I am trying to convert an image into data and then that data into a string using this code but it fail on conversion when i want to convert data into string
let data = UIImagePNGRepresentation(selectedImageImageView.image!)
let datastring = String(data: data!, encoding: .utf8)
it gives some in data, but always nil in datastring
cant figure it out where the problem is if anyone knows please help... thanks
if let img = selectedImageImageView.image {
if let data = UIImagePNGRepresentation(img) {
if let datastring = data.base64EncodedStringWithOptions(.Encoding64CharacterLineLength) {
println(datastring)
}
}
}
I try to convert JSON string to a JSON object but after JSONSerialization the output is nil in JSON.
Response String:
[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]
I try to convert this string with my code below:
let jsonString = response.result.value
let data: Data? = jsonString?.data(using: .utf8)
let json = (try? JSONSerialization.jsonObject(with: data, options: [])) as? [String:AnyObject]
print(json ?? "Empty Data")
The problem is that you thought your jsonString is a dictionary. It's not.
It's an array of dictionaries.
In raw json strings, arrays begin with [ and dictionaries begin with {.
I used your json string with below code :
let string = "[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]"
let data = string.data(using: .utf8)!
do {
if let jsonArray = try JSONSerialization.jsonObject(with: data, options : .allowFragments) as? [Dictionary<String,Any>]
{
print(jsonArray) // use the json here
} else {
print("bad json")
}
} catch let error as NSError {
print(error)
}
and I am getting the output :
[["form_desc": <null>, "form_name": Activity 4 with Images, "canonical_name": df_SAWERQ, "form_id": 3465]]
Using JSONSerialization always felt unSwifty and unwieldy, but it is even more so with the arrival of Codable in Swift 4. If you wield a [String:Any] in front of a simple struct it will ... hurt. Check out this in a Playground:
import Cocoa
let data = "[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]".data(using: .utf8)!
struct Form: Codable {
let id: Int
let name: String
let description: String?
private enum CodingKeys: String, CodingKey {
case id = "form_id"
case name = "form_name"
case description = "form_desc"
}
}
do {
let f = try JSONDecoder().decode([Form].self, from: data)
print(f)
print(f[0])
} catch {
print(error)
}
With minimal effort handling this will feel a whole lot more comfortable. And you are given a lot more information if your JSON does not parse properly.
I tried the solutions here, and as? [String:AnyObject] worked for me:
do{
if let json = stringToParse.data(using: String.Encoding.utf8){
if let jsonData = try JSONSerialization.jsonObject(with: json, options: .allowFragments) as? [String:AnyObject]{
let id = jsonData["id"] as! String
...
}
}
}catch {
print(error.localizedDescription)
}
I used below code and it's working fine for me. :
let jsonText = "{\"userName\":\"Bhavsang\"}"
var dictonary:NSDictionary?
if let data = jsonText.dataUsingEncoding(NSUTF8StringEncoding) {
do {
dictonary = try NSJSONSerialization.JSONObjectWithData(data, options: [.allowFragments]) as? [String:AnyObject]
if let myDictionary = dictonary
{
print(" User name is: \(myDictionary["userName"]!)")
}
} catch let error as NSError {
print(error)
}
}
static func getJSONStringFromObject(object: Any?) -> String? {
do {
let jsonData = try JSONSerialization.data(withJSONObject: object ?? DUMMY_STRING, options: [])
return String(data: jsonData, encoding: .utf8) ?? DUMMY_STRING
} catch {
print(error.localizedDescription)
}
return DUMMY_STRING
}
I'm trying to encode and decode Emojis to send them to my database.
I use this to encode:
var comentario = String()
let data = Comment.data(using: String.Encoding.nonLossyASCII, allowLossyConversion: true)
if let data = data {
let emojiString = NSString(data: data, encoding: String.Encoding.utf8.rawValue)! as String
comentario = emojiString
}
And it works. But now I don't know how to decode the emoji.
