问题
I'm really struggling with trying to read a JSON file into Swift so I can play around with it. I've spent the best part of 2 days re-searching and trying different methods but no luck as of yet so I have signed up to StackOverFlow to see if anyone can point me in the right direction.....
My JSON file is called test.json and contains the following:
{
"person":[
{
"name": "Bob",
"age": "16",
"employed": "No"
},
{
"name": "Vinny",
"age": "56",
"employed": "Yes"
}
]
}
The file is stored in the documents directly and I access it using the following code:
let file = "test.json"
let dirs : String[] = NSSearchPathForDirectoriesInDomains(
NSSearchpathDirectory.DocumentDirectory,
NSSearchPathDomainMask.AllDomainMask,
true) as String[]
if (dirs != nil) {
let directories: String[] = dirs
let dir = directories[0]
let path = dir.stringByAppendingPathComponent(file)
}
var jsonData = NSData(contentsOfFile:path, options: nil, error: nil)
println("jsonData \(jsonData)" // This prints what looks to be JSON encoded data.
var jsonDict = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: nil) as? NSDictionary
println("jsonDict \(jsonDict)") - This prints nil.....
If anyone can just give me a push in the right direction on how I can de-serialize the JSON file and put it in an accessible Swift object I will be eternally grateful!
Kind Regards,
Krivvenz.
回答1:
Follow the below code :
if let path = NSBundle.mainBundle().pathForResource("test", ofType: "json")
{
if let jsonData = NSData(contentsOfFile: path, options: .DataReadingMappedIfSafe, error: nil)
{
if let jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers, error: nil) as? NSDictionary
{
if let persons : NSArray = jsonResult["person"] as? NSArray
{
// Do stuff
}
}
}
}
The array "persons" will contain all data for key person. Iterate throughs to fetch it.
Swift 4.0:
if let path = Bundle.main.path(forResource: "test", ofType: "json") {
do {
let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .mappedIfSafe)
let jsonResult = try JSONSerialization.jsonObject(with: data, options: .mutableLeaves)
if let jsonResult = jsonResult as? Dictionary<String, AnyObject>, let person = jsonResult["person"] as? [Any] {
// do stuff
}
} catch {
// handle error
}
}
回答2:
If anyone is looking for SwiftyJSON Answer:
Update:
For Swift 3/4:
if let path = Bundle.main.path(forResource: "assets/test", ofType: "json") {
do {
let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .alwaysMapped)
let jsonObj = try JSON(data: data)
print("jsonData:\(jsonObj)")
} catch let error {
print("parse error: \(error.localizedDescription)")
}
} else {
print("Invalid filename/path.")
}
回答3:
Swift 4 using Decodable
struct ResponseData: Decodable {
var person: [Person]
}
struct Person : Decodable {
var name: String
var age: String
var employed: String
}
func loadJson(filename fileName: String) -> [Person]? {
if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
do {
let data = try Data(contentsOf: url)
let decoder = JSONDecoder()
let jsonData = try decoder.decode(ResponseData.self, from: data)
return jsonData.person
} catch {
print("error:\(error)")
}
}
return nil
}
Swift 3
func loadJson(filename fileName: String) -> [String: AnyObject]? {
if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
do {
let data = try Data(contentsOf: url)
let object = try JSONSerialization.jsonObject(with: data, options: .allowFragments)
if let dictionary = object as? [String: AnyObject] {
return dictionary
}
} catch {
print("Error!! Unable to parse \(fileName).json")
}
}
return nil
}
回答4:
Xcode 8 Swift 3 read json from file update:
if let path = Bundle.main.path(forResource: "userDatabseFakeData", ofType: "json") {
do {
let jsonData = try NSData(contentsOfFile: path, options: NSData.ReadingOptions.mappedIfSafe)
do {
let jsonResult: NSDictionary = try JSONSerialization.jsonObject(with: jsonData as Data, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary
if let people : [NSDictionary] = jsonResult["person"] as? [NSDictionary] {
for person: NSDictionary in people {
for (name,value) in person {
print("\(name) , \(value)")
}
}
}
} catch {}
} catch {}
}
回答5:
Updated names for Swift 3.0
Based on Abhishek's answer and Druva's answer
func loadJson(forFilename fileName: String) -> NSDictionary? {
if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
if let data = NSData(contentsOf: url) {
do {
let dictionary = try JSONSerialization.jsonObject(with: data as Data, options: .allowFragments) as? NSDictionary
