我正在使用 Firebase,直到最近才按字母顺序获取数据时没有遇到任何问题。我从来没有使用过查询,我总是只使用数据快照并对其进行一一排序。最近,数据并不总是按字母顺序排列snapVal。如何才能获得按字母顺序排序的数据 snapVal,就像数据库快照中的那样?
真实示例:有 4 条消息,id1-id4(按此顺序)。它们包含消息“1”-“4”。快照看起来是正确的。但是snapVal(snapshot.value)看起来像这样:
["id2": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 2;
TIME = "8:12 PM";
}, "id4": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 4;
TIME = "8:12 PM";
}, "id1": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 1;
TIME = "8:12 PM";
}, "id3": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 3;
TIME = "8:12 PM";
}]
快照是什么样子的:
["id1": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 1;
TIME = "8:12 PM";
}, "id2": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 2;
TIME = "8:12 PM";
}, "id3": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 3;
TIME = "8:12 PM";
}, "id4": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 4;
TIME = "8:12 PM";
}]
为了获取 snapVal,我使用这个:
if let snapVal = snapshot.value as? [String: AnyObject] {
// Comes out of order..
}
澄清:
快照(最终结果是正确的):
Snap (CHAT) {
id1 = {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 1;
TIME = "8:12 PM";
};
id2 = {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 2;
TIME = "8:12 PM";
};
id3 = {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 3;
TIME = "8:12 PM";
};
id4 = {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 4;
TIME = "8:12 PM";
};
}
这是输出print(snapVal.keys)
inside if let snapVal = snapshot.value as? [String: AnyObject]
:
LazyMapCollection<Dictionary<String, AnyObject>, String>(_base: ["id2": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 2;
TIME = "8:12 PM";
}, "id4": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 4;
TIME = "8:12 PM";
}, "id1": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 1;
TIME = "8:12 PM";
}, "id3": {
DATE = "10/20/16";
"FIRST_NAME" = first;
ID = userID;
"LAST_NAME" = last;
MESSAGE = 3;
TIME = "8:12 PM";
}], _transform: (Function))
My Code:
self.firebase.child("Chats").child(chatID).queryOrderedByKey().observeSingleEvent(of: .value, with: { (snapshot) in
print(snapshot)
if let snapVal = snapshot.value as? [String: AnyObject] {
print(snapVal)
for c in snapVal {
print("checking Message as child")
let message = c.value["MESSAGE"] as? String
let fn = c.value["FIRST_NAME"] as? String
let ln = c.value["LAST_NAME"] as? String
let USER_ID = c.value["ID"] as? String
if let userID = USER_ID {
if let msg = message {
if let firstName = fn {
if let lastName = ln {
let username = "\(firstName) \(lastName)"
self.addMessage(userID, text: msg, name: username)
print("Message added! \nMessage Info:")
print("User ID: \(userID)")
print("text: \(msg)")
print("Username: \(username)")
} else {
print("LN did not pass")
}
} else {
print("FN did not pass")
}
} else {
print("Msg did not pass")
}
} else {
print("User ID did not pass")
}
}
}
})