Question

请使用以下代码：

var tupleArray: [(firstName: String, middleName: String?)] = []
tupleArray.append(firstName: "Bob", middleName: nil)
tupleArray.append(firstName: "Tom", middleName: "Smith") // causes an error

我想要一个由名字和中间名组成的元组数组，中间名可以是nil或者有一个值（因此，可选）。但是使用上面的创建代码，第三行给了我一个错误。为什么？我该如何解决这个问题？

Answer 1

这可能是编译器错误。与How do I create an array of tuples?中一样，您可以将类型别名定义为变通方法：

typealias NameTuple = (firstName: String, middleName: String?)

var tupleArray: [NameTuple] = []
tupleArray.append( (firstName: "Bob", middleName: nil) )
tupleArray.append( (firstName: "Tom", middleName: "Smith") )

Answer 2

另一种解决方法是明确制作Optional<String>.Some。

var tupleArray: [(firstName: String, middleName: String?)] = []
tupleArray.append(firstName: "Bob", middleName: nil)
tupleArray.append(firstName: "Tom", middleName: .Some("Smith"))

Answer 3

Something Intresting.It似乎是一些bug，但我们可以使用其他语法添加尝试使用以下方式

var pfc : [(prime: Int, count: Int)] = []

pfc.append(prime: 2, count: 2)

pfc += [(prime: 3, count: 4)]

var p = 5
var c = 1

var tuple = (prime: p, count: c)

pfc += [tuple]

对于optinal变量，请看下面的代码（originally provided by Martin R），它适用于我

    typealias tupleArray =  (firstName: String, middleName: String?)

    var fun1: [tupleArray] = [tupleArray]()
    fun1.append((firstName: "Bob", middleName: nil))
    fun1.append((firstName: "Tom", middleName: "Smith"))
    println(fun1)

如何在Swift中创建一个元组数组，其中元组中的一个项是可选的？

3 个答案: