I have a JSON array created using this call:
guard let json = (try? JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [Any] else {
print("This is not JSON!!!")
return
}
I am trying to get elements from the JSON objects in the array to display them using the following code:
struct sWidget: Codable{
var createdBy: String
var createdDate: Date
var status: String
var widgetNumber: String
var updatedBy: String
var updatedDate: Date
}
do {
let decoder = JSONDecoder()
for (index, value) in json.enumerated() {
let currentWidget = try decoder.decode(sWidget.self, from: json[index] as! Data)
let currentNum = currentWidget.widgetNumber
//print(currentNum)
widgetNums.append(currentNum)
}
}
catch {
print("decoding error")
}
The code compiles but when I run it I get this error in the output:
Could not cast value of type '__NSDictionaryM' (0x1063c34f8) to
'NSData' (0x1063c1090). 2018-08-09 09:41:02.666713-0500
TruckMeterLogScanner[14259:1223764] Could not cast value of type
'__NSDictionaryM' (0x1063c34f8) to 'NSData' (0x1063c1090).
I am still investigating but any tips would be helpful.
Did you try that fetching objects like above mentioned? Because i see that you are using Codable. Fetching is very simple with that actually.
let yourObjectArray = JSONDecoder().decode([sWidget].self, data: json as! Data)
May be this line can be buggy but you can fetch them with one line.
Extending #Cemal BAYRI's answer:
JSONDecoder() throws, so make sure to either us try? or try (don't forget do-catch with try)
guard let data = content as? Data else {
return [sWidget]()
}
let jsonDecoder = JSONDecoder()
1. try?
let yourObjectArray = try? jsonDecoder.decode([sWidget].self, data: data)
2. try
do {
let yourObjectArray = try jsonDecoder.decode([sWidget].self, data: data)
} catch let error {
}
Note: You would need to take care of Data and Date formatting. Below is an example for Date:
jsonDecoder.dateDecodingStrategy = .iso8601
You can also check it out here
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
So I have a JSON file that I need to parse and update labels and image. In my storyboard I have 4 labels (image of an animal, region, it's weight and length) and uiimage where I need to put it's picture.
I need to update labels and image by parsing JSON.
This is how far I was able to get to...
My JSON look like this:
"data":[
{
"name":"Lion",
"thumbnail":"https://kopelion.org/wp-content/uploads/2016/10/Kimani.jpg",
"region":"Africa",
"stats":{
"max_weight":180,
"length":250
}
}
]
I tried to get into this by writing:
override func viewDidLoad() {
super.viewDidLoad()
guard let path = Bundle.main.path(forResource: "data", ofType: "json") else { return }
let url = URL(fileURLWithPath: path)
do {
let data = try Data(contentsOf: url)
let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers)
print(json)
guard let array = json as? [Any] else { return }
for animal in array {
guard let animalDict = animal as? [String: Any] else { return }
guard let animalName = animalDict["name"] as? String else { return }
guard let animalRegion = animalDict["region"] as? String else { return }
guard let animalStats = animalDict["stats"] as? String else { return }
print(animalName)
print(animalRegion)
print(animalStats)
}
} catch {
print(error)
}
}
First thing first, most of the times the main culprit is json file itself, as in your case.
You need to fix the json code first, by adding "{" at the top and "}" at the bottom of your json file's code.
This will make it valid json
And then do the following
Replace your code lines:
// 1
guard let array = json as? [Any] else { return }
// 2
guard let animalStats = animalDict["stats"] as? String else { return }
with this:
// 1
guard let dictionary = json as? [String:[Any]] else { return }
guard let array = dictionary["data"] else { return }
//2
guard let animalRegion = animalDict["region"] as? String else { return }
Quik tip : 1. Check your json using online tools like https://codebeautify.org/jsonviewer
Try to use JSONDecoder and JSONEncoder instead of JSONSerialization
You'll need to have properties in your class for the storyboard items you want to set. e.g.,:
#IBOutlet weak var name: UILabel! // outside functions but inside class, and hooked up in Storyboard
// inside viewDidLoad
name.text = animalDict["name"] as? String
I wouldn't bother with the intermediate variables unless you really need them.
As you are responsible for the JSON delete the enclosing dictionary data, it's not needed.
