I am trying to loop through a JSON array which I am getting from an HTTP Request, but I am not sure how.
What I have tried is this:
var request = NSMutableURLRequest(url: url! as URL, cachePolicy: NSURLRequest.CachePolicy.returnCacheDataElseLoad, timeoutInterval: Double.infinity)
if Reachability.isConnectedToNetwork(){
request = NSMutableURLRequest(url: url! as URL, cachePolicy: NSURLRequest.CachePolicy.useProtocolCachePolicy, timeoutInterval: Double.infinity);
}
let session = URLSession.shared
var getResp = false
var zinnen : [Zin] = []
let task = session.dataTask(with: request as URLRequest,
completionHandler: { data, response, error -> Void in
let json = try? JSONSerialization.jsonObject(with: data!, options: []) as? [String: Any]
for case let data in json {
if let zin = Zin(json: data) {
zinnen.append(zin)
}
}
})
task.resume()
And this is my struct:
struct Zin : CustomStringConvertible {
var description: String
let id : Int
let dutch_sentence : String
let polish_sentence : String
init(dictionary: [String: Any]) {
self.id = dictionary["id"] as? Int ?? 0
self.dutch_sentence = dictionary["dutch_sentence"] as? String ?? ""
self.polish_sentence = dictionary["polish_sentence"] as? String ?? ""
}
}
A sample of the JSON Array:
[
{
"id":"35",
"dutch_sentence":"Ja",
"polish_sentence":"Tak"
},
{
"id":"36",
"dutch_sentence":"Nee",
"polish_sentence":"Nie"
}
]
But in this I get the error
Type '[String: Any]??' does not conform to protocol 'Sequence'
Don't ignore the error! Both try? and optional downcast cause a nested optional (Optional<Optional<[String:Any]>>) which of course is not a sequence, not even when being casted to an array.
Handle the error, optional bind the result and cast the result to the more specified array [[String:String]]. According to the JSON the value for id is String not Int.
do {
if let json = try JSONSerialization.jsonObject(with: data!) as? [[String: String]] {
for zinData in json {
let zin = Zin(dictionary: zinData)
zinnen.append(zin)
}
}
} catch { print(error) }
PS: The initializer in the Zin class does not match the initializer in the parsing code. I'm using the version of the class. You have to change the type of id from Int to String
Related
i have the following Json
USD {
"avg_12h" = "8252.96";
"avg_1h" = "8420.80";
"avg_24h" = "8253.11";
"avg_6h" = "8250.76";
rates = {
last = "8635.50";
};
"volume_btc" = "76.05988903";
}
where USD is a key found after searching in a json file, i want to access "avg_12h" value and assign it to a variable, what is the best way to do it.
import UIKit
/*URLSessionConfiguration.default
URLSessionConfiguration.ephemeral
URLSessionConfiguration.background(withIdentifier: <#T##String#>)
// create a URLSession instance
let config = URLSessionConfiguration.default
let session = URLSession(configuration: config)*/
/*create a URLSession instance*/
let config = URLSessionConfiguration.default
let session = URLSession(configuration: config)
/*
The session.dataTask(with: url) method will perform a GET request to the url specified and its completion block
({ data, response, error in }) will be executed once response is received from the server.*/
let url = URL(string: "https://localbitcoins.com/bitcoinaverage/ticker-all-currencies")!
let task = session.dataTask(with: url) { data, response, error in
// ensure there is no error for this HTTP response
guard error == nil else {
print ("error: \(error!)")
return
}
// ensure there is data returned from this HTTP response
guard let content = data else {
print("No data")
return
}
/*JSONSerialization.jsonObject(with: content,
options: JSONSerialization.ReadingOptions.mutableContainers) as?
[String: Any] will parse the JSON data returned from web server into a dictionary*/
// serialise the data / NSData object into Dictionary [String : Any]
guard let json = (try? JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [String: Any] else {
print("Not containing JSON")
return
}
let bolivares = "VES"
for (key, value) in json {
if key==bolivares {
print(value)
//ADD CODE TO ACCESS avg_12h and assign it to a value
}
}
}
// update UI using the response here
// execute the HTTP request
task.resume()
Assuming you are receiving the JSON as raw data and it hasn't been converted to an object yet, ou would want to do something like the following:
guard let jsonObject = try? JSONSerialization.jsonObject(with: data, options: []) as! [String:[String]] else { return }
let usd = jsonObject["USD"]
let avg_12h = usd["avg_12h"]
But this will only work based on some assumptions I've made about the JSON you've provided. Is there a way you can link to a paste of the full JSON file?
