在Swift中将字典转换为JSON
我已经创build了下一个词典：
var postJSON = [ids[0]:answersArray[0], ids[1]:answersArray[1], ids[2]:answersArray[2]] as Dictionary 我得到：
[2: B, 1: A, 3: C]
那么，我怎样才能把它转换成JSON呢？
Swift 3.0
使用Swift 3，根据Swift APIdevise指南 ， NSJSONSerialization的名称及其方法已经改变。
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) }
Swift 2.x
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 } }
你正在做一个错误的假设。 仅仅因为debugging器/游乐场在方括号中显示你的字典（这是Cocoa如何显示字典）并不意味着这是JSON输出格式化的方式。
以下是将string字典转换为JSON的示例代码：
Swift 3版本：
import UIKit import AVFoundation 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”格式显示上述内容，您需要将选项行更改为：
options: [.prettyPrinted]
或者在Swift 2语法中：
import UIKit import AVFoundation 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!)")
这是输出
"JSON string = {"anotherKey":"anotherValue","aKey":"aValue"}"
或者以相当的格式：
{ "anotherKey" : "anotherValue", "aKey" : "aValue" }
正如您所期望的那样，字典在JSON输出中用大括号括起来。
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)") }
}
我的答案是你的问题在下面
let dict = ["0": "ArrayObjectOne", "1": "ArrayObjecttwo", "2": "ArrayObjectThree"] var error : NSError? let jsonData = try! NSJSONSerialization.dataWithJSONObject(dict, options: NSJSONWritingOptions.PrettyPrinted) let jsonString = NSString(data: jsonData, encoding: NSUTF8StringEncoding)! as String print(jsonString)
答案是
{ "0" : "ArrayObjectOne", "1" : "ArrayObjecttwo", "2" : "ArrayObjectThree" }
有时需要打印出服务器的响应以进行debugging。 这是我使用的一个函数：
extension Dictionary { var json: String { let invalidJson = "Not a valid JSON" do { let jsonData = try JSONSerialization.data(withJSONObject: self, options: .prettyPrinted) return String(bytes: jsonData, encoding: String.Encoding.utf8) ?? invalidJson } catch { return invalidJson } } func printJson() { print(json) } }
使用示例：
(lldb) po dictionary.printJson() { "InviteId" : 2, "EventId" : 13591, "Messages" : [ { "SenderUserId" : 9514, "MessageText" : "test", "RecipientUserId" : 9470 }, { "SenderUserId" : 9514, "MessageText" : "test", "RecipientUserId" : 9470 } ], "TargetUserId" : 9470, "InvitedUsers" : [ 9470 ], "InvitingUserId" : 9514, "WillGo" : true, "DateCreated" : "2016-08-24 14:01:08 +00:00" }
回答你的问题如下：
Swift 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) }
Swift 3 ：
let jsonData = try? JSONSerialization.data(withJSONObject: dict, options: []) let jsonString = String(data: jsonData!, encoding: .utf8)! print(jsonString)
