Swift 2.0

1.打印

print("")

2.数组contains

let arr = ["a","b","c","d","e"]
if arr.contains("a"){
}

3.获取字符串count

let str  = "angelababy love"
let count = str.characters.count

4.do while改变

var count = 0
repeat{
  print(count)
  count++
}while count <= 10

5.guard

func todo(name:String?,age:Int?){
  guard let myName = name else{
    return
  }
  guard let myAge = age else{
    return
  }
  print("MyName:\(myName),MyAge:\(myAge)")
}

用于简化如下swift1.2中过多的嵌套，gurad 后面表达式返回值是Bool类型

func todo(name:String?,age:Int?){
  if let myName = name{
   if let myAge = age{
     print("MyName:\(myName),MyAge:\(myAge)")
    }else{
      return
    }
  }else{
    return
  }
}

6.异常处理

enum MyError: ErrorType { 
  case NotExist 
}
func todo(name:String?) throws -> String{
  guard let myName = name else{
    throw  MyError.NotExist
  }
  return myName
}

这里有两种处理
①

do{
  let name = try todo("john")
  print(name)
}catch{
  print(error)
}

**这个结果是 **

"john"

②

let name = try? todo("john"))
print(name)

**这个结果是 **

Optional("john")