1.switch 可以不加break。
2.switch必须加default方法。如果不加的话，必须把所有条件都有其对应方法，才可以，否则会报错。
//可以是整数
let integerSwitch = 3
switch(integerSwitch){
case 0:
print("0");
case 1:
print("1");
case 2:
print("2");
default:
print("3")
}
//可以是字符串
let stringSwitch = "hello"
switch stringSwitch {
case "hello":
print("允许")
case"good night":
print("告辞")
default:
print("其它")
}
//范围
let someNumber = 15
switch someNumber {
case 0...10:
print("number is between 0 and 10.")
case 10...20:
print("number is between 0 and 10.")
case 20...30:
print("number is between 0 and 10.")
default:
print("number is not there.")
}
//集合
let tupleSwitch = ("Yes",123)
switch tupleSwitch{
case("Yes",123):
print("Yes and 123");
case("Yes",_):
print("yes and something alse");
default:
print("no have.")
}
