IOS - 从 Firebase 解析对象 - 下载完成前的代码 运行
IOS - Parsing objects from Firebase - Code running before download is completed
我正在尝试将来自 Firebase 的数据解析为一个对象数组，并在完成后显示数组中第一个对象的文本。但是，我无法使用 out/find 解决方案来在下载完成之前停止继续执行代码。因此它继续将用户的完成更新为 true，而不显示文本。这是原样的功能，下载和附加到数组工作正常，但它在完成之前跳到 displayNextInSeries()...
func parseSeries (ref: String) {
FIRDatabase.database().reference().child("library").child("series").child(ref).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let pushSeriesDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let push = PUSH_SERIES(pushKey: key, pushSeriesData: pushSeriesDict)
self.seriesArray.append(push)
}
}
}
})
print("\(ref) Series Count: \(self.seriesArray.count)")
displayNextInSeries()
}
系列函数中的下一个显示看到 seriesArray.count = 0，因此它不会更新 texLbl:
func displayNextInSeries() {
if seriesProgress < seriesArray.count {
animateProgress(current: seriesProgress, total: seriesArray.count)
currentPUSH_SERIES = seriesArray[seriesProgress]
currentPUSH_SERIES.text = personaliseText(text: currentPUSH_SERIES.text)
textLbl.animateUpdate(currentPUSH_SERIES.text, oldText: previousText)
titleLbl.text = "\(currentPUSH_SERIES.title!)"
previousText = currentPUSH_SERIES.text
seriesProgress += 1
} else {
animateProgress(current: sessionProgress, total: sessionTarget)
titleLbl.text = ""
greetingPush()
seriesPlay = false
seriesProgress = 0
user.updateProgress(seriesName)
print(user.progress)
}
}
我这里可能做错了一些根本性的事情。非常需要您的帮助，非常感谢！谢谢，马特
observeSingleOfEvent 是一个异步调用，调用 completionBlock 中的函数将解决它，问题是你的打印函数甚至在 observeSingleOfEvent 完成下载数据之前就被调用了 :-
func parseSeries (ref: String) {
FIRDatabase.database().reference().child("library").child("series").child(ref).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let pushSeriesDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let push = PUSH_SERIES(pushKey: key, pushSeriesData: pushSeriesDict)
self.seriesArray.append(push)
print("\(ref) Series Count: \(self.seriesArray.count)")
displayNextInSeries()
}
}
}
})
}
我正在尝试将来自 Firebase 的数据解析为一个对象数组，并在完成后显示数组中第一个对象的文本。但是，我无法使用 out/find 解决方案来在下载完成之前停止继续执行代码。因此它继续将用户的完成更新为 true，而不显示文本。这是原样的功能，下载和附加到数组工作正常，但它在完成之前跳到 displayNextInSeries()...
func parseSeries (ref: String) {
FIRDatabase.database().reference().child("library").child("series").child(ref).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let pushSeriesDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let push = PUSH_SERIES(pushKey: key, pushSeriesData: pushSeriesDict)
self.seriesArray.append(push)
}
}
}
})
print("\(ref) Series Count: \(self.seriesArray.count)")
displayNextInSeries()
}
系列函数中的下一个显示看到 seriesArray.count = 0，因此它不会更新 texLbl:
func displayNextInSeries() {
if seriesProgress < seriesArray.count {
animateProgress(current: seriesProgress, total: seriesArray.count)
currentPUSH_SERIES = seriesArray[seriesProgress]
currentPUSH_SERIES.text = personaliseText(text: currentPUSH_SERIES.text)
textLbl.animateUpdate(currentPUSH_SERIES.text, oldText: previousText)
titleLbl.text = "\(currentPUSH_SERIES.title!)"
previousText = currentPUSH_SERIES.text
seriesProgress += 1
} else {
animateProgress(current: sessionProgress, total: sessionTarget)
titleLbl.text = ""
greetingPush()
seriesPlay = false
seriesProgress = 0
user.updateProgress(seriesName)
print(user.progress)
}
}
我这里可能做错了一些根本性的事情。非常需要您的帮助，非常感谢！谢谢，马特
observeSingleOfEvent 是一个异步调用，调用 completionBlock 中的函数将解决它，问题是你的打印函数甚至在 observeSingleOfEvent 完成下载数据之前就被调用了 :-
func parseSeries (ref: String) {
FIRDatabase.database().reference().child("library").child("series").child(ref).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let pushSeriesDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let push = PUSH_SERIES(pushKey: key, pushSeriesData: pushSeriesDict)
self.seriesArray.append(push)
print("\(ref) Series Count: \(self.seriesArray.count)")
displayNextInSeries()
}
}
}
})
}