嗨，我對 swift 很陌生，并且一直在學習教程很長一段時間，最近我決定嘗試構建一個應用程式，不幸的是我遇到了這個問題并且無法弄清楚如何解決它，提前感謝任何幫助。
我正在為 speedway 構建一個排行榜應用程式，并選擇使用 firestore 更新我的應用程式中的值我目前能夠更新值并將它們顯示在 UI 中，但無法確定如何根據其他值更新值例如，同一檔案中的值需要等于獲勝 * 3 使得 3 獲勝等于 9 點目前單獨更新每個值是否有這樣做的方法提前感謝您的幫助。
我的檔案的影像
class PremierLeaugeViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
let database = Firestore.firestore()
private var service: premiership?
private var viewModel: [LeaugeViewModel] = []
var leauge = [LeaugeViewModel]() {
didSet {
DispatchQueue.main.asyncAfter(deadline: .now() 5) {
self.tableView.reloadData()
}
}
}
private var allLeauges = [LeaugeViewModel]() {
didSet {
DispatchQueue.main.async {
self.leauge = self.allLeauges
}
}
}
let tableView: UITableView = {
let tb = UITableView(frame: .zero, style: .plain)
tb.register(LeaugeHeaderTableViewHeaderView.self, forHeaderFooterViewReuseIdentifier: LeaugeHeaderTableViewHeaderView.identifier)
tb.register(LeaugeTableViewCell.self, forCellReuseIdentifier: LeaugeTableViewCell.identifier)
return tb
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(tableView)
tableView.delegate = self
tableView.dataSource = self
loadData()
title = "Premier leauge"
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
tableView.frame = view.bounds
}
func loadData() {
service = premiership()
service?.get(collectionID: "league", handler: { [weak self] leauge in
self?.allLeauges = leauge.sorted(by: { first, second in
// Everything is equal
if first.totalPoints == second.totalPoints && first.pointsDifference == second.pointsDifference && first.wins == second.wins && first.draws == second.draws && first.losses == second.losses && first.meets == second.meets {
print("This one 1")
return first.leaugePosition < second.leaugePosition
}
// Total points is the only difference
else if first.totalPoints > second.totalPoints && first.pointsDifference >= second.pointsDifference || first.pointsDifference < second.pointsDifference {
print("This one 2")
return first.totalPoints > second.totalPoints
}
// Points difference is the only difference
else if first.totalPoints >= second.totalPoints && first.pointsDifference > second.pointsDifference {
print("This one 3")
return first.pointsDifference > second.pointsDifference
}
else {
return first.pointsDifference > second.pointsDifference
}
})
})
tableView.reloadData()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return leauge.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
guard let cell = tableView.dequeueReusableCell(withIdentifier: LeaugeTableViewCell.identifier, for: indexPath) as? LeaugeTableViewCell else {
fatalError()
}
cell.configure(with: leauge[indexPath.row])
return cell
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: LeaugeHeaderTableViewHeaderView.identifier)
return header
}
func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
}
}
這是我添加的功能，用于根據其他值更改欄位
private func transaction() {
// [START transaction]
let teamRef = database.document("league/Belle Vue")
database.runTransaction({ (transaction, errorPointer) -> Any? in
var teamsDocuments: DocumentSnapshot
do {
try teamsDocuments = transaction.getDocument(teamRef)
} catch let fetchError as NSError {
errorPointer?.pointee = fetchError
return nil
}
guard let meets = teamsDocuments.data()?["meets"] as? Int else {
let error = NSError(
domain: "AppErrorDomain",
code: -1,
userInfo: [
NSLocalizedDescriptionKey: "Unable to retrieve meets from snapshot \(teamsDocuments)"
]
)
errorPointer?.pointee = error
return nil
}
guard let wins = teamsDocuments.data()?["wins"] as? Int else {
let error = NSError(
domain: "AppErrorDomain",
code: -1,
userInfo: [
NSLocalizedDescriptionKey: "Unable to retrieve wins from snapshot \(teamsDocuments)"
]
)
errorPointer?.pointee = error
return nil
}
guard let draws = teamsDocuments.data()?["draws"] as? Int else {
let error = NSError(
domain: "AppErrorDomain",
code: -1,
userInfo: [
NSLocalizedDescriptionKey: "Unable to retrieve total points from snapshot \(teamsDocuments)"
]
)
errorPointer?.pointee = error
return nil
}
guard let losses = teamsDocuments.data()?["losses"] as? Int else {
let error = NSError(
domain: "AppErrorDomain",
code: -1,
userInfo: [
NSLocalizedDescriptionKey: "Unable to retrieve losses from snapshot \(teamsDocuments)"
]
)
errorPointer?.pointee = error
return nil
}
// Note: this could be done without a transaction
// by updating the population using FieldValue.increment()
let newTotalPoints = wins * 3 draws
let newMeetsValue = wins draws losses
transaction.updateData(["total-points": newTotalPoints], forDocument: teamRef)
transaction.updateData(["meets": newMeetsValue], forDocument: teamRef)
return newTotalPoints
}) { (object, error) in
if let error = error {
print("Error updating total Points: \(error)")
} else {
print("Total Points increased to \(object!)")
