result["name"].debugDescription)")
          let userProfile = UserProfile(fromRecord: result)
          self.friendResult.append(userProfile)
        }
        print("calling tableView reloadSections. \(self.friendResult.count) friends")
        // self.tableView.reloadSections([0], with: .left)
        //self.tableView.reloadSections([0], with: .left)
        self.tableView.reloadData()
        //// AFTER THIS THE TABLEVIEW CALLS THE DATA SOURCE. ALL GOOD SO FAR
      }
    }

  }



  func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
    searchBar.text = ""
  }

  func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
    self.dismiss(animated: true, completion: nil)
  }

  func searchBar(_ searchBar: UISearchBar, selectedScopeButtonIndexDidChange selectedScope: Int) {
    switch selectedScope {
    case 0:
      self.searchState = .place
      self.searchBar.placeholder = SearchState.place.rawValue
    case 1:
      self.searchState = .friend
      self.searchBar.placeholder = SearchState.friend.rawValue
    default:
      print("Error: searchbar in FilterViewController has unknown scope: \(selectedScope)")
    }
  }

}


extension FilterViewController: UITableViewDelegate {


  func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    print("willDisplay cell: \(cell.debugDescription)")
  }

}

extension FilterViewController: UITableViewDataSource {

  func numberOfSections(in tableView: UITableView) -> Int {
    return 1
  }

  func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    switch self.searchState {
    case .place:
      print("Place \(self.placesResult.count)")
      return self.placesResult.count
    case .friend:
      print("numberOfRowsInSection: \(self.friendResult.count) friends")
      return self.friendResult.count
    }
  }

  func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    print("cellForRowAt: for state \(self.searchState) \(self.friendResult.count)")
    switch self.searchState {
    case .place:
      let cell = self.tableView.dequeueReusableCell(withIdentifier: "placeCell")!
      cell.textLabel?.text = self.placesResult[indexPath.item].name
      print("return place cell")
      return cell
    case .friend:
      let cell = self.tableView.dequeueReusableCell(withIdentifier: "friendCell")!
      cell.textLabel?.text = self.friendResult[indexPath.item].name
      //cell.userProfile = self.friendResult[indexPath.item]
      //cell.title.text = cell.userProfile.name
      print("return cell: \(cell.debugDescription)")
      return cell
    }

  }
}

这是上面打印的日志:

numberOfRowsInSection: 0 friends
numberOfRowsInSection: 0 friends
numberOfRowsInSection: 0 friends
numberOfRowsInSection: 0 friends
numberOfRowsInSection: 0 friends
Search User results: 1 users
reload
>>> Results: Optional(johnappleseed)
calling tableView reloadSections. 1 friends
numberOfRowsInSection: 1 friends
cellForRowAt: for state friend 1
return cell: <UITableViewCell: 0x7fdd15f02400; frame = (0 0; 300 44); text = 'johnappleseed'; clipsToBounds = YES; layer = <CALayer: 0x604001e25160>>
willDisplay cell: <UITableViewCell: 0x7fdd15f02400; frame = (0 0; 300 44); text = 'johnappleseed'; clipsToBounds = YES; autoresize = W; tintColor = UIExtendedSRGBColorSpace 0 0 1 1; layer = <CALayer: 0x604001e25160>>
numberOfRowsInSection: 1 friends
cellForRowAt: for state friend 1
return cell: <UITableViewCell: 0x7fdd16651a00; frame = (0 0; 300 44); text = 'johnappleseed'; clipsToBounds = YES; layer = <CALayer: 0x60000182b4e0>>
willDisplay cell: <UITableViewCell: 0x7fdd16651a00; frame = (0 0; 300 44); text = 'johnappleseed'; clipsToBounds = YES; autoresize = W; tintColor = UIExtendedSRGBColorSpace 0 0 1 1; layer = <CALayer: 0x60000182b4e0>>
numberOfRowsInSection: 1 friends
cellForRowAt: for state friend 1
return cell: <UITableViewCell: 0x7fdd15802000; frame = (0 0; 300 44); text = 'johnappleseed'; clipsToBounds = YES; layer = <CALayer: 0x604001e2eec0>>
willDisplay cell: <UITableViewCell: 0x7fdd15802000; frame = (0 0; 300 44); text = 'johnappleseed'; clipsToBounds = YES; autoresize = W; tintColor = UIExtendedSRGBColorSpace 0 0 1 1; layer = <CALayer: 0x604001e2eec0>>

所以它肯定应该显示单元格，但显示的是:

然后，当我再次单击搜索栏并输入“J”时，它会显示单元格:

这里出了什么问题？

Answer 1

好的，我找到了。

所以我想其中一些与苹果为 iOS 11 支持 searchBar 所做的更改有关。用于UINavigationController .

我做错的是我分配了 searchBar成为tableViewHeader .

当 searchBar 时，这就中断了显示 scopeBar .

在这种情况下，如果 searchBar 则有效。是一个独立于 tableView 的东西，并与自动布局连接，所以 searchBar位于 tableView 之上.

在这种情况下，UIViewController该容器不是 UITableViewController

我在此线程中发布了更多详细信息:UISearchBarController iOS 11 issue - SearchBar and scope buttons overlap

所以布局在 IB 中应该是这样的:

在 IB 中看起来很奇怪，但它完全按照预期工作。猜猜这是 IB 中的错误