无法通过下拉刷新我的 JSON 数据以在表视图控制器中刷新
Not able to refresh my JSON data through pull to refresh in tableview controller
我在通过拉动刷新我的 JSON 数据时遇到问题 refresh.When 我启动了我的应用程序，然后它显示了数据，但是当我拉动刷新时它没有刷新。
我已经实现了 Refresh Control 来刷新数据。我可以看到下拉刷新的滚轮图标，但它没有更新 JSON 数据。
这是我的代码：
struct JSONData {
let country: String
let indicename: String
let currPrice: String
let chg: String
let perChg: String
init?(dictionary: [String:Any]) {
guard let country = dictionary["Country"] as? String,
let indicename = dictionary["Indicename"] as? String,
let currPrice = dictionary["CurrPrice"] as? String,
let chg = dictionary["Chg"] as? String,
let perChg = dictionary["perChg"] as? String else {
return nil
}
self.country = country
self.indicename = indicename
self.currPrice = currPrice
self.chg = chg
self.perChg = perChg
}
}
class SouthAViewController: UIViewController,UITableViewDelegate,UITableViewDataSource,IndicatorInfoProvider {
var datas = [JSONData]()
var refreshControl = UIRefreshControl()
@IBOutlet var tableview: UITableView!
var arrowupimage : UIImage = UIImage(named : "arrowup")!
var arrowdownimage : UIImage = UIImage(named : "arrowdown")!
// I haven't shared the URL of parsing for security reasons
let url=NSURL(string:"*******************************")
let stringurl = "***************************"
override func viewDidLoad() {
super.viewDidLoad()
if #available(iOS 10.0, *) {
tableview.refreshControl = refreshControl
} else {
tableview.addSubview(refreshControl)
}
self.refreshControl.attributedTitle = NSAttributedString(string: "Pull to refresh")
self.refreshControl.addTarget(self, action: #selector(SouthAViewController.refresh), for: UIControlEvents.valueChanged)
navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.white]
self.downloadJsonWithURL()
tableview.delegate = self
tableview.dataSource = self
}
func refresh(){
self.downloadJsonWithURL()
}
// downloading JSON data to display on this class
func downloadJsonWithURL() {
let task = URLSession.shared.dataTask(with: URL(string: stringurl)!) { (data, response, error) in
if error != nil {
// print(error?.localizedDescription)
return
}
if let contdata = (try? JSONSerialization.jsonObject(with: data!, options: [])) as? [String:Any] {
if let arrJSON = contdata["data"] as? [[String:Any]] {
self.datas = arrJSON.flatMap(JSONData.init)
//Reload tableView and endRefreshing the refresh control
DispatchQueue.main.async {
self.tableview.reloadData()
self.refreshControl.endRefreshing()
}
}
}
}
task.resume()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return datas.count
}
//setting data on the table view cell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "southacell", for: indexPath) as! southacell
cell.Indicename?.text = datas[indexPath.row].indicename
cell.Country?.text = datas[indexPath.row].country
cell.CurrPrice?.text = datas[indexPath.row].currPrice
return cell
}
}
json 样本：
{ "data":[
{
"Country":"China",
"Indicename":"SZSE COMPONENT INDEX",
"date":"2017-06-23 14:53:57",
"zone":"GMT+8",
"CurrPrice":"10355.3",
"Chg":"90.07",
"PerChg":"0.88",
"prev_close":"10265.2"
},
{
"Country":"China",
"Indicename":"Shanghai Composite",
"date":"2017-06-23 14:52:54",
"zone":"GMT+8",
"CurrPrice":"3155.9",
"Chg":"8.44",
"PerChg":"0.27",
"prev_close":"3147.45"
}
]
}
不要使用 Data(contentsOf:) 从 URL 检索数据你需要使用 URLSession 和 datatask 从 URL 检索数据之后您需要在 datatask(with:) 的完成块中重新加载 tableView 和 RefreshControl 的结束动画。此外，您不需要处理多个数组，而是创建一个自定义数组 class 或 struct
struct Data {
