Remove All Items from NSDictionary/Dictionary where value == -1.0 - swift

Question

I am migrating my data from 1 format to another for a large update to one of my iOS apps. This means that when a user updates their application it migrates their data to a new location. This new location has much stricter rules and uses proper practices (basically when I first created the app I was a noob and there are bad practices currently in the database and this new location is for good data only).
I have everything migrating nicely and everything works except I need to do one last thing. The large dictionary that I save to the database (it uses firebase fyi) has -1.0 stored everywhere there should be a nil value (bad, I know). What I need to do is loop through the entire dictionary and remove any key where the value of that key is -1.0.
The Dictionary is of type [AnyHashable : Any] which is what firebase uses.
I have tried this so far.
if let data = dataDictionary as? [AnyHashable : Any] {
let foundItems = data.filter { $0.value as? Double == -1.0 }
print(foundItems)
}
the plan was to then loop through that found items array and remove any key from the data dictionary that contained it.
This is what the data dictionary looks like:
"-KpIdh_TQMG4fyfFgkdt" = {
assignments = {
"-KpIgH6uN19OpcuedYe1" = {
assignmentGoal = "-1";
assignmentName = "Information System Proposal";
assignmentResult = 100;
assignmentWeight = 5;
};
"-KpIgJnFlC6fhgS0NWxF" = {
assignmentGoal = "-1";
assignmentName = "Information System";
assignmentResult = "-1";
assignmentWeight = 35;
};
"-KpIgOGSAwg_VSpDWhWR" = {
assignmentGoal = "-1";
assignmentName = "Process Analysis";
assignmentResult = "-1";
assignmentWeight = 30;
};
"-KpIgPhu_3Zxw36xt3O4" = {
assignmentGoal = "-1";
assignmentName = Labs;
assignmentResult = "-1";
assignmentWeight = 10;
};
"-KpIgQoFEdRnLlMAq2VN" = {
assignmentGoal = "-1";
assignmentName = Exam;
assignmentResult = "-1";
assignmentWeight = 20;
};
};
paperColor = 22;
paperGoal = 95;
paperName = "Systems Analysis";
};
};
semesterCode = 17S2;
semesterGoal = 90;
semesterName = "2017 Semester Two";
};
};
and this is what it should look like
"-KpIdh_TQMG4fyfFgkdt" = {
assignments = {
"-KpIgH6uN19OpcuedYe1" = {
assignmentName = "Information System Proposal";
assignmentResult = 100;
assignmentWeight = 5;
};
"-KpIgJnFlC6fhgS0NWxF" = {
assignmentName = "Information System";
assignmentWeight = 35;
};
"-KpIgOGSAwg_VSpDWhWR" = {
assignmentName = "Process Analysis";
assignmentWeight = 30;
};
"-KpIgPhu_3Zxw36xt3O4" = {
assignmentName = Labs;
assignmentWeight = 10;
};
"-KpIgQoFEdRnLlMAq2VN" = {
assignmentName = Exam;
assignmentWeight = 20;
};
};
paperColor = 22;
paperGoal = 95;
paperName = "Systems Analysis";
};
};
semesterCode = 17S2;
semesterGoal = 90;
semesterName = "2017 Semester Two";
};
};

Answer 1

The solution I have is to map (iterate) over each parent key and assign it's child nodes to a variable child. Then test each child property (assignmentGoal, assignmentName etc) for either "-1" for the string and -1 for the ints. If it's a match, remove that key: value pair from child.
Then assign child back to the parent node.
let result: [Any] = dict.map { dictionary in
var d = dictionary
var child = d.value as Dictionary
if let goal = child["assignmentGoal"] as? String, goal == "-1" {
child.removeValue(forKey: "assignmentGoal")
}
if let name = child["assignmentName"] as? String, name == "-1" {
child.removeValue(forKey: "assignmentName")
}
if let result = child["assignmentResult"] as? Int, result == -1 {
child.removeValue(forKey: "assignmentResult")
}
if let weight = child["assignmentWeight"] as? Int, weight == -1 {
child.removeValue(forKey: "assignmentWeight")
}
d.value = child
return d
}
//show the output
for item in result {
print(item)
}
and the result output
(key: "-KpIgOGSAwg_VSpDWhWR",
value: ["assignmentName": "Process Analysis System", "assignmentWeight": 30])
(key: "-KpIgQoFEdRnLlMAq2VN",
value: ["assignmentName": "Exam", "assignmentWeight": 20])
(key: "-KpIgJnFlC6fhgS0NWxF",
value: ["assignmentName": "Information System", "assignmentGoal": "3", "assignmentWeight": 35])
(key: "-KpIgPhu_3Zxw36xt3O4",
value: ["assignmentName": "Labs", "assignmentWeight": 10])
(key: "-KpIgH6uN19OpcuedYe1",
value: ["assignmentName": "Information System Proposal", "assignmentResult": 100, "assignmentWeight": 5])