Not able to decode a json answer in swift - json

I try to decode a json answer from a camera. But the camera is answering keys with null (this depends on the camera type).
The result string looks like that:
let string = "{\"id\":1,\"result\":[{\"names\":[\"getAvailableApiList\",\"getShootMode\",\"getSupportedShootMode\",\"getAvailableShootMode\",\"setFlashMode\",\"getFlashMode\",\"getSupportedFlashMode\",\"getAvailableFlashMode\",\"setSelfTimer\",\"getSelfTimer\",\"getSupportedSelfTimer\",\"getAvailableSelfTimer\",\"getSupportedMovieQuality\",\"startLiveview\",\"stopLiveview\",\"actTakePicture\",\"startMovieRec\",\"stopMovieRec\",\"awaitTakePicture\",\"getExposureMode\",\"getSupportedExposureMode\",\"getAvailableExposureMode\",\"setExposureCompensation\",\"getExposureCompensation\",\"getSupportedExposureCompensation\",\"getAvailableExposureCompensation\",\"setFNumber\",\"getFNumber\",\"getSupportedFNumber\",\"getAvailableFNumber\",\"setWhiteBalance\",\"getWhiteBalance\",\"getSupportedWhiteBalance\",\"getAvailableWhiteBalance\",\"getShutterSpeed\",\"getSupportedShutterSpeed\",\"getAvailableShutterSpeed\",\"setIsoSpeedRate\",\"getIsoSpeedRate\",\"getSupportedIsoSpeedRate\",\"getAvailableIsoSpeedRate\",\"actHalfPressShutter\",\"cancelHalfPressShutter\",\"getSupportedProgramShift\",\"getSupportedMovieFileFormat\",\"setContShootingMode\",\"getContShootingMode\",\"getSupportedContShootingMode\",\"getAvailableContShootingMode\",\"setWirelessFlashSetting\",\"getWirelessFlashSetting\",\"getSupportedWirelessFlashSetting\",\"getAvailableWirelessFlashSetting\",\"getApplicationInfo\",\"getEvent\",\"getTemporarilyUnavailableApiList\"],\"type\":\"availableApiList\"},{\"cameraStatus\":\"IDLE\",\"type\":\"cameraStatus\"},null,{\"liveviewStatus\":true,\"type\":\"liveviewStatus\"},null,[],[{\"continuousError\":\"Overheating Warning\",\"isContinued\":false,\"type\":\"continuousError\"},{\"continuousError\":\"Remote Control Not Currently Available\",\"isContinued\":false,\"type\":\"continuousdfError\"}],null,null,null,[],null,null,null,null,null,null,null,{\"currentExposureMode\":\"Aperture\",\"exposureModeCandidates\":[],\"type\":\"exposureMode\"},null,{\"currentSelfTimer\":0,\"selfTimerCandidates\":[0,2,5,10],\"type\":\"selfTimer\"},{\"currentShootMode\":\"still\",\"shootModeCandidates\":[\"still\",\"movie\",\"slow and quick\"],\"type\":\"shootMode\"},null,null,null,{\"currentExposureCompensation\":0,\"maxExposureCompensation\":15,\"minExposureCompensation\":-15,\"stepIndexOfExposureCompensation\":1,\"type\":\"exposureCompensation\"},{\"currentFlashMode\":\"on\",\"flashModeCandidates\":[\"on\",\"rearSync\",\"slowSync\"],\"type\":\"flashMode\"},{\"currentFNumber\":\"3.5\",\"fNumberCandidates\":[\"3.5\",\"4.0\",\"4.5\",\"5.0\",\"5.6\",\"6.3\",\"7.1\",\"8.0\",\"9.0\",\"10\",\"11\",\"13\",\"14\",\"16\",\"18\",\"20\",\"22\"],\"type\":\"fNumber\"},null,{\"currentIsoSpeedRate\":\"250\",\"isoSpeedRateCandidates\":[\"AUTO\",\"50\",\"64\",\"80\",\"100\",\"125\",\"160\",\"200\",\"250\",\"320\",\"400\",\"500\",\"640\",\"800\",\"1000\",\"1250\",\"1600\",\"2000\",\"2500\",\"3200\",\"4000\",\"5000\",\"6400\",\"8000\",\"10000\",\"12800\",\"16000\",\"20000\",\"25600\",\"32000\",\"40000\",\"51200\",\"64000\",\"80000\",\"102400\",\"128000\",\"160000\",\"204800\"],\"type\":\"isoSpeedRate\"},null,null,{\"currentShutterSpeed\":\"1/100\",\"shutterSpeedCandidates\":[],\"type\":\"shutterSpeed\"},{\"checkAvailability\":true,\"currentColorTemperature\":-1,\"currentWhiteBalanceMode\":\"Auto WB\",\"type\":\"whiteBalance\"},null,{\"focusStatus\":\"Not Focusing\",\"type\":\"focusStatus\"},null,null,{\"candidate\":[\"Single\",\"Continuous\"],\"contShootingMode\":\"Single\",\"type\":\"contShootingMode\"},null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null]}"
What is the best way to decode a json answer like that?


