When I try to run this project I am greeted with a "Use of unresolved identifier error." Here is the code I get the error on the line with
var jsonDict = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)
as! NSDictionary
let task : NSURLSessionDataTask = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
if((error) != nil) {
print(error!.localizedDescription)
} else {
let err: NSError?
do {
var jsonDict = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
} catch {
if(err != nil) {
print("JSON Error \(err!.localizedDescription)")
}
else {
//5: Extract the Quotes and Values and send them inside a NSNotification
let quotes:NSArray = ((jsonDict.objectForKey("query") as! NSDictionary).objectForKey("results") as! NSDictionary).objectForKey("quote") as! NSArray
dispatch_async(dispatch_get_main_queue(), {
NSNotificationCenter.defaultCenter().postNotificationName(kNotificationStocksUpdated, object: nil, userInfo: [kNotificationStocksUpdated:quotes])
})
}
}
}
})
can someone please help. Thank you.
You problem could be this line of code in the catch block.
let quotes:NSArray = ((jsonDict.objectForKey("query") as! NSDictionary).objectForKey("results") as! NSDictionary).objectForKey("quote") as! NSArray
In the above statement jsonDict is out of scope. You declared jsonDict in the do block but are trying to use it in the catch block.
Try Following:-
(Assuming JSON has a root node structure)
let urlRequest: NSMutableURLRequest = NSMutableURLRequest(URL: yourURL)
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) {
do{
let json = try NSJSONSerialization.JSONObjectWithData(data!, options:.AllowFragments)
if let queries = json["query"] as? [[String: AnyObject]] {
for query in queries {
if let quote = query["quote"] as? String {
self.quoteArr.append(quote)
}
}//for loop
dispatch_async(dispatch_get_main_queue(),{
// your main queue code
NSNotificationCenter.defaultCenter().postNotificationName(kNotificationStocksUpdated, object: nil, userInfo: [kNotificationStocksUpdated:quotes])
})//dispatch
}// if loop
}
catch
{
print("Error with Json: \(error)")
}
}
else
{
// No internet connection
// Alert view controller
// Alert action style default
}
this cobweb of code is exactly why SwiftyJSON library exists. I recommend it highly, it can be imported into your project using cocoapods.
using this library the resultant code would be
jsonQuery["query"]["results"]["quote"]
which is more readable and as you implement more APIs, much faster.
Related
Iam getting an error while i try to send the POST request in swift 3. Any one please suggest me the correct syntax for URLSession.shared method in swift 3. this is what i tried. iam new here.
let task = URLSession.shared.dataTask(with: request, completionHandler: {
(data, response, error) in
if error != nil{
print("error");
return
}
do{
let myjson = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
if let parsejson = myjson{
var msg: String!
msg = parsejson["message"] as! String?
print(msg)
}catch error {
print ("")
}
}
})
task.resume().
Here's working URLSession.shared code. I don't have your URL so I used one that is online, free, and produces JSON:
let someURL = URL(string:"https://jsonplaceholder.typicode.com/posts/2")!
let request = URLRequest(url: someURL)
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
if error != nil {
print("error")
return
}
guard let data = data else {
print("No data")
return
}
do {
if let myjson = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? Dictionary<String,Any> {
if let title = myjson["title"] {
print("Title was \"\(title)\"")
}
}
} catch {
print("Error parsing JSON: \(error)")
}
}
task.resume()
This outputs Title was "qui est esse" for me.
I have this code snippet here:
let endpointURL = URL(string: "http://foobar.com")
let downloadTask = URLSession.shared.downloadTask(with: endpointURL!, completionHandler: { url, response, error in
if (error == nil) {
let dataObject = NSData(contentsOfURL: endpointURL!)
let jsonArray: Array = JSONSerialization.JSONObjectWithData(dataObject!, options: nil, error: nil) as Array
}
})
downloadTask.resume()
And I'm having this issue:
Ambiguous use of 'init(contentsOfURL:)' for NSData part
How can I make it unambiguous?
