[英]TableView not appearing in simulator?
我已经使用Single View Application模板创建了一个iOS应用程序。 运行该应用程序后,启动屏幕将显示约2秒钟,然后显示蓝色导航栏,但背景为空白。
。
我认为问题一定出在tableView的子视图上,但是我不清楚如何解决该问题。 (我没有使用情节提要,但将在某个时候实现启动屏幕。这样可以解决我的问题吗?)
import UIKit
struct Question {
var questionString: String?
var answers: [String]?
var selectedAnswerIndex: Int?
}
class QuestionController: UIViewController, UITableViewDelegate, UITableViewDataSource {
let cellId = "cellId"
let headerId = "headerId"
var tableView: UITableView?
static var questionsList: [Question] = [Question(questionString: "What is your favorite type of food?", answers: ["Sandwiches", "Pizza", "Seafood", "Unagi"], selectedAnswerIndex: nil), Question(questionString: "What do you do for a living?", answers: ["Paleontologist", "Actor", "Chef", "Waitress"], selectedAnswerIndex: nil), Question(questionString: "Were you on a break?", answers: ["Yes", "No"], selectedAnswerIndex: nil)]
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.title = "Question"
navigationController?.navigationBar.tintColor = UIColor.white
navigationItem.backBarButtonItem = UIBarButtonItem(title: "Back", style: .plain, target: nil, action: nil)
tableView = UITableView()
tableView?.dataSource = self
tableView?.delegate = self
self.view.addSubview(self.tableView!)
tableView?.register(AnswerCell.self, forCellReuseIdentifier: cellId)
tableView?.register(QuestionHeader.self, forHeaderFooterViewReuseIdentifier: headerId)
tableView?.sectionHeaderHeight = 50
tableView?.tableFooterView = UIView()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let index = navigationController?.viewControllers.index(of: self) {
let question = QuestionController.questionsList[index]
if let count = question.answers?.count {
return count
}
}
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath as IndexPath) as! AnswerCell
if let index = navigationController?.viewControllers.index(of: self) {
let question = QuestionController.questionsList[index]
cell.nameLabel.text = question.answers?[indexPath.row]
}
return cell
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: headerId) as! QuestionHeader
if let index = navigationController?.viewControllers.index(of: self) {
let question = QuestionController.questionsList[index]
header.nameLabel.text = question.questionString
}
return header
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
if let index = navigationController?.viewControllers.index(of: self) {
QuestionController.questionsList[index].selectedAnswerIndex = indexPath.item
if index < QuestionController.questionsList.count - 1 {
let questionController = QuestionController()
navigationController?.pushViewController(questionController, animated: true)
} else {
let controller = ResultsController()
navigationController?.pushViewController(controller, animated: true)
}
}
}
}
class ResultsController: UIViewController {
let resultsLabel: UILabel = {
let label = UILabel()
label.text = "Congratulations, you'd make a great Ross!"
label.translatesAutoresizingMaskIntoConstraints = false
label.textAlignment = .center
label.font = UIFont.boldSystemFont(ofSize: 14)
return label
}()
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Done", style: .plain, target: self, action: Selector(("done")))
navigationItem.title = "Results"
view.backgroundColor = UIColor.white
view.addSubview(resultsLabel)
view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": resultsLabel]))
view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": resultsLabel]))
let names = ["Ross", "Joey", "Chandler", "Monica", "Rachel", "Phoebe"]
var score = 0
for question in QuestionController.questionsList {
score += question.selectedAnswerIndex!
}
let result = names[score % names.count]
resultsLabel.text = "Congratulations, you'd make a great \(result)!"
}
func done() {
navigationController?.popToRootViewController(animated: true)
}
}
class QuestionHeader: UITableViewHeaderFooterView {
override init(reuseIdentifier: String?) {
super.init(reuseIdentifier: reuseIdentifier)
setupViews()
}
let nameLabel: UILabel = {
let label = UILabel()
label.text = "Sample Question"
label.font = UIFont.boldSystemFont(ofSize: 14)
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
func setupViews() {
addSubview(nameLabel)
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-16-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class AnswerCell: UITableViewCell {
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
let nameLabel: UILabel = {
let label = UILabel()
label.text = "Sample Answer"
label.font = UIFont.systemFont(ofSize: 14)
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
func setupViews() {
addSubview(nameLabel)
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-16-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
}
}
tableView没有框架
tableView = UITableView()
tableView.frame = self.view.bounds // this for a test change it as you want
或使用约束
正如Sh_Khan所说,您需要做的是设置一个框架。 如果这是您的永久方法,则也可以设置约束。 如果设置约束,它将自动更改高度和宽度。
tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
tableView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
您可以将此代码添加到viewDidLoad
函数中。 基本上,它为UIViewController
自动设置的视图的左侧,右侧,顶部和底部设置了约束。 这将迫使高度和宽度根据左侧,右侧,顶部和底部的位置而改变。
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