ios - 如何在swift3中用其他元素替换数组的值？

Question

我有一个数组A，其中包含2个数组:

[[Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday], [Monday, Wednesday]]

现在我想用以下命令替换数组A的元素:

[[Sun, Mon, Tue, Wed, Thu, Fri, Sat], [Mon, Wed]]

为此，我打算使用:

for days in operatingDays {
  for weekdays in days
  {
  if (operatingDays[i] as? String == "Sun") {
    operatingDays[i] = "Su"
  } else if operatingDays[i] as? String == "Mon"{
    operatingDays[i] = "Mo"
  } else if operatingDays[i] as? String == "Tue"{
    operatingDays[i] = "Tu"
  } else if operatingDays[i] as? String == "Wed"{
    operatingDays[i] = "We"
  } else if operatingDays[i] as? String == "Thu"{
    operatingDays[i] = "Th"
  } else if operatingDays[i] as? String == "Fri"{
    operatingDays[i] = "Fr"
  } else if operatingDays[i] as? String == "Sat"{
    operatingDays[i] = "Sa"
  }
}
}

但是它显示了错误:

但是如何在Swift3中实现这一点将不胜感激。

Answer 1

var input = [["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"], ["Monday", "Wednesday"]]

var output = [[String]]()

for array in input {
    output.append(array.map {String($0.characters.prefix(3))})
}

输出将包含 [["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"], ["Mon", "Wed"]]