Swift3 Scanner用法之判断是否数字、提取字符串里的数字

/// 判断是否是数字
///
/// - Parameter string: <#string description#>
/// - Returns: <#return value description#>
class func isPurnInt(string: String) -> Bool {

let scan: Scanner = Scanner(string: string)

var val:Int = 0

return scan.scanInt(&val) && scan.isAtEnd

}

/// 从字符串中提取数字
class func getIntFromString(str:String) -> String {
let scanner = Scanner(string: str)
scanner.scanUpToCharacters(from: CharacterSet.decimalDigits, into: nil)
var number :Int = 0

scanner.scanInt(&number)

print(number)
return String(number)

}