爲什麼不允許快速切換開關盒的概念？

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

下通是允許在斯威夫特，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") 
... 

因爲雖然你的情況，它可能會更好，只是組的情況：

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

Answer 2

或者你可以把它寫這樣（ Swift 2.2語法）：

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