Use JSONSerialization and cast result to a dictionary of type [String: Any]
let data = string.data(using: .utf8)!
do {
let result = try JSONSerialization.jsonObject(with: data) as! [String: Any]
//extract info from result
if let array = result["result"] as? [Any] {
let item = array.filter( {
if let dict = $0 as? [String: Any] {
return dict.contains(where: { $0.key == "currentShootMode"})
}
return false
})
print(item)
}
} catch {
print(error)
}
to extract info from the item variable you need to cast again
if let mode = item.first as? [String: Any], let value = mode["currentShootMode"] {
print(value)
}

Related

how to get particular json value in swift

I want the size value in json object but the problem is I'm getting whole json data i want only size value to print
here is my json
[{
size = {
height = 20
width = 10
},
number = 100
}]
here is my code
do{
let Json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers)
//print(Json as Any)
guard let newValue = Json as? [[String: Any]] else {
print("invalid format")
return
}
print(newValue)
}catch {
print("Response Not Found.")
}

Please learn to read JSON, it's pretty easy, there are only two collection types:
[] is array, Swift [Any] but in almost all cases [[String:Any]], accessed with index subscription.
{} is dictionary, Swift [String:Any], accessed with key subscription
Never use the mutableContainers option in Swift, it has no effect at all.
if let json = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]] {
for item in json {
if let size = item["size"] as? [String:Any] {
print(size["height"], size["width"])
}
}
}
And variable names are supposed to start with a lowercase letter.
PS: You have to cast the type of height and width. The output – which is actually not JSON – is ambiguous, you cannot see if the value is String or Int

You just need to extract size from newValue . Try this
do {
let Json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers)
guard let newValue = Json as? [[String: Any]],
let size = newValue[0]["size"] as? [String:Any] else {
return
}
print(size)
}
catch {
print("Response Not Found.")
}

guard let newValue = Json as? [[String: Any]] else {
print("invalid format")
return
}
print(newValue["size"])
or if you want height & width
var sizeDict = newValue["size"] as! [String:Any]
print("Width - \(sizeDict["width"])")
print("Width - \(sizeDict["height"])")

Parsing string json in swift 3

I have a json saved in String format and I´m trying to use:
let json = "{'result':[{'name':'Bob','age':'27'}]}";
Using JSONSerialization comes error about Cannot invoke jsonOject with an argument...
if let json = try JSONSerialization.jsonObject(with: json) as? [String: Any],
let array = json["result"] as? [[String: Any]] {
for item in array {
if let name = item["name"] as? String {
if name == "Bob" {
self.age = Int((item["age"] as? String)!)!
}
}
}
}
I tryed to use this solution but with no success.

Please look at the declaration of jsonObject(with) by ⌥-click on the symbol.
The first parameter is of type Data so you have to convert String to Data.
A major issue is that the JSON is not formatted correctly. The string indicators must be double quotes.
let json = "{\"result\":[{\"name\":\"Bob\",\"age\":27}]}"
let jsonData = json.data(using: .utf8)
do {
if let result = try JSONSerialization.jsonObject(with: jsonData!) as? [String: Any],
...
self.age = item["age"] as! Int

Error while parsing JSON in Swift, [String:Any] won't work

I'm trying to parse this JSON in Swift 3, but it crashes.
Here's the code
do{
let data1: Data = try! Data(contentsOf: NSURL(string: "https://gist.githubusercontent.com/DesWurstes/00baf946bd6d27e7e9355bd6e9969230/raw/a0de898faea8ddedb11b0db516967d0666255633/gist.json") as! URL)
let jsono = try JSONSerialization.jsonObject(with: data1, options: []) as! [String: Any]
}catch{
// catch isn't used here.
}
Here's the error I get when it crashes:
Could not cast value of type '__NSArrayI' (0x7fffe9cb9c08) to 'NSDictionary' (0x7fffe9cba158).
It crashes because not all of the elements of the array are string. (The root of the JSON is an array.)
To prevent it from crashing, changing the third line with this will be suitable:
let jsono = try JSONSerialization.jsonObject(with: data1, options: [])
But then, its type will be Any and I won't be able to parse it with
let string = jsono["something"] as! [String: Any] // Type "Any" has no subscript members
and this code won't run:
if let array = jsono as? [String: Any] {
print("test") // Doesn't print
}
While trying to fix error in the first code, I thought this code may work (Because it says can't convert Array to Dictionary):
let jsono = try JSONSerialization.jsonObject(with: data1, options: []) as! [String]
but it results...
Could not cast value of type '__NSDictionaryI' (0x7fffe9cba108) to 'NSString' (0x7fffea072f38).
Then how can I parse this JSON?

