如果判斷一個整體string是否是一個URL,可以直接用URL來創建一個實例,當然也可以用下面的正則判斷:
func checkURL(_ url: String) -> Bool {
let pattern = "(https?|ftp|file)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+[-A-Za-z0-9+&@#/%=~_|]"
let pred = NSPredicate(format: "SELF MATCHES %@", pattern)
let isMatch = pred.evaluate(with: url)
return isMatch
}