我正在关注RWtutorialtolearnaboutSwift我在以下函数声明的第一行遇到错误:funcreturnPossibleTips()->[Int:Double]{letpossibleTipsInferred=[0.15,0.18,0.20]letpossibleTipsExplicit:[Double]=[0.15,0.18,0.20]varretval=[Int:Double]()forpossibleTipinpossibleTipsInferred{letintPct=Int(possibleTip*100)retval[intPct]=calcTipWithTi

我正在关注RWtutorialtolearnaboutSwift我在以下函数声明的第一行遇到错误:funcreturnPossibleTips()->[Int:Double]{letpossibleTipsInferred=[0.15,0.18,0.20]letpossibleTipsExplicit:[Double]=[0.15,0.18,0.20]varretval=[Int:Double]()forpossibleTipinpossibleTipsInferred{letintPct=Int(possibleTip*100)retval[intPct]=calcTipWithTi