Swift 3 parsing values from a json file - json

Question

Swift 3 , Xcode8.2.1,
I'm trying to extract specific values from a json file in the project. The name of the file is city.list.json, and the syntax of the json file is as follows:
{"_id":707860,"name":"Hurzuf","country":"UA","coord":{"lon":34.283333,"lat":44.549999}}
{"_id":519188,"name":"Novinki","country":"RU","coord":{"lon":37.666668,"lat":55.683334}}
The input I have is the country name and i need the id value or the country code relevant returned as a string.
I get an error:
"Type 'Any?' has no subscript members",
The method I wrote:
private func findCountryCodeBy(location: String)->String{
var result:String="";
let bundle = Bundle(for: type(of: self));
if let theURL = bundle.url(forResource: "city.list", withExtension: "json") {
do {
let data = try Data(contentsOf: theURL);
if let parsedData = try? JSONSerialization.jsonObject(with: data, options:[]) as! [String:Any] {
result = parsedData["_id"][location][0] as! String;
}
} catch {
print(error);
result = "error";
}
}
return result;
}

Answer 1

That is not valid JSON. I think the nearest valid JSON equivalent would be EITHER a JSON list like:
[
{"_id":707860,"name":"Hurzuf","country":"UA","coord":{"lon":34.283333,"lat":44.549999}},
{"_id":519188,"name":"Novinki","country":"RU","coord":{"lon":37.666668,"lat":55.683334}}
]
Ie, a list enclosed within square brackets with each item separated by a comma.
OR a JSON dictionary:
{
"707860": {"name":"Hurzuf","country":"UA","coord":{"lon":34.283333,"lat":44.549999}},
"519188": {"name":"Novinki","country":"RU","coord":{"lon":37.666668,"lat":55.683334}}
}
Ie, a dictionary enclosed within curly brackets with the key (in this case I've used your _id as the key) before the : and the value (a dictionary of all the other items" after the :.
(Newlines, tabs, whitespace are ignored, I've just included them to make it obvious what I've done).
I think that the dictionary version may suit your code better, but it depends on what else you want to do with the data. A list may suit some situations better.
I wrote a quick Python script to simply read JSON from a file (and not do anything else with it), and it produced a parsing error for the not-quite-JSON that you had, but it worked fine on both of my JSON examples, above.
NB: If you do NOT have control over the format of the file you are reading (ie, if you are receiving it from some other source which cannot produce it in any other format) then you will have to either modify the format of the file after you receiv it to make it valid JSON, OR you will have to use something other than JSONSerialization to read it. You could modify it by replacing all occurrences of }{ or }\n{ with },{ and then put [ at the beginning and ] at the end. That should do the job for converting this particular file to valid JSON for a list. Converting to a dictionary would be a little more involved.
Ideally though, you may have control over the file format yourself, in which case, just change whatever generates the file to produce correct JSON in the first place.
Once you have your valid JSON and parsed it into your parsedData variable, you'll then need to fix this line:
result = parsedData["_id"][location][0] as! String;
Assuming that location is the the equivalent of the _id string in the JSON, then you may be able to use the dictionary version of the JSON above and replace that line with something like:
result = parsedData[location]["country"];
However, if location is not the _id string in the JSON, then you'd be better off using the list version of the JSON above, and use a for loop to compare the values of each list item (or use a dictionary version of the JSON keyed on whatever location actually relates to in the JSON).