快速查看JSONEncode（）输出的优美方法

Question

var test = [String : String] ()
test["title"] = "title"
test["description"] = "description"

let encoder = JSONEncoder()
let json = try? encoder.encode(test)

如何查看的输出json？

如果我print(json)唯一得到的是Optional(45 bytes)

Answer 1

该encode()方法返回Data包含UTF-8编码的JSON表示形式。因此，您可以将其转换回字符串：

var test = [String : String] ()
test["title"] = "title"
test["description"] = "description"

let encoder = JSONEncoder()
if let json = try? encoder.encode(test) {
    print(String(data: json, encoding: .utf8)!)
}

输出：

{“ title”：“ title”，“ description”：“ description”}

Answer 2

在 Swift 4 中，String有一个名为init(data:encoding:). init(data:encoding:)有以下声明：

init?(data: Data, encoding: String.Encoding)

返回String通过data使用给定的将给定转换为 Unicode 字符而初始化的encoding。

以下 Playground 片段显示了如何使用String init(data:encoding:)初始化程序来打印 JSON 数据内容：

import Foundation

var test = [String : String]()
test["title"] = "title"
test["description"] = "description"

let encoder = JSONEncoder()
if let data = try? encoder.encode(test),
    let jsonString = String(data: data, encoding: .utf8) {
    print(jsonString)
}

/*
 prints:
 {"title":"title","description":"description"}
 */

使用JSONEncoder.OutputFormattingset to 的替代方法prettyPrinted：

import Foundation

var test = [String : String]()
test["title"] = "title"
test["description"] = "description"

let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted

if let data = try? encoder.encode(test),
    let jsonString = String(data: data, encoding: .utf8) {
    print(jsonString)
}

/*
 prints:
 {
   "title" : "title",
   "description" : "description"
 }
 */