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.
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 am fairly new to parsing json data and I am attempting to parse some json data from an rss feed generator and I am running into a problem where I can successfully print the data I am getting but I can't save the data to an object.
I have looked through tutorials that used decodables/codables mostly but I was able to use the urlSession and jsonSerialization objects for what I needed just fine.
class JSONSongs {
// initialize song array...
var songArray: [Song] = []
func getSongs() {
let jsonSongUrl = "https://rss.itunes.apple.com/api/v1/us/apple-music/top-songs/all/50/explicit.json"
let songUrl = URL(string: jsonSongUrl) // convert string to usable url
// start url session task with apple music api url...
// we get some data(hopefully), a response code and an error(hoepfully not)
let songTask = URLSession.shared.dataTask(with: songUrl!) { (data, response, error) in
// checking for an error
if error != nil {
print(Error.self)
print(error?.localizedDescription)
return
} else {
// lets store our data in a variable
if let content = data {
do {
// taking the json data and converting it so we can make objects
let json = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)
//print(json) // making sure data is present
// checking to see if our json data is there
guard let jsonOne = json as? [String: Any] else {
print("invalid operation!")
return
}
// accessing top root of the json file
if let feed = jsonOne["feed"] as? [String: Any] {
//print("it worked") // testing
// accessing the results array where the albums are stored
// there are arrays in the nested json data so we need the double brackets to access them
if let result = feed["results"] as? [[String: Any]]{
for item in result {
// attempting to store data in Song object, this is where problems appear
if let songName = (item["name"] as AnyObject? as? String),
let artistName = (item["artistName"] as AnyObject? as? String),
let coverArt = (item["artworkUrl100"] as AnyObject? as? String),
let artistPage = (item["artistUrl"] as AnyObject? as? String) {
self.songArray.append(Song(songName: songName, artistName: artistName, coverArt: coverArt, artistPage: artistPage))
// printing the data to the console works here but I can't save the data to an object
}
}
}
}
} catch {
print(error.localizedDescription)
print(Error.self)
return
}
}
}
}
songTask.resume()
}
}
All I get is either nil when I try and print a string value or 0 when I try and count the number of objects that are present in the songArray array
Basically your code is correct and should work, however this is a version using Decodable.
The songs property will contain the song data
struct Root : Decodable {
let feed : Feed
}
struct Feed : Decodable {
let results : [Song]
}
struct Song : Decodable {
let name, artistName : String
let artworkUrl100, artistUrl : URL
}
class JSONSongs {
var songs = [Song]()
func getSongs() {
let jsonSongUrl = "https://rss.itunes.apple.com/api/v1/us/apple-music/top-songs/all/50/explicit.json"
let songUrl = URL(string: jsonSongUrl) // convert string to usable url
// start url session task with apple music api url...
// we get some data(hopefully), a response code and an error(hoepfully not)
let songTask = URLSession.shared.dataTask(with: songUrl!) { [weak self] data, _, error in
// checking for an error
if let error = error { print(error); return }
do {
// taking the json data and converting it so we can make objects
let result = try JSONDecoder().decode(Root.self, from: data!)
self?.songs = result.feed.results
print(self?.songs)
} catch {
print(error)
}
}
songTask.resume()
}
}
I am using Xcode 9.2 and Swift 4. How can I check if the returned json data is null?
Now it gives me error Type 'Any' has no subscript members at line if json[0]["data"]
var json: NSMutableArray = []
var newsArray: NSMutableArray = []
let url = URLFactory()
var data = try! NSData(contentsOf: url.getURL()) as Data
do {
json = try JSONSerialization.jsonObject(with: data, options: []) as! NSMutableArray
if json[0]["data"] {
// data is not null
}
} catch let error as NSError {
// handle error
}
My JSON returns something like this:
{
"data":
[
{
"news_id":123,
"title":"title",
"news_date":"2017-02-08 21:46:06",
"news_url":"url",
"short_description":"description",
"category_id":4,
"category_name":"Health",
"latlng":
[
{
"lat":"43.003429",
"lng":"-78.696335"
}
]
}
{ ....
