ios - 第一次按按钮不起作用，但第二次就可以了

Question

我对整体编码还很陌生，正在学习 swift 3，并且我正在尝试集成一个按下时会“加星”的按钮。因此，目前它会向 Firebase 写入状态“true”，以及按下时的更多数据。

问题是它只能在按下两次时起作用。但在那之后它就完美地工作了......(编辑:“不起作用”我的意思是，我第一次按下时它不会将图像更新为“填充64x64”。我刚刚 checkin Firebase，它似乎在我第一次按下时创建了一条记录，但是将其设为最爱= false)

一些更有经验的编码员可以帮助我了解问题所在吗？

这是“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,
    ]
}

}

Answer 1

我找到了适合我的解决方案。我确信可以更优雅地处理它，但我将其发布，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”，如果之前未收藏该变量，该变量将从 Firebase 获取值。然后，当按下“加星标的按钮”时，我首先检查此变量，然后再继续现有代码。

从 Firebase 加载收藏夹状态的函数。现在它为“buttonStarred”变量提供了“missing”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)
                }
            }}})
}

然后我的按钮会进行额外的检查:

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
    } })}

现在可以了。它会立即填充按钮，因此对于用户来说是无缝的，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()
}