使用Firebase异步字典创建对象数组下载（Swift）
问题描述：
我是新来的Swift。我一直无法下载Firebase字典并将它们转换为一组对象。使用Firebase异步字典创建对象数组下载（Swift）
我在做什么错误的语法如下？我花了两天的时间试图弄清楚这一点。以下给我一个索引超出范围错误。这是因为Firebase字典还没有完成下载，或者是我的for循环系列错误？也许都是？谢谢。
// Array of Location Objects
var locationsArray:[Location] = [Location]()
var ref = Firebase(url: "<MYFIREBASEURL>")
var dictionaryOfRecommendations:[NSDictionary] = [NSDictionary]()
var currentlyConstructingLocation:Location = Location()
func getLocationData() {
let titleRef = self.ref.childByAppendingPath("events")
titleRef.observeSingleEventOfType(.Value, withBlock: { snapshot in
var tempDict = [NSDictionary]()
for item in snapshot.children {
let child = item as! FDataSnapshot
let dict = child.value as! NSDictionary
tempDict.append(dict)
}
self.dictionaryOfRecommendations = tempDict
})
// Parse data from Firebase
// Loop through each dictionary and assign values to location object
var index:Int
for index in 0...dictionaryOfRecommendations.count {
// Current Json dictionary
let jsonDictionary:NSDictionary = self.dictionaryOfRecommendations[index]
self.currentlyConstructingLocation.title = jsonDictionary["title"] as! String!
self.currentlyConstructingLocation.locationsLatitudeArray = jsonDictionary["latitude"] as! Double
self.currentlyConstructingLocation.locationsLongitudeArray = jsonDictionary["longitude"] as! Double
// Append to Locations Array and start new Location
self.locationsArray.append(currentlyConstructingLocation)
self.currentlyConstructingLocation = Location()
}
// Notify the MainViewController that the Locations are ready.
...
}
答
下面是上述基础上周杰伦的有益的指导问题的更新正确的代码：
//模型下载位置数据的事件。
//Firebase reference
var ref = Firebase(url: "<MYFIREBASEURL")
var locationsArray:[Location] = [Location]()
var dictionaryOfRecommendations:[NSDictionary] = [NSDictionary]()
var currentlyConstructingLocation:Location = Location()
func getLocationData() {
let titleRef = self.ref.childByAppendingPath("events")
titleRef.observeSingleEventOfType(.Value, withBlock: { snapshot in
var tempDict = [NSDictionary]()
for item in snapshot.children {
let child = item as! FDataSnapshot
let dict = child.value as! NSDictionary
tempDict.append(dict)
}
self.dictionaryOfRecommendations = tempDict
self.ParseFirebaseData()
})
}
func ParseFirebaseData() {
// Parse data from Firebase
// Loop through each dictionary and assign values to location object
var index:Int
for index in 0...dictionaryOfRecommendations.count - 1 {
// Current Json dictionary
let jsonDictionary:NSDictionary = self.dictionaryOfRecommendations[index]
self.currentlyConstructingLocation.title = jsonDictionary["title"] as! String!
self.currentlyConstructingLocation.locationsLatitudeArray = jsonDictionary["latitude"] as! Double
self.currentlyConstructingLocation.locationsLongitudeArray = jsonDictionary["longitude"] as! Double
// Append to Locations Array and start new Location
self.locationsArray.append(currentlyConstructingLocation)
self.currentlyConstructingLocation = Location()
}
}
Firebase是异步的 - 只有在实际拥有该数据之后，您才能对Firebase数据进行操作。使用您的代码，通过每个字典代码的循环将在firebase返回其数据之前执行WAY;您的应用中的本地代码比互联网快得多！解决方案是在Firebase withBlock部分内处理数据。您可以将for索引保留在循环中，只需将其放在函数中，然后在self.dictionary行之后的Firebase块内调用该函数即可。尝试一下，如果它不起作用，更新您的文章与更新的代码，我们将制定一个答案。 – Jay
是的！谢谢！这是我需要的正确方向。我创建了一个函数来拆分数据解析并在Firebase块中调用该函数。我也想出了我的for/in循环中导致超出范围错误的错误。在下面发布正确的代码以供其他人从中受益。 – Ben