I recommend to use something like this in Swift 3, to load JSON data dataTask is more appropriate than downloadTask.
let endpointURL = URL(string: "http://foobar.com")
let dataTask = URLSession.shared.dataTask(with: endpointURL!) { data, response, error in
guard error == nil else {
print(error!)
return
}
do {
// the assumed result type is `[[String:Any]]` cast it to the expected type
if let jsonArray = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]] {
print(jsonArray)
}
} catch {
print(error)
}
}
dataTask.resume()
Can't access json object which is array inside json object
i want to access data from json object which have array inside array
and that json file is also uploaded
so pls can anyone check and help me how to get "weather.description"
data
override func viewDidLoad() {
super.viewDidLoad()
let url = URL(string: "http://api.openweathermap.org/data/2.5/weather?q=London,uk&appid=13ae70c6aefa867c44962edc13f94404")!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if error != nil {
print("some error occured")
} else {
if let urlContent = data {
do{
let jsonResult = try JSONSerialization.jsonObject(with: urlContent, options: JSONSerialization.ReadingOptions.mutableContainers)
let newValue = jsonResult as! NSDictionary
print(jsonResult)
let name = newValue["name"]
//Here i am getting name as variable value
//this is not working
let description = newValue["weather"]??[0]["description"]
//this is not working
let description = newValue["weather"]!![0]["description"]
print()
}catch {
print("JSON Preocessing failed")
}
}
}
}
task.resume()
}
I have edited your code a bit, and added a few comments. Basiclly, lets check for the types of your response structure, and get the desired value.
let url = URL(string: "http://api.openweathermap.org/data/2.5/weather?q=London,uk&appid=13ae70c6aefa867c44962edc13f94404")!
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if error != nil {
print("some error occured")
} else {
if let urlContent = data {
do{
let jsonResult = try JSONSerialization.jsonObject(with: urlContent, options: JSONSerialization.ReadingOptions.mutableContainers)
// I would not recommend to use NSDictionary, try using Swift types instead
guard let newValue = jsonResult as? [String: Any] else {
print("invalid format")
return
}
// Check for the weather parameter as an array of dictionaries and than excess the first array's description
if let weather = newValue["weather"] as? [[String: Any]], let description = weather.first?["description"] as? String {
print(description)
}
}catch {
print("JSON Preocessing failed")
}
}
}
}
task.resume()
I need to use data from a JSON web service to update controls in a SWIFT app. I can get the data no problem, but I can't seem to access the UI controls from within the task block and I can't get the JSON to persist out of the block. I've searched around and haven't found the answer. Here's my test code. The current result is that value1Result has a value inside task, but is nil outside. Thanks in advance.
var jsonResult:NSDictionary!
var value1Result:String!
let task = NSURLSession.sharedSession().dataTaskWithURL(url!) { data, response, error in
var error: NSError?
jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.AllowFragments, error: &error)!
as! Dictionary<String, AnyObject>
println(jsonResult)
if let value1 = jsonResult["value1"] {
println(value1)
value1Result = value1 as! String
}
}
task.resume()
self.textView1.text = value1Result
You can use asynchronous block to update the main UI
dispatch_async(dispatch_get_main_queue()) {
//Update your UI
}
With your code
let task = NSURLSession.sharedSession().dataTaskWithURL(url!) { data, response, error in
var error: NSError?
jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.AllowFragments, error: &error)!
as! Dictionary<String, AnyObject>
println(jsonResult)
if let value1 = jsonResult["value1"] {
println(value1)
dispatch_async(dispatch_get_main_queue()) {
//Update your UI
value1Result = value1 as! String
self.yourtextview.text = value1 as! String
}
}
}
task.resume()
Doing proper network coding is hard. There's a lot of problems with your code both stylistically, in terms of robustness, and actual functionality. That is why networking vs. UI is always layered with a library like AFNetworking. Doing it right yourself is just too much manual labor.