var country: String
var indicename: String
var currPrice: String
var chg: String
var perChg: String
init?(dictionary: [String:Any]) {
guard let country = dictionary["Country"] as? String,
let indicename = dictionary["Indicename"] as? String,
let currPrice = dictionary["CurrPrice"] as? String,
let chg = dictionary["Chg"] as? String,
let perChg = dictionary["PerChg"] as? String else {
return nil
}
self.country = country
self.indicename = indicename
self.currPrice = currPrice
self.chg = chg
self.perChg = perChg
}
}
现在只声明一个类型为 [Data] 的数组，并在您的 tableView 方法中使用它。
var datas = [Data]()
现在只需使用这个单个数组来存储所有数据并显示 tableView 中的数据。
func refresh(){
self.downloadJsonWithURL()
}
func downloadJsonWithURL() {
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if error != nil {
print(error?.localizedDescription)
return
}
if let contdata = (try? JSONSerialization.jsonObject(with: data!, options: [])) as? [String:Any] {
if let arrJSON = contdata["data"] as? [[String:Any]] {
self.datas = arrJSON.flatMap(Data.init)
//Reload tableView and endRefreshing the refresh control
DispatchQueue.main.async {
self.tableView.reloadData()
self.refreshControl.endRefreshing()
}
}
}
}
task.resume()
}
//tableView methods
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return data.count
}
//setting data on the table view cell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "southacell", for: indexPath) as! southacell
let curpricefloat : Double = Double(datas[indexPath.row].currPrice)!
let Chgfloat : Double = Double(datas[indexPath.row].chg)!
let perchgfloat : Double = Double(datas[indexPath.row].perChg)!
cell.Indicename?.text = datas[indexPath.row].indicename
cell.Indicename.font = UIFont.boldSystemFont(ofSize: 19.0)
cell.Country?.text = datas[indexPath.row].country
cell.PerChg?.text = "(" + String(format: "%.2f", perchgfloat) + "%)"
cell.CurrPrice?.text = String(format: "%.2f", curpricefloat)
cell.Chg?.text = String(format: "%.2f", Chgfloat)
if Float((cell.Chg?.text)!)! < 0 {
datas[indexPath.row].chg = datas[indexPath.row].chg.replacingOccurrences(of: "-", with: "")
datas[indexPath.row].perChg = datas[indexPath.row].perChg.replacingOccurrences(of: "-", with: "")
cell.PerChg?.text = "(" + datas[indexPath.row].perChg + "%)"
cell.Chg?.text = datas[indexPath.row].chg
cell.Chg?.textColor = UIColor.red
cell.PerChg?.textColor = UIColor.red
cell.arrow?.image = UIImage(named : "arrowdown")
} else
{
cell.Chg?.textColor = UIColor.green
cell.PerChg?.textColor = UIColor.green
cell.arrow?.image = UIImage(named : "arrowup")
}
if cell.Country!.text! == "Argentina"{
cell.countryFlag?.image = UIImage(named : "argentina")
}
else if cell.Country!.text! == "Brazil"{
cell.countryFlag?.image = UIImage(named : "brazil")
}
else if cell.Country!.text! == "Peru"{
cell.countryFlag?.image = UIImage(named : "peru")
}
else{
cell.countryFlag?.image = UIImage(named : "unknown")
}
return cell
}
尝试以下操作：
override func viewDidLoad() {
super.viewDidLoad()
// MARK: Refresh control
updateData.backgroundColor = .black
updateData.tintColor = .white
updateData.attributedTitle = NSAttributedString(string: "Updating Tap
List...", attributes: [NSForegroundColorAttributeName: UIColor(red:
255.0/255.0, green: 255.0/255.0, blue: 255.0/255.0, alpha: 1.0)])
updateData.addTarget(self, action:
#selector(ViewController.loadNewData), for: UIControlEvents.valueChanged)
tapListTableView.addSubview(updateData)
tapListTableView.sendSubview(toBack: updateData)