return dictionary
} catch {
print("Error!! Unable to parse \(fileName).json")
}
}
print("Error!! Unable to load \(fileName).json")
}
return nil
}
回答6:
Swift 2.1 answer (based on Abhishek's) :
if let path = NSBundle.mainBundle().pathForResource("test", ofType: "json") {
do {
let jsonData = try NSData(contentsOfFile: path, options: NSDataReadingOptions.DataReadingMappedIfSafe)
do {
let jsonResult: NSDictionary = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if let people : [NSDictionary] = jsonResult["person"] as? [NSDictionary] {
for person: NSDictionary in people {
for (name,value) in person {
print("\(name) , \(value)")
}
}
}
} catch {}
} catch {}
}
回答7:
Swift 3.0, Xcode 8, iOS 10
if let path = Bundle.main.url(forResource: "person", withExtension: "json") {
do {
let jsonData = try Data(contentsOf: path, options: .mappedIfSafe)
do {
if let jsonResult = try JSONSerialization.jsonObject(with: jsonData, options: JSONSerialization.ReadingOptions(rawValue: 0)) as? NSDictionary {
if let personArray = jsonResult.value(forKey: "person") as? NSArray {
for (_, element) in personArray.enumerated() {
if let element = element as? NSDictionary {
let name = element.value(forKey: "name") as! String
let age = element.value(forKey: "age") as! String
let employed = element.value(forKey: "employed") as! String
print("Name: \(name), age: \(age), employed: \(employed)")
}
}
}
}
} catch let error as NSError {
print("Error: \(error)")
}
} catch let error as NSError {
print("Error: \(error)")
}
}
Output:
Name: Bob, age: 16, employed: No
Name: Vinny, age: 56, employed: Yes
回答8:
Simplifying the example provided by Peter Kreinz. Works with Swift 4.2.
The extension function:
extension Decodable {
static func parse(jsonFile: String) -> Self? {
guard let url = Bundle.main.url(forResource: jsonFile, withExtension: "json"),
let data = try? Data(contentsOf: url),
let output = try? JSONDecoder().decode(self, from: data)
else {
return nil
}
return output
}
}
The example model:
struct Service: Decodable {
let name: String
}
The example usage:
/// service.json
/// { "name": "Home & Garden" }
guard let output = Service.parse(jsonFile: "service") else {
// do something if parsing failed
return
}
// use output if all good
The example will work with arrays, too:
/// services.json
/// [ { "name": "Home & Garden" } ]
guard let output = [Service].parse(jsonFile: "services") else {
// do something if parsing failed
return
}
// use output if all good
Notice how we don't provide any unnecessary generics, thus we don't need to cast the result of parse.
回答9:
This worked great with me
func readjson(fileName: String) -> NSData{
let path = NSBundle.mainBundle().pathForResource(fileName, ofType: "json")
let jsonData = NSData(contentsOfMappedFile: path!)
return jsonData!
}
回答10:
Here is my solution using SwiftyJSON
if let path : String = NSBundle.mainBundle().pathForResource("filename", ofType: "json") {
if let data = NSData(contentsOfFile: path) {
let json = JSON(data: data)
}
}
回答11:
fileprivate class BundleTargetingClass {}
func loadJSON<T>(name: String) -> T? {
guard let filePath = Bundle(for: BundleTargetingClass.self).url(forResource: name, withExtension: "json") else {
return nil
}
guard let jsonData = try? Data(contentsOf: filePath, options: .mappedIfSafe) else {
return nil
}
guard let json = try? JSONSerialization.jsonObject(with: jsonData, options: .allowFragments) else {
return nil
}
return json as? T
}
👆🏻 copy-paste ready, 3rd party framework independent solution.
usage 👇🏻
let json:[[String : AnyObject]] = loadJSON(name: "Stations")!
回答12:
I'm providing another answer because none of the ones here are geared toward loading the resource from the test bundle. If you are consuming a remote service that puts out JSON and want to unit test parsing the results without hitting the actual service, you take one or more responses and put them into files in the Tests folder in your project.
func testCanReadTestJSONFile() {
let path = NSBundle(forClass: ForecastIOAdapterTests.self).pathForResource("ForecastIOSample", ofType: "json")
if let jsonData = NSData(contentsOfFile:path!) {
let json = JSON(data: jsonData)
if let currentTemperature = json["currently"]["temperature"].double {
println("json: \(json)")
XCTAssertGreaterThan(currentTemperature, 0)
}
}
}
This also uses SwiftyJSON but the core logic of getting the test bundle and loading the file is the answer to the question.
