I am making http call and receiving JSON response
var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as! NSDictionary
But when not receiving actual json this line fail with error cannot cast value of NSArray to NSDictionary
I understand why this happen my question is how to properly check what format is the response
I do like this in my api's:
typealias JSONType = (dictionary: [String:AnyObject]?, array: [AnyObject]?)
var error:NSError?
var json:AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &error)
if let dict = json as? [String:AnyObject] {
return (dict, nil)
}
else if let arr = json as? [AnyObject] {
return (nil, arr)
}
So when I return that JSONType I can change to use it as a dictionary or array by just:
json.array
Related
when decoding JSON from webservice(API) i get error :
Could not cast value of type '__NSDictionaryM' (0x1037ad8a8) to 'NSArray' (0x1037ad470).
My Code :
var kGetURL = "http://bitnami.local/cscart_demo/api/users"
//var kGetURL = "http://localhost/fendy/getjson.php"
var json : Array<AnyObject> = []
override func viewDidLoad() {
super.viewDidLoad()
start()
}
func getData(data : NSData){
//error at this line :
json = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as! Array<AnyObject>
//error
tableView.reloadData()
}
func start(){
var url : NSURL = NSURL(string: kGetURL)!
var data : NSData = NSData(contentsOfURL: url)!
getData(data)
}
if i change url to http://localhost/fendy/getjson.php, its working so nice.
i get error if my url is http://bitnami.local/cscart_demo/api/users
Response from webservice http://localhost/fendy/getjson.php :
[{"id":"17","Name":"KFC","Message":"awesome"},
{"id":"18","Name":"McDonald","Message":"good"},
{"id":"23","Name":"Burger King","Message":"tasty"},
{"id":"38","Name":"Pizza hut","Message":"yummy"},
{"id":"39","Name":"Steak","Message":"very Delicious"}]
Response from webservice http://bitnami.local/cscart_demo/api/users :
{"users":
[{"user_id":"4","user_login":"user_4","is_root":"N","timestamp":"1441608048","user_type":"C","status":"A","firstname":"","lastname":"","email":"fendy.w#mvig.net","company":"","company_id":"1","company_name":"Simtech"},
{"user_id":"3","user_login":"customer","is_root":"N","timestamp":"1441604240","user_type":"C","status":"A","firstname":"Customer","lastname":"Customer","email":"customer#example.com","company":"Simtech","company_id":"1","company_name":"Simtech"},
{"user_id":"1","user_login":"admin","is_root":"Y","timestamp":"1441604240","user_type":"A","status":"A","firstname":"John","lastname":"Doe","email":"robby#mvig.net","company":"Your company","company_id":"0","company_name":null}],
"params":{"page":1,"items_per_page":"10","sort_order":"asc","sort_by":"name","sort_order_rev":"desc","total_items":"3"}}
i think it's Style is same, but why not working with url http://bitnami.local/cscart_demo/api/users . anyone can help?
The bitnami response starts with a { and it is therefore a JSON object, which corresponds to an NSDictionary. The other one starts with [ which indicates an array.
You need to change the type of json to Dictionary<String, AnyObject>, and deserialize as follows:
json = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as! Dictionary<String, AnyObject>
Your method is casting JSON result to an array. It works fine with the URL that returns an array represented as JSON, but it does not work with the URL that returns a dictionary, not an array, represented as JSON.
Although the "style" of returned values looks the same, the second one is a one-item dictionary. What you probably want is to extract the "users" element from it, which is an array.
If you do not know which of the two URLs you are getting, you could try both styles with as? cast instead of as!:
let tmp : AnyObject! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil)
if let arr = tmp as? Array<AnyObject> {
json = arr
} else if dict = tmp as? [String: AnyObject] {
json = dict["users"] as! Array<AnyObject>
} else {
// Handle an error: the input was unexpected
}
tableView.reloadData()
try cache for Serialization
do {
if let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String : Any] { // as? data type
if let otherDict = json["dataKey"] as? [String : Any] {
//do something
}
}
} catch {
// can't json serialization
}
I am trying to create a dictionary from data that is held in a server, I receive the data but I cannot convert the data to an NSDictionary, I believe it is held in an NSData Object
let JSONDictionary: Dictionary = NSJSONSerialization.JSONObjectWithData(JSONData!, options: nil, error: &error) as NSDictionary
This line of code is the one giving me the problem, it throws a BAD_EXEC_INSTRUCTION.
MY Question: How can I turn a JSON into an NSDictionary?
Your code does not do any error handling. But it can (and if this data comes from a web service, will) fail in multiple ways.
You have to make sure that your data object actually exists
You have to make sure that the data object can be converted to JSON
You have to make sure that the JSON actually contains a Dictionary
You should use Swifts conditional cast and it's optional binding capabilities.
The optional binding if let JSONData = JSONData checks that JSONData is not nil. The force unwrap (JSONData!) you use might crash if no data could be received.
The optional binding if let json = NSJSONSerialization.JSONObjectWithData checks if the data could be converted to a JSON object. The conditional cast as? NSDictionary checks if the JSON object is actually a dictionary. You currently don't use these checks, you cast the objects as NSDictionary. Which will crash, if the object is not valid json, or if its not a dictionary.
