我对整体编码很陌生，学习swift 3，我正在尝试集成一个按钮，如果按下它会"星号"。因此，目前它会写入Firebase，状态为"true"，如果按下，还会写入更多数据。
问题是它只在按下 2 次时起作用。但在那之后它工作得很好...(编辑：通过"不起作用"，我的意思是它不会在我第一次按下时将图像更新为"填充 64x64"。我刚刚检查了Firebase，似乎它创建了一个记录，我第一次按下，但把它放在收藏夹=假(
一些更有经验的程序员可以帮助我了解问题所在吗？
这是来自"星号"按钮的代码：
/*
==========================================================================================
//MARK: Start of code that stars your whisky Firebase
==========================================================================================
*/
var isStarred = UserDefaults.standard.bool(forKey: "isStarred")
@IBAction func starButton(_ sender: Any) {
//loads info for query
let currentUserID = self.user?.uid
let realIndex:Int? = detailWhisky?.realIndex
let realIndex2 = "(realIndex!)"
//executes query
let starRef2 = FIRDatabase.database().reference().child("Starred").child(currentUserID!).child(realIndex2)
//print("booyah")
//changes state of button and loads true/false to Firebase
if isStarred == true {
let image = UIImage(named: "star64x64.png")
(sender as AnyObject).setImage(image, for: UIControlState.normal)
let favourite = ["favourite": false, "realIndex": detailWhisky?.realIndex, "shortName": self.title, "distillery": distilleryLabel.text] as [String : Any]
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
} })}
else {
let image = UIImage(named: "filled 64x64.png")
(sender as AnyObject).setImage(image, for: UIControlState.highlighted)
let favourite = ["favourite": true, "realIndex": detailWhisky?.realIndex, "shortName": self.title, "distillery": distilleryLabel.text] as [String : Any]
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
} })}
isStarred = !isStarred
UserDefaults.standard.set(isStarred, forKey: "isStarred")
UserDefaults.standard.synchronize()
}
然后为了填充，我在ViewDidLoad中运行"starred(("。
override func viewDidLoad() {
super.viewDidLoad()
configureView() //populates text fields etc.
starred() // populates the starred star
}
"starred((" 函数如下所示：
//func starred(likeButton: UIButton) {
func starred() {
//initalize to make query work
let currentUserID = self.user?.uid //to get userID
let realIndex:Int? = detailWhisky?.realIndex
let realIndex2 = "(realIndex!)" //realIndex
//query to firebase
starRef.child(currentUserID!).queryOrdered(byChild: "realIndex").queryEqual(toValue: realIndex).observe(.value, with: { snapshot in
if snapshot.value is NSNull {
print("Ingen treff i stjaernesoeket")
} else {
for child in snapshot.children {
let newStarred = Favourite(snapshot: child as! FIRDataSnapshot)
self.detailStarred = newStarred
//print(newStarred)
var boolStorage: Bool? = self.detailStarred?.favourite
if let boolStorage = boolStorage, boolStorage {
// executes when booleanValue is true
print("unwrapped boolStorage: '(boolStorage)'")
let myImage = UIImage(named: "filled 64x64.png")
self.starButton.setImage(myImage, for: UIControlState.normal)
}
else {
print("not a favourite")}
}}})
}
数据结构如下所示：
struct Favourite {
var key: String?
let ref: FIRDatabaseReference?
var favourite: Bool?
var currentUserID: String?
var realIndex: Int?
var shortName: String?
let distillery: String?
