在Swift模式匹配元组时如何解包Optional？

Question

在Swift中,有一个if let用于解包选项的常见模式:

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:

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

但是,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:

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

Answer 1

你可以使用这种x?模式:

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

x?只是一个捷径.some(x),所以这相当于

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