回答13:
Swift 4: Try out my solution:
test.json
{
"person":[
{
"name": "Bob",
"age": "16",
"employed": "No"
},
{
"name": "Vinny",
"age": "56",
"employed": "Yes"
}
]
}
RequestCodable.swift
import Foundation
struct RequestCodable:Codable {
let person:[PersonCodable]
}
PersonCodable.swift
import Foundation
struct PersonCodable:Codable {
let name:String
let age:String
let employed:String
}
Decodable+FromJSON.swift
import Foundation
extension Decodable {
static func fromJSON<T:Decodable>(_ fileName: String, fileExtension: String="json", bundle: Bundle = .main) throws -> T {
guard let url = bundle.url(forResource: fileName, withExtension: fileExtension) else {
throw NSError(domain: NSURLErrorDomain, code: NSURLErrorResourceUnavailable)
}
let data = try Data(contentsOf: url)
return try JSONDecoder().decode(T.self, from: data)
}
}
Example:
let result = RequestCodable.fromJSON("test") as RequestCodable?
result?.person.compactMap({ print($0) })
/*
PersonCodable(name: "Bob", age: "16", employed: "No")
PersonCodable(name: "Vinny", age: "56", employed: "Yes")
*/
回答14:
Latest swift 3.0 absolutely working
func loadJson(filename fileName: String) -> [String: AnyObject]?
{
if let url = Bundle.main.url(forResource: fileName, withExtension: "json")
{
if let data = NSData(contentsOf: url) {
do {
let object = try JSONSerialization.jsonObject(with: data as Data, options: .allowFragments)
if let dictionary = object as? [String: AnyObject] {
return dictionary
}
} catch {
print("Error!! Unable to parse \(fileName).json")
}
}
print("Error!! Unable to load \(fileName).json")
}
return nil
}
回答15:
Updated for Swift 3 with safest way
private func readLocalJsonFile() {
if let urlPath = Bundle.main.url(forResource: "test", withExtension: "json") {
do {
let jsonData = try Data(contentsOf: urlPath, options: .mappedIfSafe)
if let jsonDict = try JSONSerialization.jsonObject(with: jsonData, options: .mutableContainers) as? [String: AnyObject] {
if let personArray = jsonDict["person"] as? [[String: AnyObject]] {
for personDict in personArray {
for (key, value) in personDict {
print(key, value)
}
print("\n")
}
}
}
}
catch let jsonError {
print(jsonError)
}
}
}
回答16:
Based on Abhishek's answer, for iOS 8 this would be:
let masterDataUrl: NSURL = NSBundle.mainBundle().URLForResource("masterdata", withExtension: "json")!
let jsonData: NSData = NSData(contentsOfURL: masterDataUrl)!
let jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: nil) as! NSDictionary
var persons : NSArray = jsonResult["person"] as! NSArray
回答17:
This worked for me with XCode 8.3.3
func fetchPersons(){
if let pathURL = Bundle.main.url(forResource: "Person", withExtension: "json"){
do {
let jsonData = try Data(contentsOf: pathURL, options: .mappedIfSafe)
let jsonResult = try JSONSerialization.jsonObject(with: jsonData, options: .mutableContainers) as! [String: Any]
if let persons = jsonResult["person"] as? [Any]{
print(persons)
}
}catch(let error){
print (error.localizedDescription)
}
}
}
回答18:
Swift 4.1 Updated Xcode 9.2
if let filePath = Bundle.main.path(forResource: "fileName", ofType: "json"), let data = NSData(contentsOfFile: filePath) {
do {
let json = try JSONSerialization.jsonObject(with: data as Data, options: JSONSerialization.ReadingOptions.allowFragments)
}
catch {
//Handle error
}
}
回答19:
Swift 4 JSON to Class with Decodable - for those who prefer classes
Define the classes as follows:
class People: Decodable {
var person: [Person]?
init(fileName : String){
// url, data and jsonData should not be nil
guard let url = Bundle.main.url(forResource: fileName, withExtension: "json") else { return }
guard let data = try? Data(contentsOf: url) else { return }
guard let jsonData = try? JSONDecoder().decode(People.self, from: data) else { return }
// assigns the value to [person]
person = jsonData.person
}
}
class Person : Decodable {
var name: String
var age: String
var employed: String
}
Usage, pretty abstract:
let people = People(fileName: "people")
let personArray = people.person
This allow methods for both People and Person classes, variables (attributes) and methods can also marked as private if needed.
回答20:
I’ve used below code to fetch JSON from FAQ-data.json file present in project directory .
