ios - 在 Swift 4 中滚动 UITableView 时如何更新 UISlider 值

Question

当我设置 slider 值时，请参阅此屏幕短

然后 tableview向下滚动然后更改值，请参阅此屏幕短

问题是当我向下滚动时值会发生变化，我已经看到了很多答案，但是在 Objective-C 中，请在 Swift 中帮助我解决这个问题。我正在使用 Xcode 9.2 和 Swift 4 非常感谢!

在这里，我将使用 CoreData，但我只想要 Slider 问题!

class ViewController: UIViewController {

    @IBOutlet var tableView: UITableView!
    var arrData = [String]()
    var studentData = [Student]()
    override func viewDidLoad() {
        super.viewDidLoad()
        studentData = DatabaseHelper.shareInstance.getAllData()
        arrData = [
            "https://is3-ssl.mzstatic.com/image/thumb/Music1/v4/53/58/26/5358265a-e225-2cfb-61da-e6cb68ea5866/source/100x100bb.jpg","https://is3-ssl.mzstatic.com/image/thumb/Music118/v4/3b/cf/4c/3bcf4c0d-a040-3d74-81e9-6ca62c3664ab/source/100x100bb.jpg",
            "https://is2-ssl.mzstatic.com/image/thumb/Music/v4/4f/a6/a3/4fa6a31a-26f0-c025-4f1c-a20da9dd4a32/source/100x100bb.jpg","https://is5-ssl.mzstatic.com/image/thumb/Music5/v4/eb/43/a3/eb43a360-d92e-7dbd-feb8-73b8496ba66f/source/100x100bb.jpg"
        ]
        for arr in arrData{
            DatabaseHelper.shareInstance.save(object: arr)
            self.tableView.reloadData()
        }
    }

}

extension ViewController: UITableViewDelegate, UITableViewDataSource{

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return studentData.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "TableViewCell", for: indexPath) as! TableViewCell
        cell.studentData = studentData[indexPath.row]
        return cell
    }

    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 80
    }

//TableViewCell

class TableViewCell: UITableViewCell {


    @IBOutlet var slider: UISlider!
    @IBOutlet var img: UIImageView!
    var studentData:Student!{
        didSet{
            let url = ImageResource(downloadURL: URL(string: studentData.photo!)!, cacheKey: studentData.photo)
            img.kf.setImage(with: url)
            slider.value = studentData.valueslider
        }
    }
    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
        DatabaseHelper.shareInstance.saveValue(object: slider.value)
    }

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        // Configure the view for the selected state
    }


    @IBAction func sliderBtnClick(_ sender: UISlider) {
        img.alpha = CGFloat(slider.value)
    }


}

//数据库助手

class DatabaseHelper{
    static let shareInstance = DatabaseHelper()

    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

    func save(object:String){
        let entity = NSEntityDescription.insertNewObject(forEntityName: "Student", into: context) as! Student
        entity.photo = object
        do{
            try context.save()
        }catch{
            print("Data not save")
        }
    }

    func saveValue(object:Float){
        let entity = NSEntityDescription.insertNewObject(forEntityName: "Student", into: context) as! Student
        entity.valueslider = object
        do{
            try context.save()
        }catch{
            print("Data not save")
        }
    }

    func getAllData() -> [Student]{
        var arrData = [Student]()
        let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "Student")
        do{
            arrData = try context.fetch(fetchRequest) as! [Student]
        }catch{
            print("Data not get")
        }
        return arrData
    }
}

数据 CoreData 类

进口基金会
导入核心数据

@objc(学生)
公共(public)课学生:NSManagedObject {

}

import Foundation
import CoreData

extension Student {

 @nonobjc public class func fetchRequest() -> NSFetchRequest<Student> {
    return NSFetchRequest<Student>(entityName: "Student")
 }

 @NSManaged public var photo: String?
 @NSManaged public var valueslider: Float

}

Answer 1

protocol SliderDelegate: class {
    func sliderValueChanged(withValue: Int, cell: TableViewCell)
}

class TableViewCell: UITableViewCell {
    weak var delegate: SliderDelegate?
    @IBAction func sliderBtnClick(_ sender: UISlider) {
       img.alpha = CGFloat(slider.value)
       delegate?.sliderValueChanged(withValue: slider.value, cell: self)  
    }

}

在您的 View Controller 的 TableView 数据源方法中

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "TableViewCell", for: indexPath) as! TableViewCell
        cell.delegate = self
        cell.studentData = studentData[indexPath.row]
        return cell
 }

并符合 Sliderdelegate

extension ViewController: SliderDelegate {
    func sliderValueChanged(withValue: Int, cell: TableViewCell) {
        guard let indexPath = yourTable.indexPath(for: cell) else {
            return
        }
        // Save Slider value to database (Database.save... your logic to update the slider value for the data at this indexPath, goes here) and then reload data like follows
        yourTable.reloadRows(at: [indexPath], with: .none)
}