It looks like the JSON response returned from server is an array containing dictionaries of type [String: Any] so you can do:
if let array = jsono as? [[String: Any]] {
print("test") // Will print
for dictionary in array {
print(dictionary["url"] as! String)
}
}
Here you can download the playground I've written to test it out.

you have parse array response so you need to type cast json as? [[String: Any]]..
if your response is dictonary then you need to parse like json as? [String: Any]

func Callservice()
{
let jsonUrlString = "url"
guard let url = URL(string: jsonUrlString) else { return }
URLSession.shared.dataTask(with: url) { (data, response, err) in
guard let data = data else { return }
do {
let courses = try JSONDecoder().decode([Course].self, from: data)
self.arrayData = courses
print(courses)
} catch let jsonErr {
print("Error serializing json:", jsonErr)
}
}.resume()
}
struct course:decodable{
let name:string?
}

"Expression Implicity Coerced from 'String?' to Any" JSON Swift 3

Hi I have the below JSON code I would like to parse
"data":{
"date":"November 30th, 2016",
"personality":"Larry",
"comment":"Saw the homie today"
},
I'm doing this in my viewDidLoad
let url=URL(string:"http://IP-ADDRESS/info.php")
do {
let allNotificationsData = try Data(contentsOf: url!)
let allNotication = try JSONSerialization.jsonObject(with: allNotificationsData, options: JSONSerialization.ReadingOptions.allowFragments) as! [String : AnyObject]
if let arrJSON = allNotication["notifications"] {
for index in 0...arrJSON.count-1 {
let aObject = arrJSON[index] as? [String: AnyObject]
//let name = aObject?["data"]!
if let jsonResponse = aObject,
let info = jsonResponse["data"] {
// Makes sense to check if count > 0 if you're not sure, but...
let transaction_id: String? = info["personality"] as? String
print(transaction_id)
// Do whatever else you need here
}
Which seems to be fine but console returns below. Not sure while "nil" but I just want it show me "date" in the JSON file itself only in the console. Eventually I'll need it to catch an array of dates, not sure how I'll do that but I'm working on it. Let me know if you know what I'm doing wrong. It has to be something with optional.

Assuming the parent object of data is an array (your code suggests that) you can get all data objects in an array with:
do {
let allNotificationsData = try Data(contentsOf: url!)
let allNotification = try JSONSerialization.jsonObject(with: allNotificationsData, options: JSONSerialization.ReadingOptions.allowFragments) as! [String:Any]
if let arrJSON = allNotification["notifications"] as? [[String:Any]] {
let infoArray = arrJSON.flatMap { $0["data"] }
}
...
}
The benefit of flatMap is it ignores nil values.
If you want to access the comment value of the first item in the array write
let comment = (infoArray[0] as! [String:Any])["comment"] as! String

Strange behaviour of optionals in Swift 3

I have experienced a strange behaviour when parsing JSON data using Swift 3.
do {
let json = try JSONSerialization.jsonObject(with: data!, options: []) as! NSDictionary
let items:[AnyObject] = (json["items"] as? [AnyObject])!
for item in items {
let id:String = item["id"] as! String
print("ID: \(id)")
let info = item["volumeInfo"] as AnyObject
print(info)
let title = info["title"]
print(title)
}
} catch {
print("error thrown")
}
This produces the following output. Notice that info is an optional but if I try to unwrap it it states it is not an optional! The script crashes on let title = info["title"] As a result I can't access the title key. This behaviour has changed since Swift 2.
ID: lbvUD6LUyV8C
Optional({
publishedDate = 2002;
publisher = "Sams Publishing";
title = "Java Deployment with JNLP and WebStart";
})

You can do something like:
do {
let json = try JSONSerialization.jsonObject(with: data!) as! [String: Any]
let items = json["items"] as! [[String: Any]]
for item in items {
let id = item["id"] as! String
let info = item["volumeInfo"] as! [String: Any]
let title = info["title"] as! String
print(id)
print(info)
print(title)
}
} catch {
print("error thrown: \(error)")
}
I might suggest excising the code of the ! forced unwrapping (if the JSON was not in the form you expected, do you really want this to crash?), but hopefully this illustrates the basic idea.

The runtime type of info is Optional<Something>, but the compile time type (as you explicitly cast it) is AnyObject. How is the compiler supposed to know that the AnyObject will happen to be an Optional<Something> unless you tell it (in the form of a cast)?
Try:
let info = item["volumeInfo"] as AnyObject?
Now the compiler knows it's an Optional<AnyObject>, so you can unwrap it.

In Swift 3 the compiler must know the types of all subscripted objects if it's an array or dictionary. AnyObject – which has been changed to Any in Swift 3 – is not sufficient.
Since you know that the value for key volumeInfo is a dictionary cast it accordingly preferably using optional bindings
let info = item["volumeInfo"] as? [String:Any] {
print(info)
let title = info["title"] as! String
print(title)
}

This should do:
guard let json = try? JSONSerialization.jsonObject(with: data!, options: []) as! [String: AnyObject],
let items = json["items"] as! Array<AnyObject>? else {
return
}
for item in items {
let id = item["id"] as! String
if let info = item["volumeInfo"] as? [String: AnyObject] {
let title = info["title"] as! String
} else {
// do something
}
}