如果判断一个整体string是否是一个URL,可以直接用URL来创建一个实例,当然也可以用下面的正则判断:
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
}