Create two simple structs to hold your data (I didn't add all fields here)
struct PriceInfo {
let avg12h: String
let avg1h: String
let rates: [Rate]
}
struct Rate {
let last: String
}
then after converting json you can map it to a dictionary of [String: PriceInfo] where the key is the currency code
do {
if let json = try JSONSerialization.jsonObject(with: content) as? [String: Any] {
let prices: [String: PriceInfo] = json.mapValues {
let dict = $0 as? [String: Any]
let avg12h = dict?["avg_12h"] as? String ?? ""
let avg1h = dict?["avg_1h"] as? String ?? ""
let rates = dict?["rates"] as? [String: String] ?? [:]
return PriceInfo(avg12h: avg12h, avg1h: avg1h, rates: rates.compactMap { rate in Rate(last: rate.value) } )
}
}
} catch {
print(error)
return
}
Try to use CodingKey, it will be more clearer and JSONDecoder().decode method. I assume that you use any JsonViewer
I am new to Swift and trying basic JSON parsing by following tutorials. I want to print a field of a JSON file, but it is not working.
Although the link exists, and I am using the same link I used for a previous tutorial, it returns rather than moved on to accessing the JSON.
I understand there is an "easier" way to do it in Swift4 using Decoder, but I received an error when I did it that way.
Here is the structure I am using:
struct Tester {
var userId: Int
var id: Int
var title: String
var body: String
init(json: [String: Any]){
userId = json["userId"] as? Int ?? -10
id = json["id"] as? Int ?? -400
title = json["title"] as? String ?? ""
body = json["body"] as? String ?? ""
}
}
And here is the code that is trying to access the JSON entries
#IBAction func printIDTitle(_ sender: Any) {
guard let url = URL(string: "https://jsonplaceholder.typicode.com/posts") else { return }
let session = URLSession.shared
session.dataTask(with: url) { (data, response, error) in
if let response = response {
print(response)
}
guard let data = data else { return }
do {
print("here 0\n")
guard let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] else {
print(error)
return
}
print("here 0.5\n")
print("here 1\n")
let d = Tester(json: json)
print(d.id)
print(d.title)
print("here 2\n")
} catch let error {
print(error)
}
}.resume()
}
The "here 0" is the only print that shows up.
What could be my issue?
The root is an array so change
guard let json = try JSONSerialization.jsonObject(with: data, options:[]) as? [[String: Any]] else {
print(error)
return
}
Or better
let res = try! JSONDecoder().decode([Root].self, from:data)
struct Root: Codable {
let userId, id: Int
let title, body: String
}
i have a problem by a code of me in swift. I do a request to webserver by httpMethod POST. This request is ok. I get a response and data inside the data value. The data looks like JSON
{"pushValues": {"devicePushGlobal":"1","devicePushNewProducts":"1","devicePushNewOffer":"1"}}
Then I will load this response data to set buttons based on the response data. But i fail to write this code. Can someone help me please? :)
Error Code
Cannot invoke 'jsonObject' with an argument list of type '(with: NSString)'
// i tested with other options but i always fail :-(
I comment the error in the code ....
