1 对数组中所有元素进行加倍操作
(1...1024).map{$0 * 2}
2 对数组所有元素进行求和
(1...<1024).reduce(0,combine:+)// 0为初始值 + 为闭包操作简写
3 验证字符串中是否存在某个子串
复杂版本：
let words = ["Swift","iOS","cocoa","OSX","tvOS"]
let tweet = "This is an example tweet larking about Swift"
let valid = !words.filter({tweet.containsString($0)}).isEmpty
valid // true
对map,reduce,filter函数底层实现不够了解，请点击我写的Why coding like this 系列文章。
想了想，还是对上面这个例子简单介绍下，首先我们使用filter函数，顾名思义就是进行“过滤”操作，过滤的条件就是tweet.containsString($0) ，即tweet字符串包含$0，问题又来了，$0表示什么？了解过闭包的童鞋应该知道，即传入闭包的第一个参数，也就是遍历数组的当前元素；words.filter({tweet.containsString($0)})会返回满足条件的所有元素组成的集合，调用isEmpty确认集合是否为空，!取反。
简明版本：
words.contains(tweet.containsString)
//或者先对tweet字符串进行操作
tweet.characters
.split(" ")
.lazy
.map(String.init)
.contains(Set(words).contains)
4 读取文件
let path = NSBundle.mainBundle().pathForResource("test", ofType: "txt")
// 先读取文件到String 中，然后通过换行`\n`来分割字符串到数组中
let lines = try? String(contentsOfFile: path!).characters.split{$0 == "\n"}.map(String.init)
if let lines=lines {
lines[0] // O! for a Muse of fire, that would ascend
lines[1] // The brightest heaven of invention!
lines[2] // A kingdom for a stage, princes to act
lines[3] // And monarchs to behold the swelling scene.
}
5 生日快乐
let name = "uraimo"
(1...4).forEach{print("Happy Birthday " + (($0 == 3) ? "dear \(name)":"to You"))}
6 屏蔽数组中满足特定条件的元素
extension SequenceType{
typealias Element = Self.Generator.Element
func partitionBy(fu: (Element)->Bool)->([Element],[Element]){
var first=[Element]()
var second=[Element]()
for el in self {
if fu(el) {
first.append(el)
}else{
second.append(el)
}
}
return (first,second)
}
}
let part = [82, 58, 76, 49, 88, 90].partitionBy{$0 < 60}
part // ([58, 49], [82, 76, 88, 90])
以上方法并非是一句话哦，所以还要寻求另外的方式：
extension SequenceType{
func anotherPartitionBy(fu: (Self.Generator.Element)->Bool)->([Self.Generator.Element],[Self.Generator.Element]){
return (self.filter(fu),self.filter({!fu($0)}))
}
}
let part2 = [82, 58, 76, 49, 88, 90].anotherPartitionBy{$0 < 60}
part2 // ([58, 49], [82, 76, 88, 90])
基本满足，但是效率不行，因为遍历了数组两次。
下面依靠reduce方法进行操作：
var part3 = [82, 58, 76, 49, 88, 90].reduce( ([],[]), combine: {
(a:([Int],[Int]),n:Int) -> ([Int],[Int]) in
(n<60) ? (a.0+[n],a.1) : (a.0,a.1+[n])
})
part3 // ([58, 49], [82, 76, 88, 90])
7 从服务器获取XML文件并解析
其实也可以是获取JSON文件并解析，童鞋们可自行尝试
let xmlDoc = try? AEXMLDocument(xmlData: NSData(contentsOfURL: NSURL(string:"https://www.ibiblio.org/xml/examples/shakespeare/hen_v.xml")!)!)
if let xmlDoc=xmlDoc {
var prologue = xmlDoc.root.children[6]["PROLOGUE"]["SPEECH"]
prologue.children[1].stringValue // Now all the youth of England are on fire,
prologue.children[2].stringValue // And silken dalliance in the wardrobe lies:
prologue.children[3].stringValue // Now thrive the armourers, and honour's thought
prologue.children[4].stringValue // Reigns solely in the breast of every man:
prologue.children[5].stringValue // They sell the pasture now to buy the horse,
}
8 找到列表中最大或最小值
//Find the minimum of an array of Ints
[10,-22,753,55,137,-1,-279,1034,77].sort().first
[10,-22,753,55,137,-1,-279,1034,77].reduce(Int.max, combine: min)
[10,-22,753,55,137,-1,-279,1034,77].minElement()
//Find the maximum of an array of Ints
[10,-22,753,55,137,-1,-279,1034,77].sort().last
[10,-22,753,55,137,-1,-279,1034,77].reduce(Int.min, combine: max)
[10,-22,753,55,137,-1,-279,1034,77].maxElement()
9 并行操作
该特性在swift并不可行，但是可以使用GCD来构建。
10 Sieve of Erathostenes
reversed
11 不适用临时变量进行交换两个数
除了加减法，乘数法和异或法，swift只需要元组即可简单实现.......
var a=1,b=2
(a,b) = (b,a)
a //2
b //1
