option[] in JSONSerialization

Question

什么是选项：[] in JSONSerialization in What

let jsonData = try JSONSerialization.data(withJSONObject: updatedJson, options: [])

Answer 1

JSONSerialization.WritingOptions是一个OptionSet，符合ExpressibleByArrayLiteral协议，这意味着可以将“选项集”指定为数组文本。例如：

let jsonData = try JSONSerialization.data(withJSONObject: json,
                                         options: [.prettyPrinted, .sortedKeys])

特别是，空数组文字意味着“无选项”：

let jsonData = try JSONSerialization.data(withJSONObject: json, options: [])

在这种情况下，这相当于省略参数。

let jsonData = try JSONSerialization.data(withJSONObject: json)

因为它的默认值为[]。

class func data(withJSONObject obj: Any, 
    options opt: JSONSerialization.WritingOptions = []) throws -> Data