在Swift模式匹配元组时如何解包Optional？ [英] How do I unwrap an Optional when pattern matching tuples in Swift?

问题描述

在Swift中，如果让模式用于解包选项，则会有一个共同的：

In Swift, there's a common if let pattern used to unwrap optionals:

if let value = optional {
    print("value is now unwrapped: \(value)")
}

我目前正在进行这种模式匹配，但在切换情况下使用元组，其中两个参数都是可选项：

I'm currently doing this kind of pattern matching, but with tuples in a switch case, where both params are optionals:

//url is optional here
switch (year, url) {
    case (1990...2015, let unwrappedUrl):
        print("Current year is \(year), go to: \(unwrappedUrl)")
}       

然而，这打印：

"Current year is 2000, go to Optional(www.google.com)"

我有没有办法解开我的可选和模式匹配，只有它不是零？目前我的解决方法是：

Is there a way I can unwrap my optional and pattern match only if it's not nil? Currently my workaround is this:

switch (year, url) {
    case (1990...2015, let unwrappedUrl) where unwrappedUrl != nil:
        print("Current year is \(year), go to: \(unwrappedUrl!)")
}       

推荐答案

您可以使用 x？模式：

case (1990...2015, let unwrappedUrl?):
    print("Current year is \(year), go to: \(unwrappedUrl)")

x？ 只是 .some（x）的快捷方式，所以这相当于

x? is just a shortcut for .some(x), so this is equivalent to

case (1990...2015, let .some(unwrappedUrl)):
    print("Current year is \(year), go to: \(unwrappedUrl)")

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