This is the type of encode ---> \ud83d\ude1a
Your encoding code can be simplified to
func encode(_ s: String) -> String {
let data = s.data(using: .nonLossyASCII, allowLossyConversion: true)!
return String(data: data, encoding: .utf8)!
}
Note that it encodes all non-ASCII characters as \uNNNN, not only
Emojis. Decoding is done by reversing the transformations:
func decode(_ s: String) -> String? {
let data = s.data(using: .utf8)!
return String(data: data, encoding: .nonLossyASCII)
}
This returns an optional because it can fail for invalid input.
Example:
let s = "Hello 😃."
let e = encode(s)
print(e) // Hello \ud83d\ude03.
if let d = decode(e) {
print(d) // Hello 😃.
}
Of course you can also define the code as extension methods of the
String type, and you might want to choose better function names.
I fixed this. If you have a server with encode utf8mb4, then for encoding emojis use this code:
var comentario = String()
let data = Comment.data(using: String.Encoding.nonLossyASCII, allowLossyConversion: true)
if let data = data {
let emojiString = NSString(data: data, encoding: String.Encoding.utf8.rawValue)! as String
comentario = emojiString
}// comentario contains the emoji encoded
DECODING:
let data = comentarios.data(using: String.Encoding.utf8, allowLossyConversion: false)
if data != nil{
let valueunicode = NSString(data: data!, encoding: String.Encoding.nonLossyASCII.rawValue) as? String
if valueunicode != nil{
comentarios = valueunicode!
}
}//comentarios contantes the deecode string(emoji)
This is how I create Data from UIImage:
let data = UIImagePNGRepresentation(image)
And then I need to convert it to String;
if let data = data {
let stringFromData = String(data: data, encoding: .utf8)
}
but stringFromData is nil. Why?
You can get it using the Data method base64EncodedString()
if let data = data {
let stringFromData = data.base64EncodedString()
// to decode base 64 string you can use Data base64Encoded String initializer
if let dataFromBase64 = Data(base64Encoded: stringFromData) {
print(data)
}
}
Convert Your image data in Base64 string
For Encode
let stringFromData : Data = Data(base64Encoded: strBase64, options: .ignoreUnknownCharacters)!
And decode
let strBase64 = imageData.base64EncodedStringWithOptions(.allZeros)
How do you convert an array to a JSON string in swift?
Basically I have a textfield with a button embedded in it.
When button is pressed, the textfield text is added unto the testArray.
Furthermore, I want to convert this array to a JSON string.
This is what I have tried:
func addButtonPressed() {
if goalsTextField.text == "" {
// Do nothing
} else {
testArray.append(goalsTextField.text)
goalsTableView.reloadData()
saveDatatoDictionary()
}
}
func saveDatatoDictionary() {
data = NSKeyedArchiver.archivedDataWithRootObject(testArray)
newData = NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions(), error: nil) as? NSData
string = NSString(data: newData!, encoding: NSUTF8StringEncoding)
println(string)
}
I would also like to return the JSON string using my savetoDictionart() method.
As it stands you're converting it to data, then attempting to convert the data to to an object as JSON (which fails, it's not JSON) and converting that to a string, basically you have a bunch of meaningless transformations.
As long as the array contains only JSON encodable values (string, number, dictionary, array, nil) you can just use NSJSONSerialization to do it.
Instead just do the array->data->string parts:
Swift 3/4
let array = [ "one", "two" ]
func json(from object:Any) -> String? {
guard let data = try? JSONSerialization.data(withJSONObject: object, options: []) else {
return nil
}
return String(data: data, encoding: String.Encoding.utf8)
}
print("\(json(from:array as Any))")
Original Answer
let array = [ "one", "two" ]
let data = NSJSONSerialization.dataWithJSONObject(array, options: nil, error: nil)
let string = NSString(data: data!, encoding: NSUTF8StringEncoding)
although you should probably not use forced unwrapping, it gives you the right starting point.