Consider what it takes to check for errors properly and hand off the code properly to the UI thread:
let task = session.dataTaskWithURL(url) {
[unowned self]
(data: NSData?, response: NSURLResponse?, netError: NSError?) in
if let statusCode = (response as? NSHTTPURLResponse)?.statusCode {
if statusCode == 200 {
if let jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: .AllowFragments, error: &error) as? Dictionary<String, AnyObject> {
if let value1 = jsonResult["value1"] as? String {
dispatch_async(dispatch_get_main_queue()) {
self.textView1.text = value1
}
}
else {
println("JSON format error, key value1 not defined")
}
}
else {
println("JSON parsing error: \(error.localizedDescription)")
}
else { // status code other than 200
println("HTTP Error \(statusCode)")
}
}
else { // No HTTP response available at all, couldn't hit server
println("Network Error: \(netErr!.localizedDescription)")
}
}
task.resume()
I cannot figure out how to solve this issue.
This comes from a youtube tutorial to build a simple Weather App.
The tutorial was uploaded in March 2015 and therefor written in a previous version of Swift, there it worked, with the current Swift 2 it doesn't.
The error I get is: "cannot invoke 'jsonObjectWithData' with an argument list of type '(NSData, options: nil, error: NSError)'"
func getWeatherData(urlString:String) {
let url = NSURL(string: urlString)
let task = NSURLSession.sharedSession().dataTaskWithURL(url!){ (data, response, error) in
dispatch_async(dispatch_get_main_queue(), {
self.setLabels(data)
})
}
task.resume()
}
func setLabels(weatherData: NSData) {
var jsonError: NSError
let json = NSJSONSerialization.JSONObjectWithData(weatherData, options: nil, error: jsonError)
if let name = json["name"] as? String {
self.ResultLabel.text = name
}
}
if you want to get this code ready for Swift 2, you have to run the JSONParser with try and catch possible errors.
private func httpGetRequest(request: NSURLRequest!, callback: (NSData?, String?) -> Void) {
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request){
(data, response, error) -> Void in
if error != nil {
callback(nil, error!.localizedDescription)
} else {
callback(data, nil)
}
}
task!.resume()
}
func setLabels(weatherData: NSData) {
do {
let json = try NSJSONSerialization.JSONObjectWithData(weatherData, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if let name = json["name"] as? String {
self.resultLabel.text = name
}
} catch {
print(error)
self.resultLabel.text = "Lorem Ipsum"
}
}
func loadWeatherData() {
let weatherRequest = NSMutableURLRequest(URL: NSURL(string: "Your URL String goes here")!)
httpGetRequest(weatherRequest){
(data, error) -> Void in
if error != nil {
print("Error: \(error)")
} else {
self.setLabels(data!)
}
}
}
Hope that will help to solve your Problems.
Try this:
var jsonError: NSError?
let json = NSJSONSerialization.JSONObjectWithData(weatherData, options: nil, error: &jsonError)
in swift 3.0 and Swift 4.2
try this ...
do {
let jsonData = try JSONSerialization.data(withJSONObject: your array or dictionary, options: JSONSerialization.WritingOptions()) as Data
let json = try JSONSerialization.jsonObject(with: jsonData as Data, options: JSONSerialization.ReadingOptions(rawValue: UInt(0)))
}
catch
{
}
You need to pass the error pointer into NSJSONSerialization.JSONObjectWithData(...) with &.
let json = NSJSONSerialization.JSONObjectWithData(weatherData, options: nil, error: &jsonError) // &jsonError points to the NSErrorPointer of the NSError object
In swift 3 you can try this:
func setLabels(weatherData: NSData) {
do {
var jsonError: NSError
let json = try JSONSerialization.jsonObject(with: weatherData as Data, options: []) as! NSDictionary
if let name = json["name"] as? String {
self.ResultLabel.text = name
}
} catch {
}
}
In Swift 3, you can fix the same error with the code below:
do{
let jsonData = try JSONSerialization.jsonObject(with: (data)!, options: JSONSerialization.ReadingOptions.mutableContainers) as! [String: AnyObject]
}catch{
print("Error while parsing JSON: Handle it")
}