I’m implementing in Xcode 7.3 using Swift.
func fetchJSONContent() {
if let path = NSBundle.mainBundle().pathForResource("FAQ-data", ofType: "json") {
if let jsonData = NSData(contentsOfFile: path) {
do {
if let jsonResult: NSDictionary = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers) as? NSDictionary {
if let responseParameter : NSDictionary = jsonResult["responseParameter"] as? NSDictionary {
if let response : NSArray = responseParameter["FAQ"] as? NSArray {
responseFAQ = response
print("response FAQ : \(response)")
}
}
}
}
catch { print("Error while parsing: \(error)") }
}
}
}
override func viewWillAppear(animated: Bool) {
fetchFAQContent()
}
Structure of JSON file :
{
"status": "00",
"msg": "FAQ List ",
"responseParameter": {
"FAQ": [
{
"question": “Question No.1 here”,
"answer": “Answer goes here”,
"id": 1
},
{
"question": “Question No.2 here”,
"answer": “Answer goes here”,
"id": 2
}
. . .
]
}
}
回答21:
I might also recommend Ray Wenderlich's Swift JSON Tutorial (which also covers the awesome SwiftyJSON alternative, Gloss). An excerpt (which granted, by itself, does not fully answer the poster, but the added value of this answer is the link, so no -1's for that, please):
In Objective-C, parsing and deserializing JSON is fairly straightforward:
NSArray *json = [NSJSONSerialization JSONObjectWithData:JSONData
options:kNilOptions error:nil];
NSString *age = json[0][@"person"][@"age"];
NSLog(@"Dani's age is %@", age);
In Swift, parsing and deserializing JSON is a little more tedious due to Swift optionals and type-safety [but as] part of Swift 2.0 the
guardstatement was introduced to help get rid of nestedifstatements:
var json: Array!
do {
json = try NSJSONSerialization.JSONObjectWithData(JSONData, options: NSJSONReadingOptions()) as? Array
} catch {
print(error)
}
guard let item = json[0] as? [String: AnyObject],
let person = item["person"] as? [String: AnyObject],
let age = person["age"] as? Int else {
return;
}
print("Dani's age is \(age)")
Of course, in XCode 8.x, you just double-tap the space bar and say "Hey, Siri, please deserialize this JSON for me in Swift 3.0 with space/tab-indents."
回答22:
SWIFTYJSON VERSION SWIFT 3
func loadJson(fileName: String) -> JSON {
var dataPath:JSON!
if let path : String = Bundle.main.path(forResource: fileName, ofType: "json") {
if let data = NSData(contentsOfFile: path) {
dataPath = JSON(data: data as Data)
}
}
return dataPath
}
回答23:
First create a Struc codable like this:
struct JuzgadosList : Codable {
var CP : Int
var TEL : String
var LOCAL : String
var ORGANO : String
var DIR : String
}
Now declare the variable
var jzdosList = [JuzgadosList]()
Read from main directory
func getJsonFromDirectory() {
if let path = Bundle.main.path(forResource: "juzgados", ofType: "json") {
do {
let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .alwaysMapped)
let jList = try JSONDecoder().decode([JuzgadosList].self, from: data)
self.jzdosList = jList
DispatchQueue.main.async() { () -> Void in
self.tableView.reloadData()
}
} catch let error {
print("parse error: \(error.localizedDescription)")
}
} else {
print("Invalid filename/path.")
}
}
Read from web
func getJsonFromUrl(){
self.jzdosList.removeAll(keepingCapacity: false)
print("Internet Connection Available!")
guard let url = URL(string: "yourURL") else { return }
let request = URLRequest(url: url, cachePolicy: URLRequest.CachePolicy.reloadIgnoringLocalCacheData, timeoutInterval: 60.0)
URLSession.shared.dataTask(with: request) { (data, response, err) in
guard let data = data else { return }
do {
let jList = try JSONDecoder().decode([JuzgadosList].self, from: data)
self.jzdosList = jList
DispatchQueue.main.async() { () -> Void in
self.tableView.reloadData()
}
} catch let jsonErr {
print("Error serializing json:", jsonErr)
}
}.resume()
}
回答24:
//change type based on your struct and right JSON file
let quoteData: [DataType] =
load("file.json")
func load<T: Decodable>(_ filename: String, as type: T.Type = T.self) -> T {
let data: Data
guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
else {
fatalError("Couldn't find \(filename) in main bundle.")
}
do {
data = try Data(contentsOf: file)
} catch {
fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
}
do {
let decoder = JSONDecoder()
return try decoder.decode(T.self, from: data)
} catch {
fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
}
}
来源：https://stackoverflow.com/questions/24410881/reading-in-a-json-file-using-swift