////  YYExtension.swift////  Created by yao_yu on 14-7-18.//  Copyright (c) 2014年 yao_yu. All rights reserved.//import Foundationextension String{    func strip() -> String{        return stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())    }        func split(separator: String) -> [String]{        return componentsSeparatedByString(separator)    }        var doubleValue:Double!{    return (self as NSString).doubleValue    }        var length:Int{    return countElements(self)    }        func isValidRange(range: Range<Int>) -> Bool{        return range.startIndex >= 0 && range.endIndex <= length    }        subscript (range: Range<Int>) -> String {        assert(isValidRange(range), "范围超出字符串长度")            var startIndex:String.Index = advance(self.startIndex, range.startIndex)            var endIndex:String.Index = advance(startIndex, range.endIndex - range.startIndex)            return self.substringWithRange(Range(start: startIndex, end: endIndex))    }        subscript (index: Int) -> String{        return self[index...index]    }        func at (indexes: Int...) -> [String] {        return indexes.map { self[$0] }    }        func at (indexes: [Int]) -> [String] {        return indexes.map { self[$0] }    }}extension Array {    func take(n: Int) -> SliceType{        return self[0 ..< n]    }        func tail (n: Int) -> SliceType {        return self[(count - n) ..< count]    }        func skip (n: Int) -> SliceType {        return self[n ..< count]    }}