Swift JSON parsing - json

I am working on an iOS weather app and need some help getting some values with JSON. I am trying to pull the value of id in the weather object. I am getting a value of nil when I debug. Could someone please help me with the logic? Here is the JSON request and Swift code.
{
"coord":{
"lon":138.93,
"lat":34.97
},
"weather":[
{
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"01n"
}
],
"base":"cmc stations",
"main":{
"temp":292.181,
"pressure":1005.21,
"humidity":100,
"temp_min":292.181,
"temp_max":292.181,
"sea_level":1014.59,
"grnd_level":1005.21
},
"wind":{
"speed":3.41,
"deg":78.0005
},
"clouds":{
"all":0
},
"dt":1464801034,
"sys":{
"message":0.003,
"country":"JP",
"sunrise":1464723086,
"sunset":1464774799
},
"id":1851632,
"name":"Shuzenji",
"cod":200
}
Here is my Swift snippet:
let requestURL: NSURL = NSURL(string: "http://api.openweathermap.org/data/2.5/weather?lat=35&lon=139&appid=6361e893fa064b1bfeaca686cd0929cc")!
let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: requestURL)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(urlRequest) {
(data, response, error) -> Void in
let httpResponse = response as! NSHTTPURLResponse
let statusCode = httpResponse.statusCode
if (statusCode == 200) {
print("JSON Downloaded Sucessfully.")
do{
let json = try NSJSONSerialization.JSONObjectWithData(data!, options:.AllowFragments)
if let today = json["weather"] as? [[String: AnyObject]] {
//this is pulling 4 key value pairs
for weather in today {
let id = weather["id"] as? String
self.trumpDescription.text=id;
print(id)
}
}
}
catch {
print("Error with Json: \(error)")
}
}
}
task.resume()
}

The problem lies in your cast to a string. If you do not cast the id as a String, it will print "800" as an Int.
When you are grabbing the id from the json and converting it to a string, it reads the string and includes the new line character.
I played around in the playground
So you are correctly getting to the spot in the json, but you need to unwrap your optional.

You can also use the nil coalescing operator to unwrap optionals so you don't have to have a bunch of if lets:
let id = weather["id"] as? String ?? ""
Which will either set id to the value or to "" if it doesn't exist.

try this in your code:
let id = weather["id"]?.stringValue
instead of this:
let id = weather["id"] as? String
And see the magic!
Edit for explanation:
As this answer worked for you, let me tell you why it did.
The id is being sent as integer from the server side. When you do weather["id"] it returns object of type AnyObject?. When you do weather["id"] as? String the casting fails thus you were getting nil.

Related

Swift read from JSON dictionary

I am sending an Alamofire request and inside of my completion handler I have:
if let jsonData = response.result.value {
result = jsonData
guard let data = result.data(using: .utf8) else { return}
guard let dictionary = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] else {
print("Could not cast JSON content as a Dictionary<String, Any>")
return
}
print("dictionary: \(dictionary)")
if dictionary["status"] as! String == "false"{
//Do something
}
}
else{
result = "\(response.error)"
}
The result of printing dictionary is ["status":false, "value":A1]. Ultimately I want to use status for my if statement. However I get a crash on the if statement line: if dictionary["status"] as! String == "false" of Fatal error: Unexpectedly found nil while unwrapping an Optional value. I also tried changing the line to if dictionary["status"] as! Bool == false and I get the exact same error.
The json as returned from the request is:
{
"value": "A1",
"status": "false"
}
So my question is, what is the correct way to get the value for status out of dictionary?
Would something like this work?
struct jsonOut: Codable {
let value: String
let status: String
}
if let jsonData = response.result.value {
result = jsonData
guard let data = result.data(using: .utf8)
let status = try JSONDecoder().decode(jsonOut.self, from: data)
}
Since the JSON has the format:
{
"value": "A1",
"status": "false"
}
The correct way is using Codable with the same format as the JSON:
struct jsonOut: Codable {
let value: String
let status: String
}
if let jsonData = response.result.value {
result = jsonData
guard let data = result.data(using: .utf8)
let statusData = try JSONDecoder().decode(jsonOut.self, from: data)
print("status: \(statusData.status)"
}

