We fetch some JSON data using a REST protocol like this.
jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments)
Which looks like this:
jsonResult: (
{
board = "[[\"1:\",\"Y\",\"U\",\"P\"]]";
})
From this we get a game board like so:
if let boardContentArray = jsonResult[0]["board"] as NSArray?{
print("boardContentArray: \(boardContentArray)" )
} else {
print("board element is not an NSArray")
}
The boardContentArray looks like this: It i supposed to be a 2D array with only one row and four columns at the moment, but it should should work for any given size.
[["1:","Y","U","P"]]
How can you retrieve the individual values of boardFromRemote. I imagine to get the element at 0,0 in the 2D array some way like this:
boardContentArray[0][0]
This should then return "1:", which is not the case. This exact syntax is incorrect and won't compile. What is the correct way to retrieve an element from the boardContentArray variable?
The content of jsonResult[0]["board"] is a JSON String which can be decoded as an array with NSJSONSerialization. You have to first transform the String to NSData, then decode it like this for example:
do {
let boardContentArray = "[[\"1:\",\"Y\",\"U\",\"P\"]]" // the String from jsonResult[0]["board"]
if let boardData = boardContentArray.dataUsingEncoding(NSUTF8StringEncoding),
let boardArray = try NSJSONSerialization.JSONObjectWithData(boardData, options: []) as? [[String]] {
print(boardArray[0]) // ["1:", "Y", "U", "P"]
}
} catch let error as NSError {
print(error)
}
Related
I decide some JSON and try to typecast it to a dictionary of String: classy and it fails. I have found that often the reason I have trouble doing something is because of a misunderstanding of how Swift works, so here is what I want to happen. Feel free to tell me that I am doing it wrong and if I do it this way all will be wonderful.
I want my data to live between runs of the app so I have to save the data to storage between runs. I have an object, data and associated code, and I have places where changes I make to a copy should reflect back to the original so it is a class. I have a bunch of these objects and most of the time I pick the one I want based on an id that is an integer. An array is not good since it would be a sparse array cause come ids are not used. I came up with a dictionary with a key of the id and data of the structure. I turned the key from an Int to a String, by changing the Int id to a String, cause converting a dictionary to JSON is MUCH easier for a key that is a string. I save the JSON string. When the app starts again I read the string in and convert the JSON string to Any. Then I typecast the result to the desired dictionary. This is where it fails. The cast does not work. In my Googling the samples I found said this should work.
Here is my code:
class Y: Codable, Hashable {
var a: String = "c"
static func ==(lhs: Y, rhs: Y) -> Bool {
return lhs.a == rhs.a
}
func hash(into hasher: inout Hasher) {
hasher.combine(a)
}
}
struct ContentView: View {
var body: some View {
VStack {
Button ("Error") {
var y = Y()
var yDict = [String: Y]()
yDict["0"] = y
do {
let encodedData = try JSONEncoder().encode(yDict)
let jsonString = String(data: encodedData, encoding: .utf8)
let decoded = try JSONSerialization.jsonObject(with: encodedData, options: [])
if let yyDictDec = decoded as? [String:Y] {
print("yDict after decide")
print (yyDictDec)
}
} catch {
print(error.localizedDescription)
}
print("x")
}
}
}
}
In this code the if yyDictDec = is failing, I think, cause the prints after it never happen. I can cast it as [String, Any] but I really need it to be my class.
My problem is in the convert JSON back to the dictionary. I feel I am missing something fairly simple.
Don´t use JSONSerialization use JsonDecoder and decode it to the the type it was before encoding. e.g.:
let decoded = try JSONDecoder().decode([String: Y].self, from: encodedData)
I have a very large JSON file that I have downloaded from the web, and I need to parse this in Swift. The JSON construction is an array of dictionaries. Each dictionary object contains a key of "phone" (referring to the phone number), and whose value is the actual phone number in the form of a string.
What I would like to do, is iterate through the entire list of dictionary objects in the array, and ensure that there are no dictionary objects that have the same value for the key, "phone". If a duplicate is found, I would like to eliminate it from the list, and print it out to the console.
Here is the relevant code that I have:
guard let json = try? JSONSerialization.jsonObject(with: data) as? [[String: Any]] else {
print("error")
return
}
for dict in json! {
//This is where I would do the check
}
How would I accomplish this?
You can do as
var ph = [String]()
var newjson = [[String:String]]()
for dict in json {
if ph.contains(dict["Phone"]!) {
print("duplicate phone \(dict["Phone"]!)")
} else {
ph.append(dict["Phone"]!)
newjson.append(dict)
}
}
print(newjson)
Hare newjson is the new array of dictionary that do not have duplicate phone
Use the array extension method to remove the duplicates from the json object
extension Array where Element: Equatable {
mutating func removeDuplicates() {
var result = [Element]()
for value in self {
if !result.contains(value) {
result.append(value)
}
}
self = result
}
}
Alamofire.request(apiURL, method: .get, parameters:parameters, headers:headers)
.responseJSON { response in
if let result = response.result.value {
let json = JSON(result)
var listArray = json["somekey"].arrayValue
listArray.removeDuplicates()
print(listArray)
}
}
I am having a problem where I create a dictionary in a method and then try to make a field equal to the dictionary!
