swift - 仅当键在字典中可用时才获取数据

Question

我有以下类型的字典:

{
  "filter": {
    "year_option": {
      "2015": "2015",
      "2016": "2016"
    },
    "month_option": {
      "10": "Oct",
      "11": "Nov",
      "12": "Dec",
      "01": "Jan",
      "02": "Feb",
      "03": "Mar",
      "04": "Apr",
      "05": "May",
      "06": "Jun",
      "07": "Jul",
      "08": "Aug",
      "09": "Sept"
    }
  }
}

这是来自 API 的响应。 字典中的键可能因每个用户而异。那么有没有办法仅在键可用时获取Dictionary值？

Answer 1

当然，有办法。使用 if let 检查是否存在 key 。 例如:

if let key1 = yourDict["key1"] {
   // do something with key1
}

使用您的示例:

if let filter = yourDict["filter"] as? [String: Any] {
   if let yearOption = filter["year_option"] as? [String: String] {
      // there is the year_option JSON
   }
   if let monthOption = filter["month_option"] as? [String:String] {
      // there is the month option JSON
   }
}