函数接受可变数量的参数

In this document: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/GuidedTour.html#//apple_ref/doc/uid/TP40014097-CH2-XID_1

在这个文档:https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/GuidedTour.html / / apple_ref / doc / uid / TP40014097-CH2-XID_1

It mentions that when creating for loops we can use the shorthand of 0..3 and 0...3 to replace i = 0; i < 3; ++i and i = 0; i <= 3; ++i respectively.

它提到，当创建for循环时，我们可以使用0的简写。3和0…3替换i = 0;我< 3;+i和i = 0;< = 3;+ +我分别。

All very nice.

都很好。

Further down the document in the Functions and Closures section it says that functions can have a variable number of arguments passed via an array.

在函数和闭包部分的文档后面，它说函数可以通过数组传递可变数量的参数。

However, in the code example we see the ... again.

然而，在代码示例中，我们看到…一次。

func sumOf(numbers: Int...) -> Int {
var sum = 0
for number in numbers {
sum += number
}
return sum
}

Is this a mistake? It seems to me that a more intuitive syntax would be numbers: Int[].

这是一个错误吗?在我看来，更直观的语法应该是数字:Int[]。

A few examples down we see another code sample which has exactly that:

下面有几个例子，我们看到另一个代码示例，它有:

func hasAnyMatches(list: Int[], condition: Int -> Bool) -> Bool {

2 个解决方案

#1

In case of all arguments are Int numbers: Int[] would be intuitive. But if you have code like this:

如果所有参数都是Int数:Int[]将是直观的。但是如果你有这样的代码:

func foo(args:AnyObject...) {
    for arg: AnyObject in args {
        println(arg)
    }
}

foo(5, "bar", NSView())

output:

输出:

5
bar
<NSView: 0x7fc5c1f0b450>

#2

The type of parameter in sumOf are known as 'variadic' parameter. The parameters passed are accepted just as a group of elements and is then converted into array before using it within that function.

sumOf中的参数类型称为“可变参数”。传递的参数作为一组元素接受，然后在函数中使用之前转换为数组。

A great example would be this post.

这篇文章就是一个很好的例子。

Passing lists from one function to another in Swift

在Swift中从一个函数到另一个函数的列表。

#1