let url = "https://URL.php"
let request = NSMutableURLRequest(url: NSURL(string: url)! as URL)
let bodyData = "token=" + (dts)
request.httpMethod = "POST"
request.httpBody = bodyData.data(using: String.Encoding.utf8);
NSURLConnection.sendAsynchronousRequest(request as URLRequest, queue: OperationQueue.main) {
(response, data, error) in
// here i get the result of
// {"pushValues": {"devicePushGlobal":"1","devicePushNewProducts":"1","devicePushNewOffer":"1"}}
var str = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
var names = [String]()
// here i will get each value of pushValues to add to the array names
do {
if let data = str,
// ... and here is the error code by xcode ::: ==> Cannot invoke 'jsonObject' with an argument list of type '(with: NSString)'
// i tested with other options but i always fail :-(
let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
let blogs = json["pushValues"] as? [[String: Any]] {
for blog in blogs {
if let name = blog["devicePushGlobal"] as? String {
print(name)
names.append(name)
}
}
}
} catch {
print("Error deserializing JSON: \(error)")
}
// names array is empty
print(names)
}
Thank you for your help
You shouldn't decode the JSON response into an NSString using var str = NSString(data: data!, encoding: String.Encoding.utf8.rawValue). JSONSerialization.jsonObject() expects a Data object as an input argument, so just safely unwrap the optional data variable and use that as the input argument:
if let responesData = data, let json = try JSONSerialization.jsonObject(with: responseData) as? [String: Any], let blogs = json["pushValues"] as? [String: Any]
The full code using native Swift types:
...
let request = URLRequest(url: URL(string: url)!)
...
URLSession.shared.dataTask(with: request, completionHandler: {
(response, data, error) in
var names = [String]()
do {
if let responseData = data, let json = try JSONSerialization.jsonObject(with: responseData) as? [String: Any], let blogs = json["pushValues"] as? [String: Any]{
if let name = blog["devicePushGlobal"] as? Int {
print(name)
names.append(name)
}
if let newProducts = blog["devicePushNewProducts"] as? Int{}
if let newOffers = blog["devicePushNewOffers"] as? Int{}
}
} catch {
print("Error deserializing JSON: \(error)")
}
// names array is empty
print(names)
}).resume()
I am trying to parse my json data in swift 3.0. I am using Alamofire 4.0+
Here is my json
{
"token":
"eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJleHAiOjE1MDQ0MjgzNzgxMTF9.CNonyvtQbRgaqqkdPO5KwqpVaUmlGrpaTqlBxmvaX80",
"expires": 1504428378111,
"user":
[{"user_id":13,"user_first_name":"Himanshu","user_last_name":"Srivastava","full_name":"Himanshu Srivastava"}]
}
Here is my model class to hold these values
import Foundation
import ObjectMapper
class LoginResult:Mappable{
var token:String?
var expires:Double?
var users:[[String:Any]]?
required init?(map:Map){
}
func mapping(map:Map)->Void{
self.token <- map["token"]
self.expires <- map["expires"]
self.users <- map["user"]
}
}
None of the solution available on internet worked for me. How can I parse this json and map to the model class?
Any help here?
I was mistaken, the value for key user is indeed a regular array.
This is a solution without a third party mapper and with an extra User struct (by the way the value for key expires is an Int rather than Double).
Assuming the user data comes from a database which always sends all fields the user keys are forced unwrapped. If this is not the case use optional binding also for the user data:
struct User {
let firstName : String
let lastName : String
let fullName : String
let userID : Int
}
class LoginResult {
let token : String
let expires : Int
var users = [User]()
init(json : [String:Any]) {
self.token = json["token"] as? String ?? ""
self.expires = json["expires"] as? Int ?? 0
if let users = json["user"] as? [[String:Any]] {
self.users = users.map { User(firstName: $0["user_first_name"] as! String,
lastName: $0["user_last_name"] as! String,
fullName: $0["full_name"] as! String,
userID: $0["user_id"] as! Int)
}
}
}
}
let json = "{\"token\":\"eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJleHAiOjE1MDQ0MjgzNzgxMTF9.CNonyvtQbRgaqqkdPO5KwqpVaUmlGrpaTqlBxmvaX80\",\"expires\":504428378111,\"user\":[{\"user_id\":13,\"user_first_name\":\"Himanshu\",\"user_last_name\":\"Srivastava\",\"full_name\":\"Himanshu Srivastava\"}]}"
let jsonData = json.data(using: .utf8)!
