如何与不同类中的swing组件进行交互(How to interact with swing components in different classes)

 虽然莱昂纳多的答案是好的，但除非你知道对象是非可选的，否则它会导致异常，这是一个更好的模式，应该被视为伪代码： 
 
if let frame = NSScreen.screens()?.first?.frame {
   // Do something with frame.
}
 
 换句话说，使用可选链接（ ?. ），但只使用let与链的最后一部分。 
 
 如果要链接不同类型的选项，也可以创建这样的运算符，其中只返回最后一个的值： 
 
infix operator ??? { associativity left }

func ??? <T1, T2>(t1: T1?, t2: @autoclosure () -> T2?) -> T2? {
    return t1 == nil ? nil : t2()
}

if let frame = self.window ??? NSScreen.screens()?.first?.frame {
    // Do something with frame
}
 
 当然，这是受到Haskell的约束的启发。 但就像这样有趣，我不推荐它。 我认为这很明显是泥巴。 （顺便说一句， ???和??之间的区别???前者不要求lhs和rhs属于同一类型（或超类型），而后者则需要。 ???总是返回其rhs或nil 。） 

While Leonardo's answer is a good one, it can lead to exceptions unless you know the objects are non-optional, a better pattern is this, which should be regarded as pseudocode:
 
if let frame = NSScreen.screens()?.first?.frame {
   // Do something with frame.
}
 
In other words, use optional chaining (?.), but only use let with the very last part of the chain.
 
You could also create an operator like this if you want to chain optionals that are of a different type, in which only the value of the last one will be returned:
 
infix operator ??? { associativity left }

func ??? <T1, T2>(t1: T1?, t2: @autoclosure () -> T2?) -> T2? {
    return t1 == nil ? nil : t2()
}

if let frame = self.window ??? NSScreen.screens()?.first?.frame {
    // Do something with frame
}
 
This is, of course, inspired by Haskell's bind. But as fun as this is, I don't recommend it. I think it's clear as mud. (By the way, the difference between ??? and ?? is that the former does not require the lhs and rhs to be of the same type (or supertype), while the latter does. ??? always returns its rhs or nil.)