Swift 2-检查空数组的类型(自省) [英] Swift 2 - Check Type of empty Array (Introspection)

问题描述

我目前正在Swift 2中进行自省，在获取数组的特定类型(在此示例中为Array<String>)时遇到问题.

I'm currently working on introspection in Swift 2 and have Problems getting the specific type for an Array (in this example an Array<String>).

var prop = obj.valueForKey("strings")!

if prop is Array<String> {
println("true")
}
if prop is Array<Int> {
println("true")
}

输出为:

true
true

应该是

true
false

是否可以找出数组成员的类型?例如，如果我将数组声明为Array<String>，我想获取String或至少能够检查如果是. 到目前为止， MirrorType 并没有取得任何成功.

Is there a way to find out the type for the members of the Array? For example, if I daclared the Array as Array<String> I want to get String or at least be able to check if it is. MirrorType also did not lead to any success on that by now.

推荐答案

有两种方法可以实现所需的目标:

There are 2 ways to achieve what you want:

比if prop.dynamicType == [Int]().dynamicType {更好的
1. if prop.dynamicType == Array<Int>.self(或[Int].self)，因为[Int]()创建了一个未使用的整数数组"实例.
2. 通常，当您检查数组是否为特定类型的数组时，您打算使用它 以某种方式(结果，您可能会将数组强制转换为 [Int]).话虽如此，我建议使用if let arrayOfInts = prop as? Array<Int> {.使用此构造，您将检查 类型兼容性，并准备以特殊方式处理数组(使用强制转换的arrayOfInts引用).

1. if prop.dynamicType == Array<Int>.self (or [Int].self) which is better than if prop.dynamicType == [Int]().dynamicType { because [Int]() creates an unused instance of "array of integers".
2. Typically, when you check if an array is specific-typed, you plan to use it in a certain way (as a result, you will likely cast your array to [Int]). Having that said, I recommend using if let arrayOfInts = prop as? Array<Int> {. Using this construct, you will check for type compatibility and prepare your array to be treated in a special way (using the casted arrayOfInts reference).

无论如何，由您决定做什么.

Anyway, it's up to you to decide what to do.

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