一些Swift小知识点的整理

import UIKit
var names = []
class ViewController: UIViewController,UIAlertViewDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        var stringValue:String!
//        stringValue = "chw"
//        let str11 = stringValue.hashValue
//        var stringValue:Optional<String>
        if let str = stringValue {
            let hashValue = str.hashValue
        }
        let str1 = "swift"
        for k in str1 {
            println(k)
        }

        var dic = [0:0, 1:0, 2:0]
        var newDic = dic
        //Check dic and newDic
        dic[0] = 1
        println(dic)     //[0: 1, 1: 0, 2: 0]
        println(newDic)//[0: 0, 1: 0, 2: 0]

        var arr11:Array = [0,"lll",0]
        var newArr = arr11
        arr11[0] = 1
        //Check arr and newArr 
        println(arr11)    //[1, 0, 0]
        println(newArr) //[0, 0, 0]

//        字符串
        let heart = "❤️"
        println(heart)//❤️

        //空字符串
        let empty = ""
        let anotherEmpty = String()
        if empty.isEmpty {
            println(" empty ")
        } else {
            println(" not empty ")
        }

        //前缀后缀
        let str11 = "chengHong wei"
        if str11.hasPrefix("ch") {
            println("prefix is ch")
        }
        if str11.hasSuffix("wei") {
            println("suffix is wei")
        }

        //大小写
        let up = str11.uppercaseString
        println(up)//CHENGHONG WEI
        let low = str11.lowercaseString
        println(low)//chenghong wei

//        可选值探究
        var input:String?
        var input1 = "18"
        var age = input1.toInt()
        if age != nil{
            println("your age is " + String(age!))
        } else {
            println("error for input")
        }

//        遍历数组
        let arr = ["1","2","3"]
//        ...相当于[0,2]一个区间,意思就是 0=< i && i<= 2
        for i in 1...arr.count {
            println("arr count is \(arr.count)")
            println("arr object index \(arr[i-1])")
        }
//        ..<是半闭半开区间,意思就是[0,arr.count) (之前是..，现在已经改了)
        for i in 0..<arr.count {
            println(i)
        }
        for var i=0;i<3;i++ {
            println("\(arr)")
        }

//        array加元素
        var arr1 = ["a"]
        arr1 += ["b"]
        arr1 += ["c","d","e"]
        println(arr1)
        println("arr1 is \(arr1)")

        arr1[0] = "f"
        println(arr1)

        var arr20 = [1,2,3,4]
        arr20[0] = 0
        arr20[1...1] = [5,8]//在array[1]这儿插入了5，8两个元素，这个功能仅在区间状态有效，如果a[3] = [5,8] 则会报错
        println(arr20) //[0,5,8,3,4]

//        泛型是如何用来定义容器的存储的。还有一个数组的缩写形式，这个更具有可读性，但本质上是一样的。现在你不能往数组里面添加非Int型的元素。这听起来挺糟糕，但它非常有用。再也不需要用API来记录数组里存储了哪些从某个方法返回或者以属性存储的元素。你可以告诉编译器这些信息，编译器在错误检查方面会更加智能，并且可以提早做出优化。
        let arr2: [Int] = [1,2,3,4] //数组里面只能是int型

        let arr3: [Float] = [1,2,2.3]
        println("arr3 is \(arr3)")

        let arr4: [String] = ["1","chw","love"]
        println("arr4 is \(arr4)")

//        var 可变的数组是可以加元素的，let 声明的是不可加的,也就是可变与不可变数组的意思,在 Objective-C 和 Cocoa 中，您通过选择两个不同的类( NSString 和 NSMutableString )来指定该字符串是否可以被修改，Swift中的字符串是否可以修改仅通过定义的是变量还是常量来决定，实现了多种类型可变性操作的统一。
        var arr5:Array = [1,2,3,"cheng"]
        arr5.append("chw")
        println("arr5 is \(arr5)")

//        字典
        let dic11 = ["name":"chw","sex":1,"height":175.0]
        println("This is a dictionary \(dic11)")

//        Swift的=是没有返回值的
        var a1 = 5
        var a2 = 5
        if a1 == a2 {
            println("===")
        } else {
//            println("!==")
        }

//        字符串拼接
        let cheng = "c"
        let hong = "h"
        let wei = "w"
        let chenghongwei = cheng + hong + wei
        println("my name is \(chenghongwei)")

//      取余
        println(8%3) // = 2
        println(8%2.5) // 8 % 2.5 = 8 - 2.5 * 3 = 0.5 小数也是可以取余的

//        swith语句
        var i = 14
        switch i {
        case 0...10:
            println("range is 0-10")
        case 11...20:
            println("range is 11-20")
        case 21..<30:
            println("range is [21-30)")
        default:
            break
        }

        var name = "chw"
        switch name {
        case "cheng":
            println("name is cheng")
        case "hong":
            println("name is hong")
        case "wei":
            println("name is wei")
        default:
            println("someone else")
        break
        }

//        闭包初探
        names = ["Chris", "Alex", "Ewa", "Barry", "Daniella"]
        func backwards(s1:String,s2:String)->Bool {
            return s1>s2
        }

//        UI控件
        let lab = UILabel(frame: CGRectMake(100, 100, 200, 100))
        lab.text = "Hello Chw"
        lab.backgroundColor = UIColor.greenColor()
        lab.textAlignment = NSTextAlignment.Center
        self.view.addSubview(lab)

        let btn = UIButton(frame: CGRect(origin: CGPointMake(100,250), size: CGSizeMake(100,50)))
        btn.backgroundColor = UIColor.grayColor()
        btn.setTitle("Chw btn", forState: UIControlState.Normal)
        btn.addTarget(self, action: "btnClick:", forControlEvents: UIControlEvents.TouchUpInside)
        self.view.addSubview(btn)

} 

//TODO:---
    func btnClick(sender:UIButton!){
        println("chw 111")
        var alert = UIAlertView()
        alert.title = "CHW"
        alert.delegate = self
        alert.message = " This is a alert !"
        alert.addButtonWithTitle("Cancle")
        alert.addButtonWithTitle("OK")
        alert.show()

    }

//MARK:-
//MARK:--- AlertViewdelegate
    func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int){
        println("buttonIndex:\(buttonIndex)")
        if buttonIndex == 0 {
           println("Cancle Btn !")
        } else if buttonIndex == 1 {
           println("Sure Btn")
        }
    }
//MARK:-
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}