iOS: 学习笔记, swift扩展

//

//  YYExtension.swift

//

//  Created by yao_yu on 14-7-18.

//  Copyright (c) 2014年 yao_yu. All rights reserved.

//



import Foundation



extension 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]

    }

}