我真的在努力把一个JSON文件读入Swift，这样我就可以玩它了。我花了2天的时间重新搜索和尝试不同的方法，但没有运气，所以我已经注册了StackOverFlow，看看是否有人能给我指点正确的方向.....
我的JSON文件叫做test。Json，并包含以下内容:
{
"person":[
{
"name": "Bob",
"age": "16",
"employed": "No"
},
{
"name": "Vinny",
"age": "56",
"employed": "Yes"
}
]
}
该文件直接存储在文档中，我使用以下代码访问它:
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.....
如果有人能给我一个正确的方向，我可以反序列化JSON文件，并把它放在一个可访问的Swift对象，我会永远感激!
亲切的问候,
Krivvenz。
我使用下面的代码从FAQ-data中获取JSON。Json文件存在于项目目录中。
我在Xcode 7.3中使用Swift实现。
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()
}
JSON文件结构:
{
"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
}
. . .
]
}
}
这里还有一个答案??
好的。坚持住!之前所有的答案都是关于使用JSONSerialization，或返回nil，或忽略错误。
有什么不同
“我的解决方案”(不是真的我的解决方案，这是上述解决方案的混合)包含:
返回值的现代方法:Result<Value,Error>(返回值或错误)
避免使用空值
包含一个稍微详细的错误
使用扩展有漂亮/直观的界面:
提供了选择包的可能性
细节
Xcode 14
斯威夫特5.6.1
解决方案1。JSON文件->可解码
enum JSONParseError: Error {
case fileNotFound
case dataInitialisation(error: Error)
case decoding(error: Error)
}
extension Decodable {
static func from(localJSON filename: String,
bundle: Bundle = .main) -> Result<Self, JSONParseError> {
guard let url = bundle.url(forResource: filename, withExtension: "json") else {
return .failure(.fileNotFound)
}
let data: Data
do {
data = try Data(contentsOf: url)
} catch let error {
return .failure(.dataInitialisation(error: error))
}
do {
return .success(try JSONDecoder().decode(self, from: data))
} catch let error {
return .failure(.decoding(error: error))
}
}
}
方案一用途
struct Model: Decodable {
let uuid: String
let name: String
}
switch Model.from(localJSON: "myjsonfile") {
case .success(let value):
print(value)
case .failure(let error):
print(error)
}
解决方案2。JSON文件->字典
extension Dictionary where Key == String, Value == Any {
enum JSONParseError: Error {
case fileNotFound(filename: String)
case dataInitialisation(Error)
case jsonSerialization(Error)
case mappingFail(value: Any, toType: Any)
}
static func from(JSONfile url: URL) -> Result<Self, JSONParseError> {
let data: Data
do {
data = try Data(contentsOf: url)
} catch let error {
return .failure(.dataInitialisation(error))
}
let jsonObject: Any
do {
jsonObject = try JSONSerialization.jsonObject(with: data, options: .mutableLeaves)
} catch let error {
return .failure(.jsonSerialization(error))
}
guard let jsonResult = jsonObject as? Self else {
return .failure(.mappingFail(value: jsonObject, toType: Self.Type.self))
}
return .success(jsonResult)
}
static func from(localJSONfile name: String) -> Result<Self, JSONParseError> {
let fileType = "json"
let fullFileName = name + (name.contains(fileType) ? "" : ".\(fileType)")
guard let path = Bundle.main.path(forResource: fullFileName, ofType: "") else {
return .failure(.fileNotFound(filename: fullFileName))
}
return from(JSONfile: URL(fileURLWithPath: path))
}
}
方案二使用
switch [String: Any].from(localJSONfile: "file.json") {
// OR switch [String: Any].from(localJSONfile: "file.json") {
// OR switch [String: Any].from(JSONfile: url) {
case let .success(dictionary):
print(dictionary)
case let .failure(error):
print("ERROR: \(error)")
}
斯威夫特4。X和5。x使用可解码
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
}
斯威夫特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
}
在清理和抛光我的代码之后，我来到了这两个函数，你可以添加到你的项目中，并使用它们非常整洁和快速地从json文件读取数据，并将数据转换为你想要的任何类型!
public func readDataRepresentationFromFile(resource: String, type: String) -> Data? {
let filePath = Bundle.main.path(forResource: resource, ofType: type)
if let path = filePath {
let result = FileManager.default.contents(atPath: path)
return result
}
return nil
}
然后在这个函数的帮助下，你可以将你的数据转换为任何你想要的类型:
public func getObject<T: Codable>(of type: T.Type, from file: String) -> T? {
guard let data = readDataRepresentationFromFile(resource: file, type: "json") else {
return nil
}
if let object = try? JSONDecoder().decode(type, from: data) {
return object
}
return nil
}
此代码的应用示例:
在你的代码中调用这个函数，给它你的json文件的名字，这就是你所需要的!
func getInputDataFromSomeJson(jsonFileName: String) -> YourReqiuredOutputType? {
return getObject(of: YourReqiuredOutputType.self, from: jsonFileName)
}
