How do I search a very very large json file? - ios

Question

I have a enormous json file and I am trying to extract information form the file, but it is way to big to track down the path. Could I filter it using the id? JSON code I need to pick up course names i.e.
let urlString = "Can't provide the url"
if let url = NSURL(string: urlString){
if let data = try? NSData(contentsOfURL: url, options: []){
let json = JSON(data: data)
parseJSON(json)
}
}
}
func parseJSON(json: JSON){
for (index: String, subJson: JSON) in json {
}
}

Answer 1

I came up with a depth-first way of finding a given JSON object based on a predicate.
I made it into an extension:
extension JSON {
func find(#noescape predicate: JSON -> Bool) -> JSON? {
if predicate(self) {
return self
}
else {
if let subJSON = (dictionary?.map { $0.1 } ?? array) {
for json in subJSON {
if let foundJSON = json.find(predicate) {
return foundJSON
}
}
}
}
return nil
}
}
For instance, to search for the JSON object with a given id field, such as in the question, you can use the method as such:
let json = JSON(data: data)
let predicate = {
(json: JSON) -> Bool in
if let jsonID = json["id"].string where jsonID == "plnMain_ddlClasses" {
return true
}
return false
}
let foundJSON = json.find(predicate)
In this case, if you need to continue and find the classes you were looking for, you would want:
let classes = foundJSON?["children"].arrayValue.map {
$0["html"].stringValue
}
UPDATE — FIND ALL
func findAll(#noescape predicate predicate: JSON -> Bool) -> [JSON] {
var json: [JSON] = []
if predicate(self) {
json.append(self)
}
if let subJSON = (dictionary?.map{ $0.1 } ?? array) {
// Not using `flatMap` to keep the #noescape attribute
for object in subJSON {
json += object.findAll(predicate: predicate)
}
}
return json
}