Swift学习之方法定义参数有默认值的时候

func testParms(first fir:String, options opt:JSONSerialization.ReadingOptions = []) -> Bool {

return true

}

此时调用的时候

方法一

let test = testParms(first: "测试")

方法二

let test2 = testParms(first: "测试", options: .mutableContainers)