Swift if...else if...else Statement

Swift Conditional Statements

Anif statementcan be followed by an optionalelse if...else statement，else if...else statementIt is very useful when testing multiple conditions.

When you use if, else if, else statements, you need to note the following points:

• An if statement can be followed by 0 or 1 else, but if there is an else if statement, the else statement needs to be after the else if statement.
• An if statement can be followed by 0 or more else if statements, and the else if statements must appear before the else statement.
• Once an if statement executes successfully, the other else if or else statements will not execute.

Syntax

if boolean_expression_1 {
   /* 如果 boolean_expression_1 表达式为 true 则执行该语句 */
} else if boolean_expression_2 {
   /* 如果 boolean_expression_2 表达式为 true 则执行该语句 */
} else if boolean_expression_3 {
   /* 如果 boolean_expression_3 表达式为 true 则执行该语句 */
} else {
   /* 如果以上所有条件表达式都不为 true 则执行该语句 */
}

Example

import Cocoa

var varA:Int = 100;

/* 检测布尔条件 */
if varA == 20 {
    /* 如果条件为 true 执行以下语句 */
    print("varA 的值为 20");
} else if varA == 50 {
    /* 如果条件为 true 执行以下语句 */
    print("varA 的值为 50");
} else {
    /* 如果以上条件都为 false 执行以下语句 */
    print("没有匹配条件");
}
print("varA 变量的值为 \(varA)");

When the above code is compiled and executed, it produces the following results:

没有匹配条件
varA 变量的值为 100

Swift Conditional Statements