I would recommend something like this:
var error: NSError?
if let JSONData = JSONData { // Check 1
if let json: AnyObject = NSJSONSerialization.JSONObjectWithData(JSONData, options: nil, error: &error) { // Check 2
if let jsonDictionary = json as? NSDictionary { // Check 3
println("Dictionary received")
}
else {
if let jsonString = NSString(data: JSONData, encoding: NSUTF8StringEncoding) {
println("JSON String: \n\n \(jsonString)")
}
fatalError("JSON does not contain a dictionary \(json)")
}
}
else {
fatalError("Can't parse JSON \(error)")
}
}
else {
fatalError("JSONData is nil")
}
You could merge check 2 and 3 into one line and check if NSJSONSerialization can create a NSDictionary directly:
var error: NSError?
if let JSONData = JSONData { // Check 1.
if let JSONDictionary = NSJSONSerialization.JSONObjectWithData(JSONData, options: nil, error: &error) as? NSDictionary { // Check 2. and 3.
println("Dictionary received")
}
else {
if let jsonString = NSString(data: JSONData, encoding: NSUTF8StringEncoding) {
println("JSON: \n\n \(jsonString)")
}
fatalError("Can't parse JSON \(error)")
}
}
else {
fatalError("JSONData is nil")
}
Make sure to replace fatalError with appropriate error handling in your production code
Update for Swift 2.
Now you must use it inside a try catch block.
do {
let responseObject = try NSJSONSerialization.JSONObjectWithData(data, options: []) as! [String:AnyObject]
} catch let error as NSError {
print("error: \(error.localizedDescription)")
}
Here jsonResult will give you the response in NSDictionary:
let url = NSURL(string: path)
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithURL(url!, completionHandler: {data, response, error -> Void in
println("Task completed")
if(error != nil) {
// If there is an error in the web request, print it to the console
println(error.localizedDescription)
}
var err: NSError?
var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as NSDictionary
if(err != nil) {
// If there is an error parsing JSON, print it to the console
println("JSON Error \(err!.localizedDescription)")
}
})
task.resume()
I want to parse a json file, this is in my json file:
{
"currentPowerByClient": 0, <- i want to read this
"currentPowerToClient":518,
"tariff":1,
"totalGasDelivered":1061.004,
"totalPowerByClientHigh":10.704,
"totalPowerByClientLow":23.042,
"totalPowerToClientHigh":912.221,
"totalPowerToClientLow": 693.499
}
this is my swift code, the object called JSONResult contains my JSON code
var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options:
NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
if let item = jsonResult as NSDictionary? {
if let currentPowerByClient = item["currentPowerByClient"] as? NSDictionary {
println(currentPowerByClient)
}
}
when i run it, it doesn't print anything
The line
if let currentPowerByClient = item["currentPowerByClient"] as? NSDictionary
should be
if let currentPowerByClient = item["currentPowerByClient"] as? NSNumber
because item["currentPowerByClient"] is expected to be a number, not a dictionary. it works then
I tried to get the value of "seed" from json response. But i am getting nil.
Json Response:
{
"response": {
"params": {
"rows": "20",
"defType": "abc",
"seed": "381786611"
}
}
}
Swift Parsing:
if let responseHeader:AnyObject = object?["response"] as? NSDictionary {
if let t = (responseHeader["params"] as? NSDictionary){
let t1 = t["seed"] as? String
println("result is \(t1)") // This returns nil
}
}
Json Parsing
func processJsonToDictionary(object:AnyObject?) -> AnyObject?{
if object != nil {
if let data: AnyObject = object {
var parseError: NSError?
var jsonResult = NSJSONSerialization.JSONObjectWithData(object as NSData!, options: NSJSONReadingOptions.MutableContainers, error: &parseError) as? NSDictionary
if(parseError != nil){
return parseError
}
else{
return jsonResult
}
}
}
return nil
}
I am not able to get the value of t1. it always returns nil.
How can i get the value.
Also, I put a breakpoint and tried to print the value of t1. But the Xcode Keeps crashing. Why?
I think the major problem here is only accessing a JSON object in swift.
var error: NSError?
let jsonDict = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: &error) as NSDictionary
let resp = jsonDict["response"] as? NSDictionary
let params = resp?["params"]?["seed"]
let seed = params!! as NSString
This is just to show you how a JSON object is accessed in swift. You can ofcourse change it according to your needs to remove unwanted Optional Chaining.
For easy JSON manipulation in Swift you could try this little library. It seems pretty easy and you could do this:
var dictionary: [String: AnyObject]!
if let json = NKJSON.parse(yourNSDataObject) {
dictionary <> json[NKJSON.rootKey]
}
First confirm that the response which you are getting is in json format or in string format.
For json parsing you can use swifty json pod
There code:
var err: NSError
var jsonDict = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as Array<NSDictionary>
If data has JSON it's works perfect. But if there something other (not JSON Array) it's just has fatal error and iOS simulator close with EXC_BAD_INSTRUCTION.
So there no call err. How I can check data before? Or catch the error.
(Sorry, am in a hurry, no description yet.)
var err: NSError?
var jsonDict: AnyObject!
var data: AnyObject = "{ }".dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)
if let d = data as? NSData {
jsonDict = NSJSONSerialization.JSONObjectWithData(d, options: NSJSONReadingOptions.MutableContainers, error: &err)
if let dict = jsonDict as? NSDictionary {
// Do something with `dict`
println(dict)
}
}
This probably happens because JSONObjectWithData is declared to return id, but in reality it returns NSDictionary*, NSArray* or nil - in Swift, assigning nil to a variable of type id crashes by design. You need to give jsonDict a type, probably an optional NSMutableDictionary* or NSMutableArray*.