Swift学习笔记（一）：基础

//隐式
let inferredTeam = 3
//显式
let explicitTeam:Int = 4

//通过\(变量或常量名)来引用组合字符串
println("\(inferredTeam) is bigger than \(variablesTeam)!")

// 类使用class关键字声明
class TipCalculator {
 
  // 在类中创建属性
  let total: Double
  let taxPct: Double
  let subtotal: Double
 
  // 属性必须在声明时赋予一个初始值，或者在initializer里，否则必须声明其为optional（这里使用的是initializer）
  init(total:Double, taxPct:Double) {
    self.total = total
    self.taxPct = taxPct
    subtotal = total / (taxPct + 1)
  }
 
  // 方法使用func关键字声明，返回Double类型
  func calcTipWithTipPct(tipPct:Double) -> Double {
    return subtotal * tipPct
  }
 
  // 无返回值方法
  func printPossibleTips() {
    println("15%: \(calcTipWithTipPct(0.15))")
    println("18%: \(calcTipWithTipPct(0.18))")
    println("20%: \(calcTipWithTipPct(0.20))")
  }
 
}
 
// 创建类实例对象，通过类实例对象调用类中的方法
let tipCalc = TipCalculator(total: 33.25, taxPct: 0.06)
tipCalc.printPossibleTips()

//1
let possibleTipsInferred = [0.15, 0.18, 0.20]
let possibleTipsExplicit:[Double] = [0.15, 0.18, 0.20]

//2
for possibleTip in possibleTipsInferred {
  println("\(possibleTip*100)%: \(calcTipWithTipPct(possibleTip))")
}
//3
for i in 0..<possibleTipsInferred.count {
  let possibleTip = possibleTipsInferred[i]
  println("\(possibleTip*100)%: \(calcTipWithTipPct(possibleTip))")
}

// 1
func returnPossibleTips() -> [Int: Double] {
 
  let possibleTipsInferred = [0.15, 0.18, 0.20]
  let possibleTipsExplicit:[Double] = [0.15, 0.18, 0.20]
 
  // 创建一个空字典
  var retval = Dictionary<Int, Double>()
  for possibleTip in possibleTipsInferred {
    let intPct = Int(possibleTip*100)
    // 赋值给字典
    retval[intPct] = calcTipWithTipPct(possibleTip)
  }
  return retval
 
}