Accessing JSON Array from API response in Swift

I am brand new to writing swift so any tips on improvement/best practices are welcome but my main issue is that I am having trouble accessing a nested JSON array list. I am using this free API and trying to show a list of characters https://swapi.dev/api/people/
Please see the code snippet below.
When I print the type its : Optional<Any> and when i print json["results"] it prints the array like:
Optional(<__NSArrayI 0x600000fe31e0>(
{
"birth_year" = 19BBY;
created = "2014-12-09T13:50:51.644000Z";
....
I have tried several different things but have been unsuccessful. Could someone please give some advice on how I might iterate the list under json["results"?
func onLoad() -> Void {
let url = URL(string: "https://swapi.dev/api/people")
guard let requestUrl = url else { fatalError() }
// Create URL Request
var request = URLRequest(url: requestUrl)
// Specify HTTP Method to use
request.httpMethod = "GET"
// Send HTTP Request
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
// Check if Error took place
if let error = error {
print("Error took place \(error)")
return
}
// Convert HTTP Response Data to a simple String
if let data = data {
// let json = try? JSONSerialization.jsonObject(with: data, options: [])
do {
if let json = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
// try to read out a string array
print(type(of: json["results"]))
print(json["results"])
}
} catch let error as Error {
print("Failed to load: \(error.localizedDescription)")
}
}
}
task.resume()
}
Thanks for any help!
You should really be using Decodable rather than trying to parse it with JSON as that can easily lead to errors as you are accessing values by strings and it doesn't allow the IDE to help you.
You need to create some objects that describe what you are getting in your response.
Your main json response is made up of the following
{
"count": 82,
"next": "http://swapi.dev/api/people/?page=2",
"previous": null,
"results": [...]
}
This allows you to create a People struct that conforms to Decodable.
struct People: Decodable {
let count: Int
let next: URL?
let previous: URL?
let results: [Person]
}
The results array is really what you are after as that contains all the information about a person.
{
"name": "Luke Skywalker",
"height": "172",
"mass": "77",
"hair_color": "blond",
"skin_color": "fair",
"eye_color": "blue",
"birth_year": "19BBY",
"gender": "male",
"homeworld": "http://swapi.dev/api/planets/1/",
"films": [
"http://swapi.dev/api/films/1/",
"http://swapi.dev/api/films/2/",
"http://swapi.dev/api/films/3/",
"http://swapi.dev/api/films/6/"
],
"species": [],
"vehicles": [
"http://swapi.dev/api/vehicles/14/",
"http://swapi.dev/api/vehicles/30/"
],
"starships": [
"http://swapi.dev/api/starships/12/",
"http://swapi.dev/api/starships/22/"
],
"created": "2014-12-09T13:50:51.644000Z",
"edited": "2014-12-20T21:17:56.891000Z",
"url": "http://swapi.dev/api/people/1/"
}
We can represent this with the following struct called Person that also conforms to Decodable
struct Person: Decodable {
let name: String
let height: String
let mass: String
let hairColor: String
let skinColor: String
let birthYear: String
let gender: Gender
let homeworld: String
let films: [URL]
let species: [URL]
let vehicles: [URL]
let starships: [URL]
let created: Date
let edited: Date
let url: URL
}
enum Gender: String, Decodable {
case male
case female
case unknown = "n/a"
}
Note a couple of differences between the names in the struct and the names in the object that you are getting back. eg hair_color (snakecase) and hairColor (camelCase) In Swift it is common to write it the latter way and when we use decodable we can tell our decoder to use a custom key decoding strategy. Also note that I have used an enum for Gender. This isn't required and we could have just used a String. Also note that created and edited are Dates, however they are not iso8601 compliant but we can also specify a custom date decoding strategy.
Here is how we can decode the data that you have received.
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'"
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
decoder.dateDecodingStrategy = .formatted(dateFormatter)
let people = try decoder.decode(People.self, from: data)
Now we can put this all together in your network request to get the following:
func onLoad() {
let url = URL(string: "https://swapi.dev/api/people")
guard let requestUrl = url else { fatalError() }
// Create URL Request
var request = URLRequest(url: requestUrl)
// Specify HTTP Method to use
request.httpMethod = "GET"
// Send HTTP Request
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
// Check if Error took place
if let error = error {
print("Error took place \(error)")
return
}
// Convert HTTP Response Data to a simple String
if let data = data {
do {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'"
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
decoder.dateDecodingStrategy = .formatted(dateFormatter)
let people = try decoder.decode(People.self, from: data)
people.results.forEach { person in print(person) }
} catch {
print("Failed to load: \(error)")
}
}
}
task.resume()
}
Cast results as an Array of Dictionary. Here's how
if let data = data {
do {
if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
let results = json["results"] as? [[String: Any]] {
for result in results {
print(result)
}
}
} catch {
print("Failed to load: \(error.localizedDescription)")
}
}
Better Approach: Use Codable, JSONSerialization feels bit outdated.
Related Links:
https://developer.apple.com/documentation/swift/codable
https://www.swiftbysundell.com/basics/codable/