DispatchQueue.main.async {
self.tableview.reloadData()
}
}
}
我在通过拉动刷新我的 JSON 数据时遇到问题 refresh.When 我启动了我的应用程序，然后它显示了数据，但是当我拉动刷新时它没有刷新。
我已经实现了 Refresh Control 来刷新数据。我可以看到下拉刷新的滚轮图标，但它没有更新 JSON 数据。
这是我的代码：
struct JSONData {
let country: String
let indicename: String
let currPrice: String
let chg: String
let perChg: String
init?(dictionary: [String:Any]) {
guard let country = dictionary["Country"] as? String,
let indicename = dictionary["Indicename"] as? String,
let currPrice = dictionary["CurrPrice"] as? String,
let chg = dictionary["Chg"] as? String,
let perChg = dictionary["perChg"] as? String else {
return nil
}
self.country = country
self.indicename = indicename
self.currPrice = currPrice
self.chg = chg
self.perChg = perChg
}
}
class SouthAViewController: UIViewController,UITableViewDelegate,UITableViewDataSource,IndicatorInfoProvider {
var datas = [JSONData]()
var refreshControl = UIRefreshControl()
@IBOutlet var tableview: UITableView!
var arrowupimage : UIImage = UIImage(named : "arrowup")!
var arrowdownimage : UIImage = UIImage(named : "arrowdown")!
// I haven't shared the URL of parsing for security reasons
let url=NSURL(string:"*******************************")
let stringurl = "***************************"
override func viewDidLoad() {
super.viewDidLoad()
if #available(iOS 10.0, *) {
tableview.refreshControl = refreshControl
} else {
tableview.addSubview(refreshControl)
}
self.refreshControl.attributedTitle = NSAttributedString(string: "Pull to refresh")
self.refreshControl.addTarget(self, action: #selector(SouthAViewController.refresh), for: UIControlEvents.valueChanged)
navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.white]
self.downloadJsonWithURL()
tableview.delegate = self
tableview.dataSource = self
}
func refresh(){
self.downloadJsonWithURL()
}
// downloading JSON data to display on this class
func downloadJsonWithURL() {
let task = URLSession.shared.dataTask(with: URL(string: stringurl)!) { (data, response, error) in
if error != nil {
// print(error?.localizedDescription)
return
}
if let contdata = (try? JSONSerialization.jsonObject(with: data!, options: [])) as? [String:Any] {
if let arrJSON = contdata["data"] as? [[String:Any]] {
self.datas = arrJSON.flatMap(JSONData.init)
//Reload tableView and endRefreshing the refresh control
DispatchQueue.main.async {
self.tableview.reloadData()
self.refreshControl.endRefreshing()
}
}
}
}
task.resume()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return datas.count
}
//setting data on the table view cell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "southacell", for: indexPath) as! southacell
cell.Indicename?.text = datas[indexPath.row].indicename
cell.Country?.text = datas[indexPath.row].country
cell.CurrPrice?.text = datas[indexPath.row].currPrice
return cell
}
}
json 样本：
{ "data":[
{
"Country":"China",
"Indicename":"SZSE COMPONENT INDEX",
"date":"2017-06-23 14:53:57",
"zone":"GMT+8",
"CurrPrice":"10355.3",
"Chg":"90.07",
"PerChg":"0.88",
"prev_close":"10265.2"
},
{
"Country":"China",
"Indicename":"Shanghai Composite",
"date":"2017-06-23 14:52:54",
"zone":"GMT+8",
"CurrPrice":"3155.9",
"Chg":"8.44",
"PerChg":"0.27",
"prev_close":"3147.45"
}
]
}
不要使用 Data(contentsOf:) 从 URL 检索数据你需要使用 URLSession 和 datatask 从 URL 检索数据之后您需要在 datatask(with:) 的完成块中重新加载 tableView 和 RefreshControl 的结束动画。此外，您不需要处理多个数组，而是创建一个自定义数组 class 或 struct
struct Data {
var country: String
var indicename: String
var currPrice: String
