Swift 字符串 contains()

var message = "This is Swift Programming"

// check if message contains "Swift"
var result = message.contains("Swift")

print(result)

// Output: true

contains() 语法

字符串 contains() 方法的语法是

string.contains(char: charSequence)

此处，string 是 String 类的一个对象。

contains() 参数

contains() 方法接受一个参数。

• char (charSequence) - 字符序列

contains() 返回值

contains() 返回

• true - 如果字符串包含指定的字符序列
• false - 如果字符串不包含指定的字符序列

示例 1：Swift 字符串 contains()

var message = "Swift Programming Language"

// check if message contains "Swift"
var result = message.contains("Swift")
print(result)      // true

// check if message contains "Java"
result = message.contains("Java")
print(result)      // false

// check if message contains " "
result = message.contains(" ");
print(result)      // true

输出

true
false
true

在这里，message.contains(" ") 返回 true，因为空字符串是任何其他字符串的子集。

示例 2：使用 contains() 和 if...else

var message  = "Swift Programming Language"
var msg1 = "Swift"
var msg2 = "swift"
  
// true because message contains "Swift"
if (message.contains(msg1)) {

  print(message + " contains " + msg1)
}

else {

  print(message + " doesn't contain " + msg1)
}
  
// contains() is case-sensitive
// false because message doesn't contains "swift"
if (message.contains(msg2)) {

  print(message + " contains " + msg2)
}
else {

  print(message + " doesn't contain " + msg2)
}

输出

Swift Programming Language contains Swift
Swift Programming Language doesn't contain swift