}
}
// [END transaction]
}
uj5u.com熱心網友回復：
private func transaction() {
let db = Firestore.firestore()
let teamRef = db.document("league/Belle Vue")
db.runTransaction({ (transaction, errorPointer) -> Any? in
let teamsDoc: DocumentSnapshot
do {
try teamsDoc = transaction.getDocument(teamRef)
} catch let fetchError as NSError {
errorPointer?.pointee = fetchError
return nil
}
// You can bundle all of your property gets in a single guard statement or continue as you did separately;
// this is just a matter of preference.
guard let wins = teamsDoc.get("wins") as? Int,
let draws = teamsDoc.get("draws") as? Int,
let losses = teamsDoc.get("losses") as? Int else {
let error = NSError(domain: "com.yourApp",
code: 1,
userInfo: [NSLocalizedDescriptionKey: "Unable to get values from document."])
errorPointer?.pointee = error
return nil
}
let newTotalPoints = (wins * 3) draws
let newMeetsValue = wins draws losses
transaction.updateData([
"total-points": newTotalPoints
], forDocument: teamRef)
transaction.updateData([
"meets": newMeetsValue
], forDocument: teamRef)
// Update as many additional documents as needed here. You are not confined to updating only the document
// that you read from. Treat this transaction as a normal Firestore operation and do what needs to be done
// here before you return out of it.
// You can return any object or value out of this transaction if you need the object/value when the
// transaction completes. If you don't need anything out of this transaction, however, then simply return
// nil.
return newTotalPoints
}) { (newTotalPoints, error) in
if let error = error {
print("Error updating total Points: \(error.localizedDescription)")
} else if let newTotalPoints = newTotalPoints {
print("Total Points increased to \(newTotalPoints)")
}
}
}
或者，如果您在交易完成后不需要任何交易，則回傳nil：
private func transaction() {
let db = Firestore.firestore()
let teamRef = db.document("league/Belle Vue")
db.runTransaction({ (transaction, errorPointer) -> Any? in
let teamsDoc: DocumentSnapshot
do {
try teamsDoc = transaction.getDocument(teamRef)
} catch let fetchError as NSError {
errorPointer?.pointee = fetchError
return nil
}
guard let wins = teamsDoc.get("wins") as? Int,
let draws = teamsDoc.get("draws") as? Int,
let losses = teamsDoc.get("losses") as? Int else {
let error = NSError(domain: "com.yourApp",
code: 1,
userInfo: [NSLocalizedDescriptionKey: "Unable to get values from document."])
errorPointer?.pointee = error
return nil
}
let newTotalPoints = (wins * 3) draws
let newMeetsValue = wins draws losses
transaction.updateData([
"total-points": newTotalPoints
], forDocument: teamRef)
transaction.updateData([
"meets": newMeetsValue
], forDocument: teamRef)
return nil
}) { (_, error) in
if let error = error {
print("Error updating total Points: \(error.localizedDescription)")
}
}
}
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