Swift 4 tableview 使用通用完成处理程序不显示数据

Question

我在使用通用函数的完成处理程序时遇到问题，似乎它不会在 UITableView 上传递任何内容，除非我在其上放置一些断点，请检查下面的代码：

public func requestGenericData<T: Decodable>(urlString: String, httpMethod: String?, token: String!, completion: @escaping(T) ->()) {
    let fullStringUrl = url + urlString
    guard let url = URL(string: fullStringUrl) else { return }
    guard let token = token else { return }
    var urlRequest = URLRequest(url: url)
    urlRequest.setValue("application/json", forHTTPHeaderField: "accept")
    urlRequest.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
    urlRequest.httpMethod = httpMethod
    URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
        if self.isInternetAvailable() {
            guard let data = data else { return }
            if let httpResponse = response as? HTTPURLResponse {
                if httpResponse.statusCode >= 200 && httpResponse.statusCode < 300 {
                    do {
                        let obj = try JSONDecoder().decode(T.self, from: data)
                        completion(obj)
                    } catch {
                        print("Error: \(String(describing: error))\n StatusCode: \(httpResponse.statusCode)")
                    }
                }
            }
        } else {
            showAlert(title: "No Internet Connect", message: "Please open your network and try again.", alertStyle: .alert, buttonTitle: "OK", buttonStyle: .default)
            return
        }
    }.resume()
}

这是将在下面的 table 查看代码中显示其结果列表的函数：

func listOfServicesMenus() {
    var jobsInCategory = [String]()
    apiHelper.requestGenericData(urlString: "nothing/more/than/a/noob", httpMethod: "GET", token: token) { (noobs: Noobs) in
        for job in jobs.jobCategories {
            jobsInCategory.append(job.name)
            for jobDetails in job.getJobs {
                jobsInCategory.append(jobDetails.name)
            }
        }
        self.listOfServices.dropView.dropDownOptions = jobsInCategory
    }
}

swift 的新手和开发中的 iOS，似乎每当我在其上设置断点时它似乎工作正常，但是如果不在其上，它不显示任何内容？

有没有人知道如何使用泛型实现正确的完成处理程序，或者我在尝试编写这段代码时遗漏了什么？

感谢那些帮助我摆脱困境的人。

更新我使用 UIView、UITableViewDelegate、UITableViewDataSource、UITableView 创建了一个所谓的 DropDownMenu（这是在 UIView 下创建的，用于正确处理约束).

更新 2

添加了 UITableView 的实现（在 UIView 下）

class dropDownView: UIView, UITableViewDelegate, UITableViewDataSource {

var dropDownOptions = [String]()
var tableView = UITableView()
var delegate: DropDownDelegate!

override init(frame: CGRect) {
    super.init(frame: frame)
    self.layer.backgroundColor = UIColor.clear.cgColor
    self.backgroundColor = UIColor.clear
    tableView.delegate = self
    tableView.dataSource = self

    tableView.translatesAutoresizingMaskIntoConstraints = false
    tableView.layer.cornerRadius = 10
    tableView.backgroundColor = UIColor(displayP3Red: 166/255, green: 203/255, blue: 69/255, alpha: 1.0)
    self.addSubview(tableView)

    tableView.leftAnchor.constraint(equalTo: self.leftAnchor).isActive = true
    tableView.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
    tableView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
    tableView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

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

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    let cell = UITableViewCell()
    cell.contentView.backgroundColor = UIColor.clear
    return dropDownOptions.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = UITableViewCell()
    cell.textLabel?.text = dropDownOptions[indexPath.row]
    cell.textLabel?.textColor = UIColor(displayP3Red: 166/255, green: 203/255, blue: 69/255, alpha: 1.0)
    cell.layer.borderColor = UIColor(displayP3Red: 112/255, green: 112/255, blue: 112/255, alpha: 1.0).cgColor
    cell.backgroundColor = UIColor(displayP3Red: 254/255, green: 252/255, blue: 215/255, alpha: 1.0)
    cell.selectionStyle = .none
    cell.textLabel?.textAlignment = .center
    return cell
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let selectedCell: UITableViewCell = tableView.cellForRow(at: indexPath)!
    selectedCell.contentView.backgroundColor = UIColor(displayP3Red: 133/255, green: 178/255, blue: 56/255, alpha: 1.0)
    selectedCell.textLabel?.textColor = UIColor.white
    self.delegate.dropDownPressed(string: self.dropDownOptions[indexPath.row])
}

func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
    let cellToDeSelect:UITableViewCell = tableView.cellForRow(at: (indexPath))!
    cellToDeSelect.contentView.layer.borderColor = UIColor(displayP3Red: 112/255, green: 112/255, blue: 112/255, alpha: 1.0).cgColor
    cellToDeSelect.contentView.backgroundColor = UIColor(displayP3Red: 254/255, green: 252/255, blue: 215/255, alpha: 1.0)
    cellToDeSelect.textLabel?.textColor = UIColor(displayP3Red: 166/255, green: 203/255, blue: 69/255, alpha: 1.0)
}

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    cell.contentView.backgroundColor = UIColor.clear
}

Answer 1

感谢您 Anil Varghese，创建了另一个将在 dropDownView class 下重新加载数据的函数并添加了这行代码：

func reloadData() {
    DispatchQueue.main.async {
        self.tableView.reloadData()
    }
}

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