本篇中主要介绍Swift 2.0语言的新特性, 包括 Swift 语言引入的错误处理机制，以及对 ErrorType 的概述。

Swift 2.0 新特性

var a = "SDsadad";for string in a.characters{}

1.错误处理

throws throw
do try catch
ErrorType协议

 enum error：ErrorType{
    case 没空
    case 器材损坏
    case 低体力
 }
 let 剩余时间 ＝ 30.0
 let 器械良好 = true
 let 体力 ＝ 0.0

 // 有先后顺序
 func  检查健身实施情况() throws{
    guard 剩余时间 > 0.0 else{
        throw error.没空
    }
    guard 器械良好 else {
        throw error.器材损坏
    }
    guard 低体力 > 0.0 else{
        throw error.低体力
    }
 }
 func begin(){
    do{
        try 检查健身实施情况(){
            print("健身开始")
        }catch error.没空｛
            print("")
        ｝catch error.器材损坏｛
            print("")
        ｝catch error.低体力｛
            print("")
        ｝catch{
            print("其它原因")
        }
    }
 }

2.协议扩展 , 类间接扩展

    protocol Velocity{
        func accelerationTimePer100KM() -> Double
    }

    struct Carola:Velocity{
        var price:Int
        func accelerationTimePer100KM() -> Double{
            return 3.0
        }
    }
    struct Psyche:Velocity{
        var price:Int
        func accelerationTimePer100KM() -> Double{
            return 2.5
        }
    }

    let Carola1 = Carola(price:100000)
    Carola1.accelerationTimePer100KM()

    let Psyche1 = Psyche(price:100000)
    Psyche1.accelerationTimePer100KM()

    extension Velocity{
        var rank:Int{
            get{
                return Int(ccelerationTimePer100KM() * 10)
            }
        }
    }

    //自动获得  rank
    Carola1.rank
    Psyche1.rank

3.有效性检查(API兼容性)


    if #available(iOS8,*){
        let queryItem = NSURLQueryItem()
    }else{
        // iOS旧版本
    }

4. do while 循环重命名为repeat while 循环


    var i = 1
    repeat{
        i++
        print(i)
    }while i <= 10

OptionSet:

 import Foundation

 struct Inputs:OptionSetType {
    let rawValue:Int
    static let user = Inputs(rawValue: 1 << 0)
    static let pass = Inputs(rawValue: 1 << 1)
    static let mail = Inputs(rawValue: 1 << 2)

 }

 // judge whether input all
 extension Inputs{
    func isAllOK() -> Bool{
 //        return self == [.user, .pass, .mail]
 //        return self.rawValue == 0b111
        let count = 3
        // serach items
        var found = 0

        for time in 0..<count{
            if self.contains(Inputs(rawValue:1 << time)){
                found++
            }
        }
        // 是否全部找到
        return found == count

    }
 }

 let possibleInputs:Inputs = [.user, .pass, .mail]
 possibleInputs.isAllOK()

将if条件语句提前，并且将 if 改为 where for time in 0..<count where contains(Inputs(rawValue:1 << time)){//code}