Been working on pulling data from an API, finally got that to work (I believe correctly) but when I print out variables within the dictionary, "Optional" gets added to the string
do {
let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers) as? NSDictionary
print(jsonResult)
if (jsonResult != nil) {
if let players = jsonResult?["players"] as? [Dictionary<String, AnyObject>] {
for player in players {
let personID = player["name"]
print(personID)
}
}
} else {
print("No Data")
// couldn't load JSON, look at error
}
}
Sample of the JSON Output:(note I cut this down and used only the first element)
Optional({
players = (
{
name = "Derek Anderson";
},
Print statement:
Optional(Derek Anderson)
My assumption here is that its printing the Optional Dictionary and then grabbing the "players" name. Meaning I haven't pulled just that name out. I've pulled the name out of the players array, not the Optional.
I feel like I may be adding that Optional Array in some way though, cant seem to figure this one out!
Solved, the variable needs to be unwrapped:
do {
let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers) as? NSDictionary
print(jsonResult)
if (jsonResult != nil) {
if let players = jsonResult?["players"] as? [Dictionary<String, AnyObject>] {
for player in players {
let personID = player["name"]!
print(personID)
}
}
} else {
print("No Data")
// couldn't load JSON, look at error
}
}
Related
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 trying to read the data for "Name" in a JSON file I am hosting using Swift and I seem to only be able to read the whole JSON file and not able to pick out specific data. My JSON file contains this:
[{"Email":"Admin#admin.com","Password":"password","Name":"Admin"}]
The swift code I am using is this:
override func viewDidLoad() {
super.viewDidLoad()
//to get data from external DB
let url = URL(string: "http://localhost/Projects/Test_mobileAPI/test_userInfo.php?email=Admin#admin.com")
let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in
if error != nil{
print("Error Occured")
}
else{
print("Okie")
if let content = data {
do{
//Array
let myJson = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as AnyObject
print("this part works")
print(myJson)
if let diction = myJson as? NSDictionary
{
if let name = myJson["Name"]{
print(name as Any)
}
}
}
catch{
print(error)
}
}
}
}
task.resume()
}
The output I keep getting is this:
Okie
this part works
(
{
Email = "Admin#admin.com";
Name = Admin;
Password = password;
}
)
But I do not get just the value for "Name". Can anyone help me get the value for "Name" (i.e "Admin")
Can you try
if let myJson = try JSONSerialization.jsonObject(with: content) as? [[String:Any]] {
if let first = myJson.first {
print(first["Name"])
}
}
The problem is that the JSON that you're receiving back isn't a Dictionary, it's a single element array with a dictionary in it. So when you do
if let diction = myJson as? NSDictionary
the myJson object is failing the cast to NSDictionary. If you unwrap the array first, you should then be able to reference the dictionary and pick off any keyed values you want:
if let array = myJson as? NSArray
{
if let myDict = array[0] as? NSDictionary
{
if let name = myDict ["Name"]{
print(name as Any)
}
}
}
I am brand new to using JSON and wanted to get started with a simple app to provide a movie overview when you type in a title. My below code returns everything in one big string. How do I get just one piece of information like the overview or year?
With my below attempt, print(obj["overview"] as Any)) prints "nil" and print(obj) looks like this:
{
page = 1;
results = (
{
adult = 0;
"backdrop_path" = "/A0aGxrCGRBuCrDltGYiKGeAUect.jpg";
"genre_ids" = (
53,
80
);
id = 680;
"original_language" = en;
"original_title" = "Pulp Fiction";
overview = "A burger-loving hit man, his philosophical partner, a drug-addled gangster's moll and a washed-up boxer converge in this sprawling, comedic crime caper. Their adventures unfurl in three stories that ingeniously trip back and forth in time.";
Current Code:
let query = "Pulp+Fiction"
let urlString = "https://api.themoviedb.org/3/search/movie?api_key={MYAPIKEY}&query=\(query)"
let url = URL(string: urlString)
URLSession.shared.dataTask(with:url!) { (data, response, error) in
if error != nil {
print(error as Any)
} else {
do {
let parsedData = try JSONSerialization.jsonObject(with: data!) as Any
if let obj = parsedData as? NSDictionary {
print(obj["overview"] as Any)
print(obj)
}
} catch {
print("error")
} }
}.resume()
}
// write this extension anywhere in your any swift file
extension String{
func toDictionary() -> NSDictionary {
let blankDict : NSDictionary = [:]
if let data = self.data(using: .utf8) {
do {
return try JSONSerialization.jsonObject(with: data, options: []) as! NSDictionary
} catch {
print(error.localizedDescription)
}
}
return blankDict
}
}
//now in your code modify as
if data != nil {
let responseString = String(data: data!, encoding: .utf8)!
if(responseString != "")
{
//convert response string into dictionary using extended method
let responseValues = responseString.toDictionary()
//access value using keyPath using
let value = responseValues.value(forKeyPath: "key.key2")
//where key2 is the target key which is inside the value of key
}
}
First of all JSON results are never Any. As already mentioned in the comments the root object is a dictionary
if let parsedData = try JSONSerialization.jsonObject(with: data!) as? [String:Any],
The key overview is in array for key results
let results = parsedData["results"] as? [[String:Any]] {
You have to iterate over the array to get the values for key overview
for result in results {
print(result["overview"] as? String ?? "no value for key overview")
}
}
It's highly recommended to use the Codable protocol and custom structs in Swift 4.
