Swift 中的 switch 语句更具表现力。我想知道这是否可能:
让我们看看 UIViewAutoresizing 的例子。它在 Objective-C 中的定义如下:
typedef NS_OPTIONS(NSUInteger, UIViewAutoresizing) {
UIViewAutoresizingNone = 0,
UIViewAutoresizingFlexibleLeftMargin = 1 << 0,
UIViewAutoresizingFlexibleWidth = 1 << 1,
UIViewAutoresizingFlexibleRightMargin = 1 << 2,
UIViewAutoresizingFlexibleTopMargin = 1 << 3,
UIViewAutoresizingFlexibleHeight = 1 << 4,
UIViewAutoresizingFlexibleBottomMargin = 1 << 5
};
我可以在 Swift 中像枚举一样使用它:
let foo = UIViewAutoresizing([.FlexibleHeight, .FlexibleTopMargin])
是否可以使用 switch 语句来代替多个 if 语句?
if foo & UIViewAutoresizing.FlexibleHeight != nil {
}
if foo & UIViewAutoresizing.FlexibleWidth != nil {
}
if foo & UIViewAutoresizing.FlexibleTopMargin != nil {
}
像这样的伪代码:
switch foo { // ** THIS IS PSEUDO CODE AND WILL NOT COMPILE **
case & .FlexibleHeight:
println("height")
case & .FlexibleWidth:
println("width")
case & .FlexibleTop:
println("top")
}