正则表达式字面量与匹配

let pattern = /hello/
if "hello world".contains(pattern) {
    print("Found hello")
}

let digits = /\d+/
if let m = "12345".wholeMatch(of: digits) {
    print("Whole match: \(m.output)")
} else {
    print("No whole match")
}

let word = /\w+/
if let m = "  swift rocks".firstMatch(of: word) {
    print("First word: \(m.output)")
}

let text = "abc123def"
if let m = text.firstMatch(of: /\d+/) {
    print("Matched: \(m.output)")
    print("At: \(text[m.range])")
}

let vowel = /[aeiou]/
if let m = "sky".firstMatch(of: vowel) {
    print("Vowel: \(m.output)")
} else {
    print("No vowels found")
}

let phone = /\d{3}-\d{4}/
print("555-1234".wholeMatch(of: phone) != nil)
print("12-34".wholeMatch(of: phone) != nil)

let startsWithCap = /^[A-Z]\w*/
if let m = "Swift".firstMatch(of: startsWithCap) {
    print("Matched: \(m.output)")
}

let pattern = /swift/.ignoresCase()
print("I love SWIFT".contains(pattern))

let nums = "a1 b22 c333"
for m in nums.matches(of: /\d+/) {
    print(m.output)
}

func isZip(_ s: String) -> Bool {
    s.wholeMatch(of: /\d{5}/) != nil
}
print(isZip("90210"))
print(isZip("ABCDE"))