I am trying to parse my JSON data and append only those objects into array which meets specified condition. At the moment I have commented out code which fetch all objects from the API and add them into array. However, I would like to limit it so that it only appends objects with "wger.de" value for "license_author" key.
However I am getting error on line:
if eachExercise["license_author"] == "wger.de"
Binary operator '==' cannot be applied to operands of type 'Any?' and 'String'.
However I still wants to keep it as Any object because I would like to fetch both strings and integers data from my API.
This is the code for my parseData() function:
func parseData() {
fetchedExercise = []
let urlPath = "https://wger.de/api/v2/exercise/?format=json&language=2&status=2"
let url = URL(string: urlPath)!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if error != nil {
print("Error while parsing JSON")
}
else {
do {
if let data = data,
let fetchedData = try JSONSerialization.jsonObject(with: data, options: .mutableLeaves) as? [String:Any],
let exercises = fetchedData["results"] as? [[String: Any]] {
// WORKING CODE
/*
for eachExercise in exercises
{
let name = eachExercise["name"] as! String
let description = eachExercise["description"] as! String
self.fetchedExercise.append(Exercise(name: name, description: description))
}
*/
// TESTING
for eachExercise in exercises {
if eachExercise["license_author"] == "wger.de" {
let name = eachExercise["name"] as! String
let description = eachExercise["description"] as! String
let id = eachExercise["id"] as! Int
self.fetchedExercise.append(Exercise(name: name, description: description))
}
}
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}
catch {
print("Error while parsing data.")
}
}
}
task.resume()
}
Use the where clause and optional downcast Any to String
for eachExercise in exercises where eachExercise["license_author"] as? String == "wger.de" { ...
You need cast it to String.
if eachExercise["license_author"] as? String == "wger.de" {
}
I have the following swift3 code. The JSON can return a NSNull value for the $0[2] value.
struct Player3 {
let name : String
var score : String
let avatar : String
}
class HistoricLeagueVC: UITableViewController {
var players = [Player3]()
override func viewDidLoad() {
super.viewDidLoad()
let urlString = "https://str8red.com/jsonoverallleaderboard/1025/"
let url = URL(string: urlString)
URLSession.shared.dataTask(with:url!) { (data, response, error) in
if error != nil {
print("there was an error")
} else {
do {
let parsedData = try JSONSerialization.jsonObject(with: data!) as! [[String]]
self.players = parsedData.map { Player3(name: $0[0], score: $0[1], avatar: $0[2]) }
print(self.players.count)
DispatchQueue.main.async {
self.tableView.reloadData()
}
} catch let error as NSError {
print(error)
}
}
}.resume()
}
I have tried to convert it to an empty string without success. I have also tried to set a default string such as "https://str8red.com/static/no_profile_picture.png" which ideally is what I would like to do.
The error in the terminal states Could not cast value of type 'NSNull' (0xed1c78) to 'NSString' (0x57b6b8).
Any help would be appreciated.
Do not cast to [[String]] then:
let parsedData = try JSONSerialization.jsonObject(with: data!) as! [[Any]]
self.players = parsedData.map { Player3(
name: ($0[0] as? String) ?? "",
score: ($0[1] as? String) ?? "",
avatar: $0[2] as? String, // keeping `nil` here
)}
You should probably even as! [[Any]] do in a safer manner (using as?) but the above will work.
Your code will crash brutally if anything goes wrong with your input data. Ask your boss if he or she is Ok with that. I wouldn't. Here's how you will crash: If data == nil (but it shouldn't be if error == nil). You catch the problem that data cannot be parsed without crashing. You crash if data doesn't parse to an array, you crash if the elements of the array are not all arrays, you crash if the elements inside the inner arrays are not all Strings, and you crash if any of the inner arrays contain two or fewer strings. I'd say that is pretty unacceptable.
My strategy would be: If the response cannot be parsed or is not an array of arrays, then ignore it, leaving self.players unchanged. If there is an array of arrays, reset self.players, then add a player for each array that contains at least three items, of which the first two must be strings.
guard data != nil else { return }
guard let parsed = try? NSJSONSerialization(with: data!) else { return }
guard let arrays = parsed as? [[Any]] else { return }
self.players.removeAll()
for array in arrays {
guard array.count >= 3,
let name = array [0] as? String,
let score = array [1] as? String else { continue }
let avatar = array [2] as? String ?? ""
self.players.append(Player3 (name: name, score: score, avatar: avatar))
}
It's a good idea to move something like this into a separate method. Add whatever error handling or logging you feel is appropriate.