如何在Swift模式匹配元組時解開一個Optional？

Question

在斯威夫特，還有用來解開自選共同if let模式：

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

目前，我正在做這種模式匹配的，但在一個開關的情況下元組，其中兩個PARAMS是選配：

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

然而，這種打印：

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

有沒有一種方法，我可以解開我的，只有當它是可選的模式匹配不是零？目前，我的解決方法是這樣的：

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

Answer 1

可以使用x?模式：

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

x?是j UST爲.some(x)一個快捷方式，所以這相當於

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

Answer 2

，你可以這樣做：

switch(year, x) { 
    case (1990...2015,.Some): 
    print("Current year is \(year), go to: \(x!)") 
} 

，你也可以做

switch(year, x) { 
    case (1990...2015, let .Some(unwrappedUrl)): 
    print("Current year is \(year), go to: \(unwrappedUrl)") 
}