}
If you're using Swift 4, I might suggest JSONDecoder:
First, define the types to hold the parsed data:
struct ResponseObject: Codable {
let data: [NewsItem]
}
struct NewsItem: Codable {
let newsId: Int
let title: String
let newsDate: Date
let newsURL: URL
let shortDescription: String
let categoryID: Int
let categoryName: String
let coordinates: [Coordinate]
// because your json keys don't follow normal Swift naming convention, use CodingKeys to map these property names to JSON keys
enum CodingKeys: String, CodingKey {
case newsId = "news_id"
case title
case newsDate = "news_date"
case newsURL = "news_url"
case shortDescription = "short_description"
case categoryID = "category_id"
case categoryName = "category_name"
case coordinates = "latlng"
}
}
struct Coordinate: Codable {
let lat: String
let lng: String
}
And then you can parse it:
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .formatted(formatter)
do {
let responseObject = try decoder.decode(ResponseObject.self, from: data)
print(responseObject.data)
} catch {
print(error)
}
Clearly, if your JSON is different, you might need to change your objects accordingly (e.g. it struck me odd that latlng was an array of coordinates). Also, you can define custom init(from:) methods if you want to convert some of these strings into numbers, but I'd rather fix the JSON, instead (why are latlng returning string values rather than numeric values).
For more information, see Encoding and Decoding Custom Types.
As an aside, I'd advise against this pattern (note, this is your network request logic, but excised of NSData):
let data = try! Data(contentsOf: url.getURL())
That will retrieve the data synchronously, which can be problematic because
the app will be frozen while the data is being retrieved resulting in a poor UX;
you risk having your app killed by the watchdog process which looks for frozen apps; and
you don't have robust error handling and this will crash if the network request fails.
I'd suggest using URLSession:
let task = URLSession.shared.dataTask(with: url.getURL()) { data, _, error in
guard let data = data, error == nil else {
print(error ?? "Unknown error")
return
}
// now parse `data` like shown above
// if you then need to update UI or model objects, dispatch that back
// to the main queue:
DispatchQueue.main.async {
// use `responseObject.data` to update model objects and/or UI here
}
}
task.resume()
I googled a lot, pretty much copied code i found online from tutorials to simply parse a json String in Swift to useable objects.
Code:
func parseJson(json: String) -> [AnyObject] {
let data = json.dataUsingEncoding(NSUTF8StringEncoding)
do {
if let array = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as? [AnyObject] {
return array
}
}
catch {
// Error hanndling here
}
return [AnyObject]()
}
Json String im trying to parse:
"response":{"loggedIn":false,"message":"Some errormessage here"}}
What happens:
The program won't jump into the if let array = ... It stops there since it can't parse the string to json (or AnyObject) and will simply go to return AnyObject.
Why does this happen and how do i fix it?
Adjust your code a little to allow for better debugging:
func parseJson(json: String) -> [AnyObject] {
let data = json.dataUsingEncoding(NSUTF8StringEncoding)
do {
let parsed = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
if let array = parsed as? [AnyObject] {
return array
}
}
catch {
print(error)
}
return [AnyObject]()
}
Two changes there:
Printing any error caught.
Doing JSONObjectWithData and the as? conversion in two separate steps.
Pasting this in a playground quickly reveals an error being caught: "JSON text did not start with array or object and option to allow fragments not set." Your JSON fragment is missing the opening {.
Once that problem is fixed, you’ll see that parsed gets set, but the subsequent if let array = parsed as? [AnyObject] falls through. That’s because your top-level element is a dictionary, not an array, so casting to [AnyObject] fails.
I'm new to Swift - trying to read a JSON file from a URL. My attempt below.
The JSON looks valid - I tested it with JSONLint but it keeps crashing.