The JSON output does not contain a key: "value"

I have a JSON parsing issue with my Swift code below. The error I am getting says that my JSON output does not contain a key value.
My code:
Alamofire.request(url, method: .get, headers: headers).responseJSON { (response) -> Void in
let jsonValue = response.result.value as! NSDictionary
if let bpArray = jsonValue["value"] as? [NSDictionary]{
for results in bpArray {...}
Issue:
This conversion doesnt work: if let bpArray = jsonValue["value"] as? [NSDictionary]
My JSON Structure:
{
d: {
results: [
{
__metadata: {},
Key: "AFBWhULFHtKU4j4FhWCmKg==",
ParentKey: "AAAAAAAAAAAAAAAAAAAAAA==",
RootKey: "AFBWhULFHtKU4j4FhWCmKg==",
Partner: "MM-CARR-01",
Type: "2",
Description: "MM Demo Carrier Created for Single Stop / MA",
FrieghtOrder: {}
},
...
Assuming you want to access the results key so try like this:-
if let bpArray = jsonValue["results"] as? [String: AnyObject]{
//yourcode
}
Well your json structure haven't got any key named as value and that's why it's giving an error.
In order to get results array, you first need to get the object in which they are nested and for example 'g' in your case:
if let data = jsonValue["d"] as? [NSDictionary]{
if let resultsArray = data["results"] as? NSArray {
//your code
}
}
Please Use Swifty Json Pod And Try this code
pod 'SwiftyJSON'
In Your file where you get response
import SwiftyJSON
Then After Use This Code
switch response.result {
case .success(let JSON2):
print("Success with JSON: \(JSON2)")
// print("Request failed with error: \(response.response?.statusCode)")
if let response = JSON2 as? NSMutableDictionary
{
}
else if let response = JSON2 as? NSDictionary
{
if let data = response?.object(forKey: "d") as? NSDictionary
{
if let resultsArray = data?.object(forKey: "results") as? NSArray
{
}
}
}
else if JSON2 is NSArray
{
let swjson = JSON(response.result.value!)
print(swjson)
// callback(swjson,nil)
var myMutableDictionary = [AnyHashable: Any]()
myMutableDictionary["myArray"] = swjson
callback(myMutableDictionary as NSDictionary?,nil)
print("accc")
}
else if ((JSON2 as? String) != nil)
{
let userDic : [String : String] = ["quatid":JSON2 as! String]
print(userDic)
}
break
case .failure(let error):
print("Request failed with error: \(error)")
}
Remember it's better we not use NSArray & NSDictionary like things in SWIFT, SWIFT it self providing let, var keyword for various data type.
First you can create your model where you can save the data.
MyModel.swift
class MyModel: NSObject {
var ParentKey : Int?
init(jsonObject:[String:Any]) {
ParentKey = jsonObject["ParentKey"] as? String ?? ""
}
}
Viewcontroller.Swift
var myModel : [MyModel] = []
if let responseData = response["d"] as? [String:Any]{
if let dataObject = responseData["results"] as? [[String:Any]]{
self.myModel = dataObject.map({return MyModel(jsonObject: $0)})//for assigning data into model
}
}
As most people said, I was wrong with "value". Hussain's answer to using [String:AnyObject] Helped.
I am not sure if the below is neat to achieve, but it did the magic. App loaded as expected. Code expert below:
Solution:
if let bpData = jsonValue["d"] as? [String: AnyObject]{
for results in bpData {
let arrayInterim = results.value as? NSArray
for i in 0 ..< arrayInterim!.count {

