在我的应用程序中，我有一个本地 SQLite 数据库并使用解析服务器 (Back4App.com)。两者的原因是允许用户设备之间的同步，如果用户删除并稍后重新安装应用程序，则可以下载数据。
我正在使用解析符号功能。他们登录后，我检查本地数据库是否有数据，如果没有，我去 Parse 并从那里下载然后将数据插入本地数据库。
奇怪的是，事件的顺序并没有像我预期的那样发生，这就是我的问题所在。
SigninVC 如下：
@IBAction func signinButton(sender: UIButton) {
activityIndicator.startAnimating()
// hides keyboard
self.view.endEditing(true)
// if username or password is empty
if usernameTextField.text!.isEmpty || passwordTextField.text!.isEmpty {
SCLAlertView().showError("Opps".localized, subTitle: "missingDetail1".localized)
}
// login functions
PFUser.logInWithUsername(inBackground: self.usernameTextField.text!, password: self.passwordTextField.text!) {
(user: PFUser?, error: Error?) -> Void in
if let error = error {
if let errorString = (error as NSError).userInfo["error"] as? String {
self.activityIndicator.stopAnimating()
NSLog(errorString);
SCLAlertView().showError("Error".localized, subTitle: "loginError".localized)
}
} else {
self.userDefault.set(PFUser.current()!.username, forKey: "username")
self.userDefault.synchronize()
self.activityIndicator.stopAnimating()
self.signInCompleted ()
}
self.rlDatabase.checkForEmtpySpeciesDetail ()
let datbaseCheckResult = self.userDefault.bool (forKey: "databaseEmpty")
if datbaseCheckResult == true {
print("No data in RLDatabase, now checking if Parse has Data")
print("1 Calling downloadFromParse function")
self.downloadFromParse { [weak self] in
print("6 Calling insertParseToSQLite function")
self?.rlDatabase.insertParseToSQLite()
}
} else {
// print("Database Not empty, no update needed")
}
}
}
func downloadFromParse (_ completion: ()->()) {
print("2 Starting downloadFromParse function")
userDefault.bool (forKey: "parseHasData")
var userCommonNameArray = parseArrayModel.userCommonNameArray
var userCommonNameESArray = parseArrayModel.userCommonNameESArray
var userCommonNameFRArray = parseArrayModel.userCommonNameFRArray
var userCommonNameDEArray = parseArrayModel.userCommonNameDEArray
var speciesNameArray = parseArrayModel.speciesNameArray
var userNotesArray = parseArrayModel.userNotesArray
let downloadQuery = PFQuery(className:"ReefLifeApps")
downloadQuery.whereKey("username", equalTo: PFUser.current()!.username!)
downloadQuery.findObjectsInBackground {(downloadedData, error) -> Void in
if error == nil {
print("3 begining downloadQuery")
for downloadData in downloadedData! {
userCommonNameArray.append(downloadData.object(forKey: "userCommonName") as! String)
userCommonNameESArray.append(downloadData.object(forKey: "userCommonNameES") as! String)
userCommonNameFRArray.append(downloadData.object(forKey: "userCommonNameFR") as! String)
userCommonNameDEArray.append(downloadData.object(forKey: "userCommonNameDE") as! String)
speciesNameArray.append(downloadData.object(forKey: "speciesName") as! String)
userNotesArray.append(downloadData.object(forKey: "userNotes") as! String)
print (speciesNameArray)
print("4 finished downloadQuery")
}
} else {
self.userDefault.set(false, forKey: "parseHasData")
// print("No username registered in parse")
}
}
if speciesNameArray.isEmpty == true {
self.userDefault.set(false, forKey: "parseHasData")
} else {
self.userDefault.set(true, forKey: "parseHasData")
}
completion()
print("5 finished downloadFromParse function")
}
RLDatabase.swift 插入到 SQLite
func insertParseToSQLite () {
print("7 begining insertParseToSQLite function")
let parseCheckResult = self.userDefault.bool (forKey: "parseHasData")
if parseCheckResult == true {
let userCommonNameArray = parseArrayModel.userCommonNameArray
let userCommonNameESArray = parseArrayModel.userCommonNameESArray
let userCommonNameFRArray = parseArrayModel.userCommonNameFRArray
let userCommonNameDEArray = parseArrayModel.userCommonNameDEArray
let speciesNameArray = parseArrayModel.speciesNameArray
let userNotesArray = parseArrayModel.userNotesArray
var statement: OpaquePointer? = nil
let update = String(format:"UPDATE RL_Species SET user_common_name = '\(userCommonNameArray)', user_common_name_fr = '\(userCommonNameFRArray)', user_common_name_es = '\(userCommonNameESArray)', user_common_name_de = '\(userCommonNameDEArray)', user_notes = '\(userNotesArray)' WHERE RL_Species.specie = '\(speciesNameArray)';")
print("8 starting SQLite3 insert")
if sqlite3_prepare_v2(database, update, -1, &statement, nil) == SQLITE_OK {
if sqlite3_step(statement) == SQLITE_DONE {
// print("Successfully updated database with Parse data.")
} else {
// print("Could NOT Update database with Parse data.")
}
} else {
// forces SQLite to send error messagesddd
let errorMessage = String.init(validatingUTF8: sqlite3_errmsg(database))!
print("update failed! \(errorMessage)")
}
sqlite3_finalize(statement)
} else {
}
print("9 finishing insertParseToSQLite function")
}
ParseArrayModel.swift
struct ParseArrayModel
{
var userCommonNameArray = [String]()
var userCommonNameESArray = [String]()
var userCommonNameFRArray = [String]()
var userCommonNameDEArray = [String]()
var speciesNameArray = [String]()
var userNotesArray = [String]()
}
可以看到，第一个调用是从 Parse 下载，然后调用 insert 函数。但是，发生的事情是它转到了 downloadFromParse，但是在
downloadQuery.findObjectsInBackground {(downloadedData, error) -> Void in
它跳过函数的其余部分，然后转到 insertToSQLite 函数，由于数组中没有数据，因此没有插入任何内容。然后它返回到 DownloadFromParse，然后抓取数据。所以，最后，所有数据都在那里，但事件的顺序错误。
完全被难住了。任何帮助是极大的赞赏。
编辑：添加 // 打印行以显示更新后的顺序。
这是控制台显示的内容：
No data in RLDatabase, now checking if Parse has Data
1 Calling downloadFromParse function
2 Starting downloadFromParse function
6 Calling insertParseToSQLite function
7 begining insertParseToSQLite function
9 finishing insertParseToSQLite function
5 finished downloadFromParse function
3 begining downloadQuery
["Acanthaster planci"]
4 finished downloadQuery