How to fix 'data of UITableViewCell exchange'? - ios

Question

My certain two rows of data of UITableViewCell exchange, and this is how it looks.
The row data after exchanged are the right, and they're wrong before exchanged.
And I'm sorry for not have enough reputation to post .gif image.
Is there any way to avoid the data exchange to the wrong row?
my-data-changes-in-uitableviewcell-when-i-scroll-down-and-get-back
ios-uitableview-mixes-up-data-when-scrolling-too-fast
swift-user-input-mixed-up-when-uitableview-reuses-cells
swift-2-tableview-scrolling-changes-data
The links of problems above seem to be related to mine, but I think my problem is not caused by scrolling.
I setup UITableViewCell with DispatchQueue.global(qos: .background).async, and this function is inside the cell itself.
--SensorRecordTableViewCell (UITableViewCell)--
func getNewLiveInfo(shedId: String, sensorCategory: String) {
DispatchQueue.global(qos: .background).async {
let id = self.shedId.cString(using: .utf8)
let shed_id = UnsafeMutablePointer(mutating: id)
let category = self.sensorCategory.cString(using: .utf8)
let sensor_category = UnsafeMutablePointer(mutating: category)
if let data = getliveInfo(shed_id, sensor_category) {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
// record_id, sensor_id, sensor_category, sensor_value, read_time
self.sensorRecord.recordId = String(cString: data.pointee!)
self.sensorRecord.sensorId = String(cString: (data+1).pointee!)
self.sensorRecord.sensorCategory = String(cString: (data+2).pointee!)
self.sensorRecord.value = Double(String(cString: (data+3).pointee!))
self.sensorRecord.time = formatter.date(from: String(cString: (data+4).pointee!))
DispatchQueue.main.async {
self.setValueAndTime()
}
data.deallocate()
}
}
}
And call the function above from func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath)
--UITableViewDelegate, UITableViewDataSource--
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
var cell = cell as! SensorRecordTableViewCell
cell.getNewLiveInfo(shedId: shed.id!, sensorCategory: config.sensorRecordOrder[indexPath.row])
}
Finally, I setup the cell from func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: sensorCellId, for: indexPath) as! SensorRecordTableViewCell
cell.setUpView(shedId: shed.id!, sensorCategory: config.sensorRecordOrder[indexPath.row])
return cell
}
Is there any way to avoid the data exchange to the wrong row?

Answer 1

Here is a simple example to show what it should looks like,
hope it helps.
class SensorRecord {
var recordID: Int = 0
var sensorID: Int = 0
}
class ViewController: UIViewController {
private var dataSource = [SensorRecord]()
override func viewDidLoad() {
super.viewDidLoad()
// request infos from your server
getNewLiveInfo(completion: { (sensorRecords)
// after the request success, reload data
self.dataSource = sensorRecords
self.tableView.reloadData()
})
}
}
// MARK: UITableViewDataSource
extension ViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return dataSource.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ID", for: indexPath)
// let your cell to show datas from your server
let sensorRecord = dataSource[indexPath.row]
cell.update(with: sensorRecord)
return cell
}
}