你好，我有两个 View Controller ，第一个带有步进器
var steppers : UIStepper?
@IBOutlet weak var hourLabel: UILabel!
@IBAction func stepper(_ sender: UIStepper) {
hourLabel.text = String(sender.value)
}
第二个带有 tableView
import UIKit
import AVFoundation
class SelectClass: UIViewController, UITableViewDelegate, UITableViewDataSource {
@IBOutlet weak var tableView: UITableView!
var list : [QCategoryy] = [QCategoryy]()
var audioPlayer : AVAudioPlayer!
var limit = 3
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
tableView.allowsMultipleSelection = true
self.title = "Categories"
list = NearbyPlaces.getCategories()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
list.sort() { $0.views > $1.views}
tableView.reloadData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func backTapp(_ sender: Any) {
let audioUrl = NSURL.fileURL(withPath: Bundle.main.path(forResource: "pop_drip", ofType: "m4a")!)
do{
try AVAudioSession.sharedInstance().setActive(true)
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
try audioPlayer = AVAudioPlayer(contentsOf: audioUrl)
audioPlayer.prepareToPlay()
audioPlayer.play()
}
catch _ as NSError
{
}
dismiss(animated: true, completion: nil)
}
@IBAction func doneTapp(_ sender: Any) {
let audioUrl = NSURL.fileURL(withPath: Bundle.main.path(forResource: "pop_drip", ofType: "m4a")!)
do{
try AVAudioSession.sharedInstance().setActive(true)
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
try audioPlayer = AVAudioPlayer(contentsOf: audioUrl)
audioPlayer.prepareToPlay()
audioPlayer.play()
}
catch _ as NSError
{
}
self.performSegue(withIdentifier: nearbySearchSegueIdentifier, sender: nil)
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return list.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let identifier = "CATEGORY_CELL"
let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath)
let selectedIndexPaths = tableView.indexPathsForSelectedRows
let rowIsSelected = selectedIndexPaths != nil && selectedIndexPaths!.contains(indexPath)
/* cell.accessoryType = rowIsSelected ? .checkmark : .none */
cell.accessoryType = list[indexPath.row].isSelected ? .checkmark : .none
cell.textLabel?.text = list[indexPath.row].name
return cell
}
let nearbySearchSegueIdentifier = "goToMcourse"
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let cell = tableView.cellForRow(at: indexPath)!
cell.accessoryType = .checkmark
/* self.performSegue(withIdentifier: nearbySearchSegueIdentifier, sender: list[indexPath.row]) */
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
let cell = tableView.cellForRow(at: indexPath)!
cell.accessoryType = .none
}
func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
if let sr = tableView.indexPathsForSelectedRows {
if sr.count == limit {
let alertController = UIAlertController(title: "Oops", message:
"You are limited to \(limit) selections", preferredStyle: .alert)
alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: {action in
}))
self.present(alertController, animated: true, completion: nil)
return nil
}
}
return indexPath
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == nearbySearchSegueIdentifier {
guard let category = sender as? QCategoryy else {
return
}
if let selectedRows = tableView.indexPathsForSelectedRows {
if let vc = segue.destination as? CourseClass2 {
vc.category = category
}
}
}
}
}
extension QCategoryy {
private static let ketPrefix = "category-"
var views:Int {
get {
return UserDefaults.standard.integer(forKey: QCategoryy.ketPrefix + name)
}
}
func markView() {
UserDefaults.standard.set(views + 1, forKey: QCategoryy.ketPrefix + name)
}
}
在此 tableView 中，我可以选择多个单元格并使用 var 添加对选择的限制
var limit = 3
和函数
func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
if let sr = tableView.indexPathsForSelectedRows {
if sr.count == limit {
let alertController = UIAlertController(title: "Oops", message:
"You are limited to \(limit) selections", preferredStyle: .alert)
alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: {action in
}))
self.present(alertController, animated: true, completion: nil)
return nil
}
}
return indexPath
}
但我想做的是使用第一个 viewController 中的步进器在选择 tableView (在第二个 viewController 中)时添加限制，例如 
我该怎么做？
最佳答案
在带有步进器的 VC 中，覆盖 prepareForSegue:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let vc = segue.destination as? SelectClass {
vc.limit = Int(stepper.value)
}
}
编辑:您需要使步进器成为 VC 的导出，首先将声明更改为:
@IBOutlet var stepper: UIStepper!
在 Storyboard中，右键单击 View Controller (带有黄色图标的 Controller ):
然后出现:
看到“ socket ”下的步进器了吗？从步进器旁边的圆圈拖动到 Storyboard 上的步进器:
关于ios - TableView限制使用(Swift)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46886275/