使用 SwiftUI 和 FireStore 更新文本
Updating Text Using SwiftUI and FireStore
我在我的应用程序中存储了一个名为月小时的值,用于跟踪一个人使用应用程序的时间并将其显示在一行文本中。文本如果是 Swift UI 中堆栈的一部分,但是一旦从中查询了信息,我就无法弄清楚如何更新文本 我已经尝试了很多方法来制作这个从结构到 类 再到使用 @State。
这只是我尝试过的最新方法,但没有用,如果有人能提供帮助,我们将不胜感激。
let db = Firestore.firestore()
class Month {
var monthHours = "0"
func getMonthHours() {
db.addSnapshotListener(. //Im removing the actual query part to keep that private but the print statement below confirms the query is not the issue.
{ (docSnapShot, err) in
if let e = err {
print("There was an error retrieving the monthly hours:\n\(e.localizedDescription)")
} else {
let data = docSnapShot?.data()
if let h = data?[K.FStore.monthHoursField] as? Double {
self.monthHours = String(h.rounded())
print("These are the hours:\n\(self.monthHours)")
}
}
})
}
func getMonth() -> String {
let date = Date()
let formatter = DateFormatter()
formatter.dateFormat = "MMMM yyyy"
let result = formatter.string(from: date)
return result
}
init() {
getMonthHours()
}
}
struct ChartView : View {
@State private var month = Month()
//Struct variables
var body : some View {
ZStack {
Color(UIColor(named: K.BrandColors.grey)!).edgesIgnoringSafeArea(.all)
VStack {
Text("HOURS THIS MONTH \(month.monthHours)")
.font(.system(size: 18))
.fontWeight(.heavy)
}
}
}
这概述了一种可能的方法。症结在于处理异步函数"getMonthHours"。您需要等到它完成提取后才能使用结果。
class Month {
var monthHours = "0"
// async fetch the month hours from Firestore, ... error handling todo
static func getMonthHours(handler: @escaping (String) -> Void) {
db.addSnapshotListener{ (docSnapShot, err) in
if let e = err {
print("There was an error retrieving the monthly hours:\n\(e.localizedDescription)")
return handler("") // should return some error here .... todo
} else {
if let data = docSnapShot?.data(),
let h = data?[K.FStore.monthHoursField] as? Double {
// return the result
return handler(String(h.rounded()))
} else {
return handler("") // should return some error here .... todo
}
}
}
}
func getMonth() -> String {
let date = Date()
let formatter = DateFormatter()
formatter.dateFormat = "MMMM yyyy"
let result = formatter.string(from: date)
return result
}
init() { }
}
struct ChartView : View {
@State private var monthHours = ""
var body : some View {
ZStack {
Color(UIColor(named: K.BrandColors.grey)!).edgesIgnoringSafeArea(.all)
VStack {
Text("HOURS THIS MONTH \(monthHours)")
.font(.system(size: 18))
.fontWeight(.heavy)
}
}.onAppear(perform: loadData)
}
}
func loadData() {
// when the fetching is done it will update the view
Month.getMonthHours() { hours in
self.monthHours = hours
}
}
我在我的应用程序中存储了一个名为月小时的值,用于跟踪一个人使用应用程序的时间并将其显示在一行文本中。文本如果是 Swift UI 中堆栈的一部分,但是一旦从中查询了信息,我就无法弄清楚如何更新文本 我已经尝试了很多方法来制作这个从结构到 类 再到使用 @State。
这只是我尝试过的最新方法,但没有用,如果有人能提供帮助,我们将不胜感激。
let db = Firestore.firestore()
class Month {
var monthHours = "0"
func getMonthHours() {
db.addSnapshotListener(. //Im removing the actual query part to keep that private but the print statement below confirms the query is not the issue.
{ (docSnapShot, err) in
if let e = err {
print("There was an error retrieving the monthly hours:\n\(e.localizedDescription)")
} else {
let data = docSnapShot?.data()
if let h = data?[K.FStore.monthHoursField] as? Double {
self.monthHours = String(h.rounded())
print("These are the hours:\n\(self.monthHours)")
}
}
})
}
func getMonth() -> String {
let date = Date()
let formatter = DateFormatter()
formatter.dateFormat = "MMMM yyyy"
let result = formatter.string(from: date)
return result
}
init() {
getMonthHours()
}
}
struct ChartView : View {
@State private var month = Month()
//Struct variables
var body : some View {
ZStack {
Color(UIColor(named: K.BrandColors.grey)!).edgesIgnoringSafeArea(.all)
VStack {
Text("HOURS THIS MONTH \(month.monthHours)")
.font(.system(size: 18))
.fontWeight(.heavy)
}
}
}
这概述了一种可能的方法。症结在于处理异步函数"getMonthHours"。您需要等到它完成提取后才能使用结果。
class Month {
var monthHours = "0"
// async fetch the month hours from Firestore, ... error handling todo
static func getMonthHours(handler: @escaping (String) -> Void) {
db.addSnapshotListener{ (docSnapShot, err) in
if let e = err {
print("There was an error retrieving the monthly hours:\n\(e.localizedDescription)")
return handler("") // should return some error here .... todo
} else {
if let data = docSnapShot?.data(),
let h = data?[K.FStore.monthHoursField] as? Double {
// return the result
return handler(String(h.rounded()))
} else {
return handler("") // should return some error here .... todo
}
}
}
}
func getMonth() -> String {
let date = Date()
let formatter = DateFormatter()
formatter.dateFormat = "MMMM yyyy"
let result = formatter.string(from: date)
return result
}
init() { }
}
struct ChartView : View {
@State private var monthHours = ""
var body : some View {
ZStack {
Color(UIColor(named: K.BrandColors.grey)!).edgesIgnoringSafeArea(.all)
VStack {
Text("HOURS THIS MONTH \(monthHours)")
.font(.system(size: 18))
.fontWeight(.heavy)
}
}.onAppear(perform: loadData)
}
}
func loadData() {
// when the fetching is done it will update the view
Month.getMonthHours() { hours in
self.monthHours = hours
}
}