[{
"name":"Lion",
"thumbnail":"https://kopelion.org/wp-content/uploads/2016/10/Kimani.jpg",
"region":"Africa",
"stats":{
"max_weight":180,
"length":250
}
}]
Create two structs
struct Animal: Decodable {
let name: String
let thumbnail: URL
let region: String
let stats: Stats
}
struct Stats: Decodable {
let maxWeight, length: Int
}
In the view controller declare a data source array
var animals = [Animal]()
In viewDidLoad parse the data with JSONDecoder and assign the result to the data source array
override func viewDidLoad() {
super.viewDidLoad()
let url = Bundle.main.url(forResource: "data", withExtension: "json")!
let data = try! Data(contentsOf: url)
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
self.animals = try! decoder.decode([Animal].self, from: data)
}
All guards and trys are actually not needed. The file must exist at compile time and cannot be modified at runtime so the code must not crash.
You can get the animal properties with
let animal = animals[0]
let name = animal.name
let weight = animal.stats.weight
print(name, weight)
Assuming there are more animals in the JSON use a loop
for animal in animals {
let name = animal.name
let weight = animal.stats.weight
print(name, weight)
}
How to update the labels is unclear because there is no significant information about the design in your question.
To get the image load it asynchronously with URLSession
I wanted to know the best way to parse json response of below type in Swift 4. Response is double encoded -
\"[{\\"value\\":\\"International University \\\\"MITSO\\\\"\\",\\"id\\":\\"a1v24000000uOrPAAU\\",\\"addlFields\\":[\\"Mi?narodny Universitet \\\\"MITSO\\\\"\\"]}]\"
Here is the data in NSData format -
(String) $R0 = "data: Optional(146 bytes) as NSData: <225b7b5c 2276616c 75655c22 3a5c2249 6e746572 6e617469 6f6e616c 20556e69 76657273 69747920 5c5c5c22 4d495453 4f5c5c5c 225c222c 5c226964 5c223a5c 22613176 32343030 30303030 754f7250 4141555c 222c5c22 6164646c 4669656c 64735c22 3a5b5c22 4d693f6e 61726f64 6e792055 6e697665 72736974 6574205c 5c5c224d 4954534f 5c5c5c22 5c225d7d 5d22>"
As you see value of the key "value" has a inner double quotes(").
JSONSerialization consider this as invalid Json.
Any help will be greatly appreciated.
The content of your data as String is as follows:
"[{\"value\":\"International University \\\"MITSO\\\"\",\"id\":\"a1v24000000uOrPAAU\",\"addlFields\":[\"Mi?narodny Universitet \\\"MITSO\\\"\"]}]"
Seeing the actual content without extra double-quotes and backslashes needed to show String as String-literal, it looks like some valid JSON is embedded in a String.
This may happen when the server side code double-encodes the data. You should better tell your server side engineer to fix the issue, but if it is difficult or would take long time, you can double-decode it.
Testing code:
import Foundation
let dataStr = "<225b7b5c 2276616c 75655c22 3a5c2249 6e746572 6e617469 6f6e616c 20556e69 76657273 69747920 5c5c5c22 4d495453 4f5c5c5c 225c222c 5c226964 5c223a5c 22613176 32343030 30303030 754f7250 4141555c 222c5c22 6164646c 4669656c 64735c22 3a5b5c22 4d693f6e 61726f64 6e792055 6e697665 72736974 6574205c 5c5c224d 4954534f 5c5c5c22 5c225d7d 5d22>".dropFirst().dropLast().replacingOccurrences(of: " ", with: "")
let byteArr = stride(from: 0, to: dataStr.count, by: 2).map{(index: Int)->UInt8 in
let start = dataStr.index(dataStr.startIndex, offsetBy: index)
let end = dataStr.index(start, offsetBy: 2)
return UInt8(dataStr[start..<end], radix: 16)!
}
let responseData = Data(bytes: byteArr)
print(responseData as NSData)
Check here, whether the print statement output is exactly the same as your sample response. (If you want to test the following code with your actual data than sample response, use just let responseData = result as! Data instead of above lines.)