do {
if let userData = try JSONSerialization.jsonObject(with: jsonData) as? [String:Any] {
let loginResult = LoginResult(json: userData)
print(loginResult.users[0])
// do something with loginResult
}
} catch {
print(error)
}
Here is the answer with map replaced by dictionary. Don't forget to handle error or unwrap carefully :)
let str = "{\"token\": \"eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJleHAiOjE1MDQ0MjgzNzgxMTF9.CNonyvtQbRgaqqkdPO5KwqpVaUmlGrpaTqlBxmvaX80\",\"expires\": 1504428378111,\"user\": [{\"user_id\":13,\"user_first_name\":\"Himanshu\",\"user_last_name\":\"Srivastava\",\"full_name\":\"Himanshu Srivastava\"}]}"
let data = str.data(using: .utf8)
do{
let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? [String: Any]
//Pass this json into the following function
}catch let error{
}
func mapping(json:[String: Any]?)->Void{
self.token <- json?["token"] as? String
self.expires <- json?["expires"] as? Double
self.users <- json?["user"] as? [[String: Any]]
}
I'm trying to parse a json but I have some difficulties with the data types and notably the AnyObject type + downcasting.
Let's consider the following json (it's an extract of a full json).
{ "weather":
[
{
"id":804,
"main":"Clouds",
"description":"overcast clouds",
"icon":"04d"
}
],
}
To me, the json can be described as follow :
- json: Dictionary of type [String: AnyObject] (or NSDictionary, so = [NSObject, AnyObject] in Xcode 6 b3)
- "weather": Array of type [AnyObject] (or NSArray)
- Dictionary of type [String: AnyObject] (or NSDictionary, so = [NSObject, AnyObject] in Xcode 6 b3)
My json is of type AnyObject! (I use JSONObjectWithData to get the JSON from a URL).
I then want to access the weather Dictionary. Here is the code I wrote.
var localError: NSError?
var json: AnyObject! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &localError)
if let dict = json as? [String: AnyObject] {
if let weatherDictionary = dict["weather"] as? [AnyObject] {
// Do stuff with the weatherDictionary
}
}
Here is the error I got
Playground execution failed: error: <EXPR>:28:56: error: '[AnyObject]' is not a subtype of '(String, AnyObject)'
if let weatherDictionary = dict["weather"] as? [AnyObject] {
I don't understand why dict["weather"] is compared to a subtype of (String, AnyObject) and not AnyObject.
I declared my dictionary as [String: AnyObject], so I i access a value using the String key, I should have an AnyObject, no ?
If I use NSDictionary instead of [String: AnyObject], it works.
If I use NSArray instead of [AnyObject], it works.
- The Xcode 6 beta 3 release notes tell that "NSDictionary* is now imported from Objective-C APIs as [NSObject : AnyObject].".
- And the Swift book: "When you bridge from an NSArray object to a Swift array, the resulting array is of type [AnyObject]."
EDIT
I forgot to force unwrapping the dict["weather"]!.
if let dict = json as? [String: AnyObject] {
println(dict)
if let weatherDictionary = dict["weather"]! as? [AnyObject] {
println("\nWeather dictionary:\n\n\(weatherDictionary)")
if let descriptionString = weatherDictionary[0]["description"]! as? String {
println("\nDescription of the weather is: \(descriptionString)")
}
}
}
Note that we should double check for the existence of the first Optional.
if let dict = json as? [String: AnyObject] {
for key in ["weather", "traffic"] {
if let dictValue = dict[key] {
if let subArray = dictValue as? [AnyObject] {
println(subArray[0])
}
} else {
println("Key '\(key)' not found")
}
}
}
This works fine for me in the playground and in the terminal using env xcrun swift
UPDATED FOR SWIFT 4 AND CODABLE
Here is a Swift 4 example using the Codable protocol.
var jsonStr = "{\"weather\":[{\"id\":804,\"main\":\"Clouds\",\"description\":\"overcast clouds\",\"icon\":\"04d\"}],}"
struct Weather: Codable {
let id: Int
let main: String
let description: String
let icon: String
}
struct Result: Codable {
let weather: [Weather]
}
do {
let weather = try JSONDecoder().decode(Result.self, from: jsonStr.data(using: .utf8)!)
print(weather)
}
catch {
print(error)
}
UPDATED FOR SWIFT 3.0
I have updated the code for Swift 3 and also showed how to wrap the parsed JSON into objects. Thanks for all the up votes!
