我已经创建了下一个字典:
var postJSON = [ids[0]:answersArray[0], ids[1]:answersArray[1], ids[2]:answersArray[2]] as Dictionary
得到:
[2: B, 1: A, 3: C]
那么,如何将其转换为JSON呢?
我已经创建了下一个字典:
var postJSON = [ids[0]:answersArray[0], ids[1]:answersArray[1], ids[2]:answersArray[2]] as Dictionary
得到:
[2: B, 1: A, 3: C]
那么,如何将其转换为JSON呢?
当前回答
斯威夫特3.0
在Swift 3中,NSJSONSerialization的名字和它的方法已经改变了,根据Swift API设计指南。
let dic = ["2": "B", "1": "A", "3": "C"]
do {
let jsonData = try JSONSerialization.data(withJSONObject: dic, options: .prettyPrinted)
// here "jsonData" is the dictionary encoded in JSON data
let decoded = try JSONSerialization.jsonObject(with: jsonData, options: [])
// here "decoded" is of type `Any`, decoded from JSON data
// you can now cast it with the right type
if let dictFromJSON = decoded as? [String:String] {
// use dictFromJSON
}
} catch {
print(error.localizedDescription)
}
快2.倍
do {
let jsonData = try NSJSONSerialization.dataWithJSONObject(dic, options: NSJSONWritingOptions.PrettyPrinted)
// here "jsonData" is the dictionary encoded in JSON data
let decoded = try NSJSONSerialization.JSONObjectWithData(jsonData, options: [])
// here "decoded" is of type `AnyObject`, decoded from JSON data
// you can now cast it with the right type
if let dictFromJSON = decoded as? [String:String] {
// use dictFromJSON
}
} catch let error as NSError {
print(error)
}
斯威夫特1
var error: NSError?
if let jsonData = NSJSONSerialization.dataWithJSONObject(dic, options: NSJSONWritingOptions.PrettyPrinted, error: &error) {
if error != nil {
println(error)
} else {
// here "jsonData" is the dictionary encoded in JSON data
}
}
if let decoded = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: &error) as? [String:String] {
if error != nil {
println(error)
} else {
// here "decoded" is the dictionary decoded from JSON data
}
}
其他回答
斯威夫特3:
let jsonData = try? JSONSerialization.data(withJSONObject: dict, options: [])
let jsonString = String(data: jsonData!, encoding: .utf8)!
print(jsonString)
你问题的答案如下:
斯威夫特2.1
do {
if let postData : NSData = try NSJSONSerialization.dataWithJSONObject(dictDataToBeConverted, options: NSJSONWritingOptions.PrettyPrinted){
let json = NSString(data: postData, encoding: NSUTF8StringEncoding)! as String
print(json)}
}
catch {
print(error)
}
2022年,swift 5
扩展的使用:
编码:
if let json = statisticsDict.asJSONStr() {
//your action with json
}
从字典解码:
json.decodeFromJson(type: [String:AppStat].self)
.onSuccess{
$0// your dictionary of type: [String:AppStat]
}
扩展:
extension Dictionary where Key: Encodable, Value: Encodable {
func asJSONStr() -> String? {
let encoder = JSONEncoder()
if let jsonData = try? encoder.encode(self) {
if let jsonString = String(data: jsonData, encoding: .utf8) {
return jsonString
}
}
return nil
}
}
public extension String {
func decodeFromJson<T>(type: T.Type) -> Result<T, Error> where T: Decodable {
self.asData()
.flatMap { JSONDecoder().try(type, from: $0) }
}
func asData() -> Result<Data, Error> {
if let data = self.data(using: .utf8) {
return .success(data)
} else {
return .failure(WTF("can't convert string to data: \(self)"))
}
}
}
extension JSONDecoder {
func `try`<T: Decodable>(_ t: T.Type, from data: Data) -> Result<T,Error> {
do {
return .success(try self.decode(t, from: data))
} catch {
return .failure(error)
}
}
}
在Swift 5.4中
extension Dictionary {
var jsonData: Data? {
return try? JSONSerialization.data(withJSONObject: self, options: [.prettyPrinted])
}
func toJSONString() -> String? {
if let jsonData = jsonData {
let jsonString = String(data: jsonData, encoding: .utf8)
return jsonString
}
return nil
}
}
把它作为变量的想法是,这样你就可以像这样重用它:
extension Dictionary {
func decode<T:Codable>() throws -> T {
return try JSONDecoder().decode(T.self, from: jsonData ?? Data())
}
}
你的假设是错误的。只是因为调试器/Playground用方括号显示你的字典(这是Cocoa显示字典的方式),这并不意味着这是JSON输出格式化的方式。
下面是将字符串字典转换为JSON的示例代码:
Swift 3版本:
import Foundation
let dictionary = ["aKey": "aValue", "anotherKey": "anotherValue"]
if let theJSONData = try? JSONSerialization.data(
withJSONObject: dictionary,
options: []) {
let theJSONText = String(data: theJSONData,
encoding: .ascii)
print("JSON string = \(theJSONText!)")
}
要以“漂亮打印”的格式显示上面的内容,你可以将选项行更改为:
options: [.prettyPrinted]
或者在Swift 2语法中:
import Foundation
let dictionary = ["aKey": "aValue", "anotherKey": "anotherValue"]
let theJSONData = NSJSONSerialization.dataWithJSONObject(
dictionary ,
options: NSJSONWritingOptions(0),
error: nil)
let theJSONText = NSString(data: theJSONData!,
encoding: NSASCIIStringEncoding)
println("JSON string = \(theJSONText!)")
它的输出是
"JSON string = {"anotherKey":"anotherValue","aKey":"aValue"}"
或者用漂亮的格式:
{
"anotherKey" : "anotherValue",
"aKey" : "aValue"
}
正如您所期望的那样,在JSON输出中,字典用花括号括起来。
编辑:
在Swift 3/4语法中,上面的代码看起来像这样:
let dictionary = ["aKey": "aValue", "anotherKey": "anotherValue"]
if let theJSONData = try? JSONSerialization.data(
withJSONObject: dictionary,
options: .prettyPrinted
),
let theJSONText = String(data: theJSONData,
encoding: String.Encoding.ascii) {
print("JSON string = \n\(theJSONText)")
}
}