So:
var theJson : NSDictionary!
func someMethod()
{
if let theDictionary = valueFromGoogleDirections as? NSDictionary
theJson = theDictionary
}
func fieldTest()
{
print(theJson)
}
after calling someMethod and then fieldTest the fieldTest method always prints "{ }" which I figure means it is an empty dictionary. What is going on? I know that theDictionary is getting values because I am able to use its values from within the someMethod method.
try this:
theJson = theDictionary.copy()
I'm Having trouble with JSON and Swift 2.
I'm getting this Array from the server
[{"KidName":"Jacob","KidId":1,"GardenID":0},
{"KidName":"Sarah","KidId":2,"GardenID":0},
{"KidName":"Odel","KidId":3,"GardenID":0}]
I'm familiar with JSON and I know it's not the recommended way to get a JSON, since it's supposed to be something like
{"someArray":[{"KidName":"Jacob","KidId":1,"gardenID":0}, .....
So my first question is it possible to run over the first JSON I've post and get the KidName number without editing the JSON and Add to it a JSON OBJECT to hold the array ?
my second question is really with Swift 2, how can I get the KidName (after I've edited the JSON to have an holder for the array)?
this is my code... (please read the Notes I've added)
BTW, I'm familiar with SwiftyJSON as well...
// Method I've build to get the JSON from Server, the Data is the JSON
sendGetRequest { (response, data ) -> Void in
// need to convert data to String So I can add it an holder
if let str = NSString(data: data, encoding: NSUTF8StringEncoding) as? String {
/**
after editing the str, i'm Having a valid JSON, let's call it fixedJSON
*/
let fixedJSON = "{\"kidsArray\":\(dropLast)}"
// Now I'm converting it to data back again
let jsonTodata = fixedJSON.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
// After Having the data, I need to convert it to JSON Format
do{
let dataToJson = try NSJSONSerialization.JSONObjectWithData(jsonTodata, options: []) as! [String:AnyObject]
//Here I'm getting the KidID
if let kidID = jsonSe["kidsArray"]![0]["KidId"]!!.integerValue {
print("kidID in first index is: \(kidID)\n")
}
//NOW trying to get the KidName which not working
if let kidname = jsonSe["kidsArray"]![0]["KidName"]!!.stringValue {
print("KidName is \(kidname)\n")
}
}
So as you can see, I'm not able to get the KidName.
Any Help Would be Appreciate.
You can use the following function to get the 'someArray' array and then use this getStringFromJSON function to get the 'KidName' value.
func getArrayFromJSON(data: NSDictionary, key: String) -> NSArray {
if let info = data[key] as? NSArray {
return info
}
else {
return []
}
}
let someArray = self.getArrayFromJSON(YourJSONArray as! NSDictionary, key: "someArray")
func getStringFromJSON(data: NSDictionary, key: String) -> String {
if let info = data[key] as? String {
return info
}
return ""
}
let KidName = self.getStringFromJSON(someArray as! NSDictionary, key: "KidName")
Hope this might be useful to you.
I am trying to parse data which look:
It looks like each record is sequential.. 0, 1, 2 and then within each record there are lots of key value pairs such as the name or showID.
I want to go into each record and only get certain pairs, for example the name, showID and Date.
Here is my code, I am unsure what should be my modal in for item in loop
in other words, how do I get the specific fields into my empty dictionary array?
let task = NSURLSession.sharedSession().dataTaskWithURL(url) { (data, response, error) -> Void in
if let urlContent = data
{
do
{
var jsonResult:NSDictionary = try NSJSONSerialization.JSONObjectWithData(urlContent, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if let items = jsonResult["items"] as! NSArray?
{
var emptyArrayOfDictionary = [[String : AnyObject]]()
for item in 0...jsonResult.count
{
}
}
The idea would be to create a struct (or a class) which contains the properties you need, created with an initializer from the values in your dictionaries.
Let's say you want to make "Show" objects containing the show name and the show ID.
You could create a struct like this:
struct Show {
let name:String
let showID:Int
init?(dictionary: [String:AnyObject]) {
guard let name = dictionary["name"] as? String,
let showID = dictionary["showID"] as? Int else {
return nil
}
self.name = name
self.showID = showID
}
}
Then iterate over your dictionaries and pass each one to the struct initializer, something like this:
let task = NSURLSession.sharedSession().dataTaskWithURL(url) { (data, response, error) -> Void in
if let urlContent = data {
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(urlContent, options: []) as? [String : AnyObject] {
if let items = jsonResult["items"] as? [[String : AnyObject]] {
let shows = items.flatMap { Show(dictionary: $0) }
}
}
} catch {
print(error)
}
}
}
The struct initializer is an Optional one, meaning that if the dictionary does not contain the keys "name" or "showID" it will not create the object and will return nil instead; that's why we're using flatMap to iterate instead of map (because flatMap unwraps the Optionals).
Now you have an array of objects, shows, and you can filter or sort its contents easily with Swift methods like sort, filter, etc.
Each object in the shows array is a Show object and has name and showID properties with the data of your dictionaries.
What flatMap does is create an array of Show objects by iterating (like a loop) over the initial array. On this line:
let shows = items.flatMap { Show(dictionary: $0) }
the $0 represents the current array element. What it means is that for each element in the items array, we take it and create a new Show instance with it, and put the resulting array of objects in the constant shows.
There's also map which is often used, but here the init of our Show struct is an optional init, so it returns an Optional Show, and flatMap knows how to deal with this (it will safely unwrap the optional and ignore the nil ones) where map does not.
If you would like to simplify your son parsing try this Open source https://github.com/SwiftyJSON/SwiftyJSON
With this you access name field of item 0
let userName = json[0]["name"].string