为什么不允许快速切换开关盒的概念？

Question

var index = 30 

switch index { 

    case 10 :  
     println("Value of index is 10") 
    case 20 : 

    case 30 :  
     println("Value of index is either 20 or 30") 
    case 40 :  
     println("Value of index is 40") 
    default :  
     println("default case") 
} 

Answer 1

下通是允许在斯威夫特，但you do have to state it explicitly：

switch index { 
case 10: 
    println("Value of index is 10") 
case 20: 
    fallthrough 
case 30: 
    println("Value of index is either 20 or 30") 
... 

因为虽然你的情况，它可能会更好，只是组的情况：

switch index { 
case 10: 
    println("Value of index is 10") 
case 20, 30: 
    println("Value of index is either 20 or 30") 
... 

Answer 2

或者你可以把它写这样（ Swift 2.2语法）：

switch index { 
case 10: 
    print("Value is: \(index)") 
case 20, 30: 
    print("Value is: \(index)") 
default: 
    print("Default value is: \(index)") 
}