So, you just need to use JSONSerialization twice:
block: do {
let firstDecoded = try JSONSerialization.jsonObject(with: responseData, options: .allowFragments) as! String
let firstDecodedData = firstDecoded.data(using: .utf8)!
let secondDecoded = try JSONSerialization.jsonObject(with: firstDecodedData)
//Code below is an example of using decoded result.
guard let resultArray = secondDecoded as? [[String: Any]] else {
print("result is not an Array of Dictionary")
break block
}
print(resultArray)
if
let addlFields = resultArray[0]["addlFields"] as? [String],
let firstAddl = addlFields.first
{
print(firstAddl)
}
} catch {
print(error)
}
Outputs: (Omitting some output for print(responseData as NSData).)
[["id": a1v24000000uOrPAAU, "value": International University "MITSO", "addlFields": <__NSSingleObjectArrayI 0x100e40c80>(
Mi?narodny Universitet "MITSO"
)
]]
Mi?narodny Universitet "MITSO"
(You may find some parts like <__NSSingleObjectArrayI 0x100e40c80> are strange, but it's just a problem of generating default description and you can access the elements as an Array.)
Anyway, please try and see what you can get with my code above.
#OOPer thank you for the solution. Appreciate you giving your time.
Solution worked as expected. Pasting code here which may help others.
Here is how I am doing -
func getData(text:String, callback:#escaping (_ result: Array<somedata>?,_ error:Error?) -> Void) {
let params = ["search":text]
getDataSomeAPI(url: "http:\\xyz.com\fdf", params: params) { (result, error) in
if error == nil {
do {
//Response is double encoded
if let firstDecoded = try JSONSerialization.jsonObject(with: result as! Data, options: .allowFragments) as? String
{
let firstDecodedData = firstDecoded.data(using: .utf8)!
if let secondDecoded = try JSONSerialization.jsonObject(with: firstDecodedData) as? NSArray {
var array = [somedata]()
for obj in secondDecoded {
Mapper<somedata>().map(JSONObject: obj).then { mappedObj in
array.append(mappedObj)
}
}
callback(array,nil)
}
}
}
catch {
//Handle unexpected data format
let error = NSError(domain: "",
code: 0,
userInfo: nil)
let sErr = Error(err: error)
callback(nil, sErr)
}
} else {
callback(nil, error)
}
}
}
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've looked around but I don't find an answer to fix this error that has been bugging me. I tried adding a "as! NSMutableArray" but that gave me another error. Any ideas on how to fix it? I converted my project from Objective-C to Swift, so hopefully the code is all good I had 20+ errors now I'm down to 3 errors. Thank you.
Error Message:
'jsonObject' produces 'Any', not the expected contextual result type 'NSMutableArray'
Code for retrieving data from server
// Retrieving Data from Server
func retrieveData() {
let getDataURL = "http://ip/example.org/json.php"
let url: NSURL = NSURL(string: getDataURL)!
do {
let data: NSData = try NSData(contentsOf: url as URL)
jsonArray = JSONSerialization.jsonObject(with: data, options: nil)
}
catch {
print("Error: (data: contentsOf: url)")
}
// Setting up dataArray
var dataArray: NSMutableArray = []
// Looping through jsonArray
for i in 0..<jsonArray.count {
// Create Data Object
let dID: String = (jsonArray[i] as AnyObject).object(forKey: "id") as! String
let dName: String = (jsonArray[i] as AnyObject).object(forKey: "dataName") as! String
let dStatus1: String = (jsonArray[i] as AnyObject).object(forKey: "dataStatus1") as! String
let dStatus2: String = (jsonArray[i] as AnyObject).object(forKey: "dataStatus2") as! String
let dURL: String = (jsonArray[i] as AnyObject).object(forKey: "dataURL") as! String
// Add Data Objects to Data Array
dataArray.add(Data(dataName: dName, andDataStatus1: dStatus1, andDataStatus2: dStatus2, andDataURL: dURL, andDataID: dID))
}
self.myTableView.reloadData()
}
The jsonObject function will return a value of type Any but the jsonArray's type of NSMutableArray. And this function will throw an error if something is wrong, put a try keyword before it. In my experience, let change the type of jsonArray to array of dictionary, so you will extract data with ease.
do {
let data: Data = try Data(contentsOf: url as URL)
let jsonArray: [[String: AnyObject]] = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as! [[String: AnyObject]]
print("json: \(jsonArray)")
for dict in jsonArray {
let dataName = dict["dataName"] as! String
print("dataName: \(dataName)")
}
}
catch {
print("Error: (data: contentsOf: url)")
}