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。
简化Peter Kreinz提供的例子。适用于Swift 4.2。
扩展函数:
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
}
}
示例模型:
struct Service: Decodable {
let name: String
}
示例用法:
/// service.json
/// { "name": "Home & Garden" }
guard let output = Service.parse(jsonFile: "service") else {
// do something if parsing failed
return
}
// use output if all good
这个例子也适用于数组:
/// services.json
/// [ { "name": "Home & Garden" } ]
guard let output = [Service].parse(jsonFile: "services") else {
// do something if parsing failed
return
}
// use output if all good
注意，我们没有提供任何不必要的泛型，因此不需要强制转换parse的结果。
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
}
遵循以下代码:
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
}
}
}
}
数组“persons”将包含关键人物的所有数据。遍历获取它。
斯威夫特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
}
}
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)
}
