嵌套 if 语句（nested if statements）

在Swift 4中嵌套if-else语句总是合法的，这意味着你可以使用一个if else if else if语句。

语法 (Syntax)

nested if语句的语法如下 -

if boolean_expression_1 {
   /* Executes when the boolean expression 1 is true */
   if boolean_expression_2 {
      /* Executes when the boolean expression 2 is true */
   }
}

您可以使用与嵌套if语句类似的方式嵌套if else if...else 。

例子 (Example)

var varA:Int = 100;
var varB:Int = 200;
/* Check the boolean condition using if statement */
if varA == 100 {
   /* If condition is true then print the following */
   print("First condition is satisfied");
   if varB == 200 {
      /* If condition is true then print the following */
      print("Second condition is also satisfied");
   }
}
print("Value of variable varA is \(varA)");
print("Value of variable varB is \(varB)");

编译并执行上述代码时，会产生以下结果 -

First condition is satisfied
Second condition is also satisfied
Value of variable varA is 100
Value of variable varB is 200