Thoughts?
func getRemoteJsonFile() -> NSDictionary {
//Create a new url
let remoteUrl:NSURL? = NSURL(string: "http://nfl-api.azurewebsites.net/myplayers.json")
//check if its nil
if let actualRemoteUrl = remoteUrl {
//try to get the data
let filedata:NSData? = NSData(contentsOfURL: actualRemoteUrl)
//check if its nil
if let actualFileData = filedata {
//parse out the dictionaries
let jsonDict = NSJSONSerialization.JSONObjectWithData(actualFileData, options: NSJSONReadingOptions.AllowFragments, error: nil) as NSDictionary
return jsonDict
}
}
return NSDictionary()
}
This took me a second to figure out, so I don't blame you for missing it.
The JSON you linked to is minified, so it's difficult to see the structure. Let's take a look at (a fragment of) it after piping it through a prettifier:
[
{
"PlayerId":2501863,
"PlayerName":"Peyton Manning",
"PlayerTeam":"DEN",
"PlayerPosition":"QB",
"PlayerPassingYards":4727,
"PlayerPassingTDs":39,
"PlayerInterceptions":15,
"PlayerRushingYards":-24,
"PlayerRushingTDs":0,
"PlayerReceivingYards":0,
"PlayerReceivingTDs":0,
"PlayerReturnYards":0,
"PlayerReturnTDs":0,
"PlayerFumbleTDs":0,
"PlayerTwoPointConversions":2,
"PlayerFumblesLost":2,
"PlayerTeamLogo":"http://i.nflcdn.com/static/site/7.0/img/logos/teams-gloss-81x54/den.png"
}
]
Huh. It's encased in brackets, which means that it's an array.
It's an array, so you can't cast it as an NSDictionary. Instead, you could cast it as an NSArray, but why not use native Swift types?
Well, if you don't like types, you're about to find out, but I still think that this is a better way, because it forces you to think about the data you're parsing.
So we have the first part of our type definition for this function; it's an array ([]). What components is our array made up of? We could go with a simple NSDictionary, but we're doing full native types here, so let's use a native Swift dictionary.
To do that, we have to know the types of the dictionary (the syntax for a native dictionary type is [KeyType: ValueType]). Examining the JSON shows that all of the keys are Strings, but the values are of varying types, so we can use AnyObject.
That gives us a dictionary type of [String: AnyObject], and our entire JSON is an array of that, so the final type is [[String: AnyObject]] (wow).
Now that we have the proper type, we can modify the function you're using to parse the JSON a bit.
First of all, let's use our new type for the return and cast values. Then, let's make the return type optional in case something goes wrong and add an error variable to document that.
A cleaned up function would look something like this:
func getData() -> [[String: AnyObject]]? {
let data: NSData? = NSData(contentsOfURL: NSURL(string: "http://nfl-api.azurewebsites.net/myplayers.json")!)
if let req: NSData = data {
var error: NSError?
if let JSON: [[String: AnyObject]] = NSJSONSerialization.JSONObjectWithData(req, options: NSJSONReadingOptions.AllowFragments, error: &error) as? [[String: AnyObject]] {
return JSON
}
}
return nil
}
That's it!
We can now call the function and extract values from our [[String: AnyObject]] (again, wow) like this:
if let data: [[String: AnyObject]] = getData() {
println(data[0]["PlayerName"]!) // Peyton Manning
}
Update your code with this:
func getRemoteJsonFile() -> [NSDictionary] {
// Create a new URL
let remoteUrl:NSURL? = NSURL(string: "http://nfl-api.azurewebsites.net/myplayers.json")
let urlString:String = "\(remoteUrl)"
// Check if it's nil
if let actualRemoteUrl = remoteUrl {
// Try to get the data
let fileData:NSData? = NSData(contentsOfURL: actualRemoteUrl)
// Check if it's nil
if let actualFileData = fileData {
// Parse out the dictionaries
let arrayOfDictionaries:[NSDictionary]? = NSJSONSerialization.JSONObjectWithData(actualFileData, options: NSJSONReadingOptions.MutableContainers, error: nil) as [NSDictionary]?
if let actualArrayOfDictionaries = arrayOfDictionaries {
// Successfully parsed out array of dictionaries
return actualArrayOfDictionaries
}
}
}
return [NSDictionary]()
}
This is working fine for me.