ios - Swift 4 / Firebase - 从不同数组中的实时数据库读取和存储双嵌套项
问题描述
我真的很纠结如何从 firebase 实时数据库中读取和存储我的数据。这是我的数据库的样子:
text json
{
"Live": {
"Today": {
"121321": {
"title": "rnd",
"description": "blah blah blah",
"stamp": 1111
},
"121441": {
"title": "arnd",
"description": "blh blah blah",
"stamp": 134
}
},
"Tomorrow": {
"143821": {
"title": "brnd",
"description": "blh blah blah",
"stamp": 1134
}
},
"ThisWeek": {
"18934": {
"title": "drnd",
"description": "blh blh blah blah blah",
"stamp": 237812
},
"323123": {
"title": "crnd",
"description": "blh blh blah blah",
"stamp": 138921
}
}
}
}
我用绿色突出显示了我所说的事件。事件有标题、描述和标记。然后我有一个今天、明天和本周的外巢。今天、明天和本周是各自独立的字典,包含任意数量的事件。
我在一个单独的 swift 文件中创建了一个类:
class Event: NSObject {
var EventTitle: String?
var EventDescription: String?
var EventStamp: Int?
}
我想要三个数组。第一个数组包含“今天”的所有事件,第二个数组包含“明天”的所有事件,第三个数组包含“本周”的所有事件。我最终需要通过标记对每个数组中的事件进行排序。但是,我被困在如何将 firebase 数据快照转换为事件,然后将所有事件放入数组中。到目前为止我的代码
//declaring empty arrays to fill later
var todayEvents = [Event]()
var tomorrowEvents = [Event]()
var thisweekEvents = [Event]()
//Getting snapshots
ref?.child(".../LiveEvents").observeSingleEvent(of: .value, with: { (snapshot) in
let todaysnap = snapshot.childSnapshot(forPath: "Today")
let tomorrowsnap = snapshot.childSnapshot(forPath: "Tomorrow")
let thisweeksnap = snapshot.childSnapshot(forPath: "ThisWeek")
//need to assign data to events and to arrays Today, Tomorrow, Thisweek
})
当我尝试打印我的快照数据时,我得到一个可选值,如果我尝试使用字符串分配变量,那么我会得到一个错误,如“无法将'DataSnapshot'类型的值转换为强制类型'Int'”。我看过其他答案,但我相信我的情况有所不同,因为我有双重嵌套数据并且我想分配给不同的数组。我正在使用 swift 4
谢谢
---如果我打印(今天快照)我得到
Snap (Today) {
121321 = {
title = rnd;
description = blah blah blah;
stamp = 1111
};
121441 = {
title = arnd;
description = blh blah blah;
stamp = 134
};
做 print(todaysnap.value) 给了我同样的东西,除了类型是“可选”而不是“快照(今天)”
解决方案
这是读取 Live 节点中所有数据的完整代码,并将 Today、Tomorrow 和 ThisWeek 事件放入单独的数组中
var todayArray = [String]()
var tomorrowArray = [String]()
var thisWeekArray = [String]()
let liveRef = self.ref.child("Live")
liveRef.observeSingleEvent(of: .value, with: { snapshot in
let todaySnap = snapshot.childSnapshot(forPath: "Today")
for todayChild in todaySnap.children {
let todayChildSnap = todayChild as! DataSnapshot
let todayDict = todayChildSnap.value as! [String: Any]
let title = todayDict["title"] as! String
todayArray.append(title)
}
let tomorrowSnap = snapshot.childSnapshot(forPath: "Tomorrow")
for tomorrowChild in tomorrowSnap.children {
let tomorrowChildSnap = tomorrowChild as! DataSnapshot
let tomorrowDict = tomorrowChildSnap.value as! [String: Any]
let title = tomorrowDict["title"] as! String
tomorrowArray.append(title)
}
let thisWeekSnap = snapshot.childSnapshot(forPath: "ThisWeek")
for thisWeekChild in thisWeekSnap.children {
let thisWeekChildSnap = thisWeekChild as! DataSnapshot
let thisWeekDict = thisWeekChildSnap.value as! [String: Any]
let title = thisWeekDict["title"] as! String
thisWeekArray.append(title)
}
print("Today")
for today in todayArray {
print(" " + today)
}
print("Tomorrow")
for tomorrow in tomorrowArray {
print(" " + tomorrow)
}
print("This Week")
thisWeekArray.map { print(" " + $0) } //gettin' all swifty here
})
输出是
Today
rnd
arnd
Tomorrow
brnd
This Week
drnd
crnd
但是......我可能会改变结构:
Live
event_0 //generated with childByAutoId
title: "rnd"
timestamp: "20180918"
event_1
title: "brnd"
timestamp: "20180919"
因为您现在可以查询每个节点,提取今天的事件。明天的活动或本周活动或您喜欢的任何一天或范围。
我将每天上传新数据,所以今天、明天和本周将每天刷新
使用这种结构,您需要做的就是添加节点,您的查询将找出哪些节点在什么时间段内是什么。
由于您的 Event 类不做任何处理,本质上只是一个保存数据的结构,那么结构怎么样:
struct EventStruct {
var EventTitle: String?
var EventDescription: String?
var EventStamp: Int?
}
然后将事件添加到数组中:
let title = thisWeekDict["title"] as! String
let desc = thisWeekDict["desc"] as! String
let stamp = thsWeekDict["stamp"] as! String
let anEvent = Event(title: title, desc: desc, stamp: stamp)
thisWeekArray.append(anEvent)
或将其保留为一个类,然后将快照传入并让该类从快照中分配属性。无论哪种方式,请为 nil 添加错误检查。
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