Swift 3.0 - 4.0 version
do {
//Convert to Data
let jsonData = try JSONSerialization.data(withJSONObject: dictionaryOrArray, options: JSONSerialization.WritingOptions.prettyPrinted)
//Convert back to string. Usually only do this for debugging
if let JSONString = String(data: jsonData, encoding: String.Encoding.utf8) {
print(JSONString)
}
//In production, you usually want to try and cast as the root data structure. Here we are casting as a dictionary. If the root object is an array cast as [Any].
var json = try JSONSerialization.jsonObject(with: jsonData, options: JSONSerialization.ReadingOptions.mutableContainers) as? [String: Any]
} catch {
print(error.description)
}
The JSONSerialization.WritingOptions.prettyPrinted option gives it to the eventual consumer in an easier to read format if they were to print it out in the debugger.
Reference: Apple Documentation
The JSONSerialization.ReadingOptions.mutableContainers option lets you mutate the returned array's and/or dictionaries.
Reference for all ReadingOptions: Apple Documentation
NOTE: Swift 4 has the ability to encode and decode your objects using a new protocol. Here is Apples Documentation, and a quick tutorial for a starting example.
If you're already using SwiftyJSON:
https://github.com/SwiftyJSON/SwiftyJSON
You can do this:
// this works with dictionaries too
let paramsDictionary = [
"title": "foo",
"description": "bar"
]
let paramsArray = [ "one", "two" ]
let paramsJSON = JSON(paramsArray)
let paramsString = paramsJSON.rawString(encoding: NSUTF8StringEncoding, options: nil)
SWIFT 3 UPDATE
let paramsJSON = JSON(paramsArray)
let paramsString = paramsJSON.rawString(String.Encoding.utf8, options: JSONSerialization.WritingOptions.prettyPrinted)!
JSON strings, which are good for transport, don't come up often because you can JSON encode an HTTP body. But one potential use-case for JSON stringify is Multipart Post, which AlamoFire nows supports.
How to convert array to json String in swift 2.3
var yourString : String = ""
do
{
if let postData : NSData = try NSJSONSerialization.dataWithJSONObject(yourArray, options: NSJSONWritingOptions.PrettyPrinted)
{
yourString = NSString(data: postData, encoding: NSUTF8StringEncoding)! as String
}
}
catch
{
print(error)
}
And now you can use yourSting as JSON string..
Swift 5
This generic extension will convert an array of objects to a JSON string from which it can either be:
saved to the App's Documents Directory (iOS/MacOS)
output directly to a file on the Desktop (MacOS)
.
extension JSONEncoder {
static func encode<T: Encodable>(from data: T) {
do {
let jsonEncoder = JSONEncoder()
jsonEncoder.outputFormatting = .prettyPrinted
let json = try jsonEncoder.encode(data)
let jsonString = String(data: json, encoding: .utf8)
// iOS/Mac: Save to the App's documents directory
saveToDocumentDirectory(jsonString)
// Mac: Output to file on the user's Desktop
saveToDesktop(jsonString)
} catch {
print(error.localizedDescription)
}
}
static private func saveToDocumentDirectory(_ jsonString: String?) {
guard let path = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let fileURL = path.appendingPathComponent("Output.json")
do {
try jsonString?.write(to: fileURL, atomically: true, encoding: .utf8)
} catch {
print(error.localizedDescription)
}
}
static private func saveToDesktop(_ jsonString: String?) {
let homeURL = FileManager.default.homeDirectoryForCurrentUser
let desktopURL = homeURL.appendingPathComponent("Desktop")
let fileURL = desktopURL.appendingPathComponent("Output.json")
do {
try jsonString?.write(to: fileURL, atomically: true, encoding: .utf8)
} catch {
print(error.localizedDescription)
}
}
}
Example:
struct Person: Codable {
var name: String
var pets: [Pet]
}
struct Pet: Codable {
var type: String
}
extension Person {
static func sampleData() -> [Person] {
[
Person(name: "Adam", pets: []),
Person(name: "Jane", pets: [
Pet(type: "Cat")
]),
Person(name: "Robert", pets: [
Pet(type: "Cat"),
Pet(type: "Rabbit")
])
]
}
}
Usage:
JSONEncoder.encode(from: Person.sampleData())
Output:
This will create the following correctly formatted Output.json file:
[
{
"name" : "Adam",
"pets" : [
]
},
{
"name" : "Jane",
"pets" : [
{
"type" : "Cat"
}
]
},
{
"name" : "Robert",
"pets" : [
{
"type" : "Cat"
},
{
"type" : "Rabbit"
}
]
}
]
SWIFT 2.0
var tempJson : NSString = ""
do {
let arrJson = try NSJSONSerialization.dataWithJSONObject(arrInvitationList, options: NSJSONWritingOptions.PrettyPrinted)
let string = NSString(data: arrJson, encoding: NSUTF8StringEncoding)
tempJson = string! as NSString
}catch let error as NSError{
print(error.description)
}
NOTE:- use tempJson variable when you want to use.