init(key: String = "", favourite: Bool, currentUserID: String, realIndex: Int, shortName: String, distillery: String){
self.key = key
self.ref = nil
self.favourite = favourite
self.currentUserID = currentUserID
self.realIndex = realIndex
self.shortName = shortName
self.distillery = distillery
}
init(snapshot: FIRDataSnapshot) {
key = snapshot.key
ref = snapshot.ref
let snapshotValue = snapshot.value as! [String: AnyObject]
favourite = snapshotValue["favourite"] as? Bool
currentUserID = snapshotValue["currentUserID"] as? String
realIndex = snapshotValue["realIndex"] as? Int
shortName = snapshotValue["shortName"] as? String
distillery = snapshotValue["distillery"] as? String
}
func toAnyObject() -> Any {
return [
"favourite": favourite as Any,
"currentUserID": currentUserID as Any,
"realIndex": realIndex as Any,
"shortName": shortName as Any,
"distillery": distillery as Any,
]
}
}
我找到了一个适合我的解决方案。我相信它可以更优雅地处理，但我正在发布它，以防它可以帮助其他人。
解决方案是添加一个额外的变量"buttonStarred"，如果之前没有被收藏，它会从 Firebase 获取一个值。然后，在按下"带星标的按钮"时，我首先检查此变量，然后再继续使用现有代码。
从 Firebase 加载收藏夹状态的 func。 现在，它为"按钮Starred"变量提供"缺失"值。
func starred() {
//initalize to make query work
let currentUserID = self.user?.uid //to get userID
let realIndex:Int? = detailWhisky?.realIndex
//query to firebase
starRef.child(currentUserID!).queryOrdered(byChild: "realIndex").queryEqual(toValue: realIndex).observe(.value, with: { snapshot in
if snapshot.value is NSNull {
print("Ingen treff i stjaernesoeket")
self.buttonStarred = "missing"
print(self.buttonStarred as Any)
} else { for child in snapshot.children {
let newStarred = Favourite(snapshot: child as! FIRDataSnapshot)
self.detailStarred = newStarred
//print(newStarred)
var boolStorage: Bool? = self.detailStarred?.favourite
if let boolStorage = boolStorage, boolStorage {
// executes when booleanValue is true
let myImage = UIImage(named: "filled 64x64.png")
self.starButton.setImage(myImage, for: UIControlState.normal)
self.buttonStarred = "fav"
print(self.buttonStarred)
}
else {
//self.detailStarred?.favourite = true
print("not a favourite")
self.buttonStarred = "notFav"
print(self.buttonStarred as Any)
}
}}})
}
然后我的按钮会执行此额外检查：
if self.buttonStarred == "missing" { //extra check to avoid false to be the value for first time creation in FireBase
let favourite = ["favourite": true, "realIndex": detailWhisky?.realIndex as Any, "shortName": self.title as Any, "distillery": distilleryLabel.text as Any, "searchText": searchText as Any] as [String : Any] //21.09.0217
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
} })}
现在它起作用了。它立即填充按钮，因此对用户来说是无缝的，并将正确的状态写入Firebase。
下面的完整按钮代码，以防它可以帮助某人：
@IBAction func starButton(_ sender: Any) {
//loads info for query
let currentUserID = self.user?.uid
let realIndex:Int? = detailWhisky?.realIndex
let realIndex2 = "(realIndex!)"
let searchText: String? = ("(self.distilleryLabel.text)"+"(self.title)"+"(self.brandNameLabel.text)")//creates searchText
let filledImage = UIImage(named: "filled 64x64.png") //21.09.0217
//executes query
let starRef2 = FIRDatabase.database().reference().child("Starred").child(currentUserID!).child(realIndex2)
//print("booyah")
self.starButton.setImage(filledImage, for: UIControlState.normal)//21.09.0217
let favourite = ["favourite": true, "realIndex": detailWhisky?.realIndex as Any, "shortName": self.title as Any, "distillery": distilleryLabel.text as Any, "searchText": searchText as Any] as [String : Any] //21.09.0217
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
}})
//changes state of button and loads true/false to Firebase
isStarred = !isStarred
if self.buttonStarred == "missing" { //extra check to avoid false to be the value for first time creation in FireBase
let favourite = ["favourite": true, "realIndex": detailWhisky?.realIndex as Any, "shortName": self.title as Any, "distillery": distilleryLabel.text as Any, "searchText": searchText as Any] as [String : Any] //21.09.0217
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
} })}
else if isStarred == false {
let image = UIImage(named: "star64x64.png")
(sender as AnyObject).setImage(image, for: UIControlState.normal)
let favourite = ["favourite": false, "realIndex": detailWhisky?.realIndex as Any, "shortName": self.title as Any, "distillery": distilleryLabel.text as Any, "searchText": searchText as Any] as [String : Any]
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
} })}
else {
let image = UIImage(named: "filled 64x64.png")
(sender as AnyObject).setImage(image, for: UIControlState.highlighted)
let favourite = ["favourite": true, "realIndex": detailWhisky?.realIndex as Any, "shortName": self.title as Any, "distillery": distilleryLabel.text as Any, "searchText": searchText as Any] as [String : Any]
starRef2.updateChildValues(favourite, withCompletionBlock: { (err, ref) in
if err != nil {
print(err as Any)
return
} })}
//isStarred = !isStarred
UserDefaults.standard.set(isStarred, forKey: "isStarred")
UserDefaults.standard.synchronize()
}