var chg: String
var perChg: String
init?(dictionary: [String:Any]) {
guard let country = dictionary["Country"] as? String,
let indicename = dictionary["Indicename"] as? String,
let currPrice = dictionary["CurrPrice"] as? String,
let chg = dictionary["Chg"] as? String,
let perChg = dictionary["PerChg"] as? String else {
return nil
}
self.country = country
self.indicename = indicename
self.currPrice = currPrice
self.chg = chg
self.perChg = perChg
}
}
现在只声明一个类型为 [Data] 的数组，并在您的 tableView 方法中使用它。
var datas = [Data]()
现在只需使用这个单个数组来存储所有数据并显示 tableView 中的数据。
func refresh(){
self.downloadJsonWithURL()
}
func downloadJsonWithURL() {
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if error != nil {
print(error?.localizedDescription)
return
}
if let contdata = (try? JSONSerialization.jsonObject(with: data!, options: [])) as? [String:Any] {
if let arrJSON = contdata["data"] as? [[String:Any]] {
self.datas = arrJSON.flatMap(Data.init)
//Reload tableView and endRefreshing the refresh control
DispatchQueue.main.async {
self.tableView.reloadData()
self.refreshControl.endRefreshing()
}
}
}
}
task.resume()
}
//tableView methods
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return data.count
}
//setting data on the table view cell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "southacell", for: indexPath) as! southacell
let curpricefloat : Double = Double(datas[indexPath.row].currPrice)!
let Chgfloat : Double = Double(datas[indexPath.row].chg)!
let perchgfloat : Double = Double(datas[indexPath.row].perChg)!
cell.Indicename?.text = datas[indexPath.row].indicename
cell.Indicename.font = UIFont.boldSystemFont(ofSize: 19.0)
cell.Country?.text = datas[indexPath.row].country
cell.PerChg?.text = "(" + String(format: "%.2f", perchgfloat) + "%)"
cell.CurrPrice?.text = String(format: "%.2f", curpricefloat)
cell.Chg?.text = String(format: "%.2f", Chgfloat)
if Float((cell.Chg?.text)!)! < 0 {
datas[indexPath.row].chg = datas[indexPath.row].chg.replacingOccurrences(of: "-", with: "")
datas[indexPath.row].perChg = datas[indexPath.row].perChg.replacingOccurrences(of: "-", with: "")
cell.PerChg?.text = "(" + datas[indexPath.row].perChg + "%)"
cell.Chg?.text = datas[indexPath.row].chg
cell.Chg?.textColor = UIColor.red
cell.PerChg?.textColor = UIColor.red
cell.arrow?.image = UIImage(named : "arrowdown")
} else
{
cell.Chg?.textColor = UIColor.green
cell.PerChg?.textColor = UIColor.green
cell.arrow?.image = UIImage(named : "arrowup")
}
if cell.Country!.text! == "Argentina"{
cell.countryFlag?.image = UIImage(named : "argentina")
}
else if cell.Country!.text! == "Brazil"{
cell.countryFlag?.image = UIImage(named : "brazil")
}
else if cell.Country!.text! == "Peru"{
cell.countryFlag?.image = UIImage(named : "peru")
}
else{
cell.countryFlag?.image = UIImage(named : "unknown")
}
return cell
}
尝试以下操作：
override func viewDidLoad() {
super.viewDidLoad()
// MARK: Refresh control
updateData.backgroundColor = .black
updateData.tintColor = .white
updateData.attributedTitle = NSAttributedString(string: "Updating Tap
List...", attributes: [NSForegroundColorAttributeName: UIColor(red:
255.0/255.0, green: 255.0/255.0, blue: 255.0/255.0, alpha: 1.0)])
updateData.addTarget(self, action:
#selector(ViewController.loadNewData), for: UIControlEvents.valueChanged)
tapListTableView.addSubview(updateData)
tapListTableView.sendSubview(toBack: updateData)
DispatchQueue.main.async {
self.tableview.reloadData()
}
}
}