extension Array where Element: Encodable {
func asArrayDictionary() throws -> [[String: Any]] {
var data: [[String: Any]] = []
for element in self {
data.append(try element.asDictionary())
}
return data
}
}
extension Encodable {
func asDictionary() throws -> [String: Any] {
let data = try JSONEncoder().encode(self)
guard let dictionary = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any] else {
throw NSError()
}
return dictionary
}
}
If you're using Codable protocols in your models these extensions might be helpful for getting dictionary representation (Swift 4)
Hint: To convert an NSArray containing JSON compatible objects to an NSData object containing a JSON document, use the appropriate method of NSJSONSerialization. JSONObjectWithData is not it.
Hint 2: You rarely want that data as a string; only for debugging purposes.
For Swift 4.2, that code still works fine
var mnemonic: [String] = ["abandon", "amount", "liar", "buyer"]
var myJsonString = ""
do {
let data = try JSONSerialization.data(withJSONObject:mnemonic, options: .prettyPrinted)
myJsonString = NSString(data: data, encoding: String.Encoding.utf8.rawValue) as! String
} catch {
print(error.localizedDescription)
}
return myJsonString
Swift 5
Make sure your object confirm Codable.
Swift's default variable types like Int, String, Double and ..., all are Codable that means we can convert theme to Data and vice versa.
For example, let's convert array of Int to String Base64
let array = [1, 2, 3]
let data = try? JSONEncoder().encode(array)
nsManagedObject.array = data?.base64EncodedString()
Make sure your NSManaged variable type is String in core data schema editor and custom class if your using custom class for core data objects.
let's convert back base64 string to array:
var getArray: [Int] {
guard let array = array else { return [] }
guard let data = Data(base64Encoded: array) else { return [] }
guard let val = try? JSONDecoder().decode([Int].self, from: data) else { return [] }
return val
}
Do not convert your own object to Base64 and store as String in CoreData and vice versa because we have something that named Relation in CoreData (databases).
For Swift 3.0 you have to use this:
var postString = ""
do {
let data = try JSONSerialization.data(withJSONObject: self.arrayNParcel, options: .prettyPrinted)
let string1:String = NSString(data: data, encoding: String.Encoding.utf8.rawValue) as! String
postString = "arrayData=\(string1)&user_id=\(userId)&markupSrcReport=\(markup)"
} catch {
print(error.localizedDescription)
}
request.httpBody = postString.data(using: .utf8)
100% working TESTED
You can try this.
func convertToJSONString(value: AnyObject) -> String? {
if JSONSerialization.isValidJSONObject(value) {
do{
let data = try JSONSerialization.data(withJSONObject: value, options: [])
if let string = NSString(data: data, encoding: String.Encoding.utf8.rawValue) {
return string as String
}
}catch{
}
}
return nil
}