import Foundation
struct Weather {
let id: Int
let main: String
let description: String
let icon: String
}
extension Weather {
init?(json: [String: Any]) {
guard
let id = json["id"] as? Int,
let main = json["main"] as? String,
let description = json["description"] as? String,
let icon = json["icon"] as? String
else { return nil }
self.id = id
self.main = main
self.description = description
self.icon = icon
}
}
var jsonStr = "{\"weather\":[{\"id\":804,\"main\":\"Clouds\",\"description\":\"overcast clouds\",\"icon\":\"04d\"}],}"
enum JSONParseError: Error {
case notADictionary
case missingWeatherObjects
}
var data = jsonStr.data(using: String.Encoding.ascii, allowLossyConversion: false)
do {
var json = try JSONSerialization.jsonObject(with: data!, options: [])
guard let dict = json as? [String: Any] else { throw JSONParseError.notADictionary }
guard let weatherJSON = dict["weather"] as? [[String: Any]] else { throw JSONParseError.missingWeatherObjects }
let weather = weatherJSON.flatMap(Weather.init)
print(weather)
}
catch {
print(error)
}
-- Previous Answer --
import Foundation
var jsonStr = "{\"weather\":[{\"id\":804,\"main\":\"Clouds\",\"description\":\"overcast clouds\",\"icon\":\"04d\"}],}"
var data = jsonStr.dataUsingEncoding(NSASCIIStringEncoding, allowLossyConversion: false)
var localError: NSError?
var json: AnyObject! = NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers, error: &localError)
if let dict = json as? [String: AnyObject] {
if let weather = dict["weather"] as? [AnyObject] {
for dict2 in weather {
let id = dict2["id"]
let main = dict2["main"]
let description = dict2["description"]
println(id)
println(main)
println(description)
}
}
}
Since I'm still getting up-votes for this answer, I figured I would revisit it for Swift 2.0:
import Foundation
var jsonStr = "{\"weather\":[{\"id\":804,\"main\":\"Clouds\",\"description\":\"overcast clouds\",\"icon\":\"04d\"}],}"
var data = jsonStr.dataUsingEncoding(NSASCIIStringEncoding, allowLossyConversion: false)
do {
var json = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
if let dict = json as? [String: AnyObject] {
if let weather = dict["weather"] as? [AnyObject] {
for dict2 in weather {
let id = dict2["id"] as? Int
let main = dict2["main"] as? String
let description = dict2["description"] as? String
print(id)
print(main)
print(description)
}
}
}
}
catch {
print(error)
}
The biggest difference is that the variable json is no longer an optional type and the do/try/catch syntax. I also went ahead and typed id, main, and description.
Try:
https://github.com/dankogai/swift-json
With it you can go like this:
let obj:[String:AnyObject] = [
"array": [JSON.null, false, 0, "", [], [:]],
"object":[
"null": JSON.null,
"bool": true,
"int": 42,
"double": 3.141592653589793,
"string": "a α\t弾\n𪚲",
"array": [],
"object": [:]
],
"url":"http://blog.livedoor.com/dankogai/"
]
let json = JSON(obj)
json.toString()
json["object"]["null"].asNull // NSNull()
json["object"]["bool"].asBool // true
json["object"]["int"].asInt // 42
json["object"]["double"].asDouble // 3.141592653589793
json["object"]["string"].asString // "a α\t弾\n𪚲"
json["array"][0].asNull // NSNull()
json["array"][1].asBool // false
json["array"][2].asInt // 0
json["array"][3].asString // ""
Using my library (https://github.com/isair/JSONHelper) you can do this with your json variable of type AnyObject:
var weathers = [Weather]() // If deserialization fails, JSONHelper just keeps the old value in a non-optional variable. This lets you assign default values like this.
if let jsonDictionary = json as? JSONDictionary { // JSONDictionary is an alias for [String: AnyObject]
weathers <-- jsonDictionary["weather"]
}
Had your array not been under the key "weather", your code would have been just this:
var weathers = [Weather]()
weathers <-- json
Or if you have a json string in your hands you can just pass it as well, instead of creating a JSON dictionary from the string first. The only setup you need to do is writing a Weather class or struct:
struct Weather: Deserializable {
var id: String?
var name: String?
var description: String?
var icon: String?
init(data: [String: AnyObject]) {
id <-- data["id"]
name <-- data["name"]
description <-- data["description"]
icon <-- data["icon"]
}
}