Get data from json array swift 2

I'm trying to get data drom the json array, this is the code that i'm trying, the thing is that i would like to get only the name that is inside this json
{
"tag": "getuser",
"success": 1,
"error": 0,
"uid": "56108b7e651ad2.95653404",
"user": {
"name": "2",
"phone": "2",
"email": "2"
}
}
I tryied this
let jsonData:NSDictionary = try NSJSONSerialization.JSONObjectWithData(urlData!, options:NSJSONReadingOptions.MutableContainers ) as! NSDictionary
let name = jsonData["user"]
print("Nombre del usuarioes: \(name)")
But this prints the whole user data, name, phone and email, how can i be able to print only the name or only the email?
You don't have to use a library and you don't have to use key-value coding.
The same way you're already using subscripting for your dictionary with this:
let name = jsonData["user"]
you just have to continue subscripting to find your value.
Example:
do {
let jsonData = try NSJSONSerialization.JSONObjectWithData(urlData!, options: []) as! NSDictionary
let user = jsonData["user"]!
let name = user["name"]
print(name)
} catch {
print(error)
}
Even better with safe unwrapping:
do {
if let data = urlData, let jsonData = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? NSDictionary {
if let user = jsonData["user"] as? NSDictionary, let name = user["name"] as? String {
print(name)
}
}
} catch {
print(error)
}
Note: in JSON, a dictionary is defined by {} and an array is defined by []. What you have here is a dictionary containing a dictionary, not an array (cf your question title).
A great library to decode json is SwiftyJSON
you can get sub-scripted data from the json like so
import SwiftyJSON
if let dataFromString = jsonString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false) {
let json = JSON(data: dataFromString)
let name = json["user"]["name"].string
print(name)
}
Use your code, then get the field from jsonData by this:
let name = jsonData.valueForKeyPath("user.name") as! String
let email = jsonData.valueForKeyPath("user.email") as! String

How to parse this specific JSON data in Swift 2.0

I'm trying to parse Json Data from an API :
{
"title": "Mr. Robot",
"first_aired": "2015-06-24",
"network": "USA Network",
"channels": [
{
"id": 12,
"name": "USA",
"short_name": "usa",
"channel_type": "television"
}
],
The Code I'm use is:
var TVArray : [TVInfo] = []
var task : NSURLSessionTask?
func getJSON (urlString: String) {
let url = NSURL(string: urlString)!
let session = NSURLSession.sharedSession()
task = session.dataTaskWithURL(url) {(data, response, error) in
dispatch_async(dispatch_get_main_queue()) {
if (error == nil) {
self.updateJSON(data)
}
else {
}
}
}
task!.resume()
}
func updateJSON (data: NSData!) {
let JSONData = (try! NSJSONSerialization.JSONObjectWithData(data, options: []))
TVArray.removeAll(keepCapacity: true)
if let jsonArray = JSONData {
for j in jsonArray {
let title = jsonResult["title"] as! String
let firstAired = jsonResult["first_aired"] as! String
let network = jsonResult["network"] as! String
let channelName = JsonResult["channels"][0]["name"] as! String
let TV = TVInfo(title: title, firstAired: firstAired, network: network, channelName: channelName)
TVArray.append(TV)
}
}
collectionview.reloadData()
}
}
When I use the above code I get an error 'Initializer for conditional binding must have Optional type, not 'AnyObject'' in front of the line 'if let jsonArray = JsonData'. I've tried some methods I've seen on StackOverflow like the method in the link :
[Parsing JSON in swift 2.0
but it didn't work for me. I'm still a bit new to Swift, I really don't want to use SwiftyJSON. Is this the best way to parse this JSON data or is there a better way of doing it?
Since you've used NSJSONSerialization with try! (note the !, meaning it was forced) the value of JSONData is not an optional: you don't have to unwrap it with if let jsonArray = JSONData.
If you still want an optional value, use try? instead.
Otherwise you could also use try inside a do catch block to handle possible errors.
The type of JSONData is unknown, it needs to be known to be an Array for the following for loop.
use:
let JSONData = try! NSJSONSerialization.JSONObjectWithData(data!, options:[]) as! NSArray
You do not need:
if let jsonArray = JSONData {
because you have already crashed if JSONData is nil from the preceding try!
You are better with:
do {
let jsonArray = try NSJSONSerialization.JSONObjectWithData(data!, options:[]) as! NSArray
for j in jsonArray {
// ...
}
} catch {
// handle error
}
Because you have no control over the JSON you receive and crashing because of a server change is not a good idea.
Also really put some time into naming variables, JSONData is not data, it is an array obtained by parsing a JSON string.