访问 Wunderground API 的 "dailysummary" 部分时出现问题

Question

我创建了一组函数来从 Wunderground API 检索数据。但是，由于 "dailysummary" 部分以某种方式包含在数组中，我不知道如何访问它。这是我无法访问的部分：

"history": {
    "dailysummary": [
     { "date": {
     "pretty": "12:00 PM PDT on August 12, 2015",
    "year": "2015",
    "mon": "08",
    "mday": "12",
    "hour": "12",
    "min": "00",
    "tzname": "America/Los_Angeles"
    },
    "fog":"0","rain":"0","snow":"0","snowfallm":"0.00","snowfalli":"0.00","monthtodatesnowfallm":"", "monthtodatesnowfalli":"","since1julsnowfallm":"", "since1julsnowfalli":"","snowdepthm":"", "snowdepthi":"","hail":"0","thunder":"0","tornado":"0","meantempm":"26", "meantempi":"79","meandewptm":"16", "meandewpti":"60","meanpressurem":"1014", "meanpressurei":"29.94","meanwindspdm":"9", "meanwindspdi":"5","meanwdire":"","meanwdird":"331","meanvism":"16", "meanvisi":"10","humidity":"","maxtempm":"33", "maxtempi":"91","mintempm":"19", "mintempi":"66","maxhumidity":"78","minhumidity":"34","maxdewptm":"17", "maxdewpti":"62","mindewptm":"15", "mindewpti":"59","maxpressurem":"1016", "maxpressurei":"30.01","minpressurem":"1012", "minpressurei":"29.88","maxwspdm":"24", "maxwspdi":"15","minwspdm":"0", "minwspdi":"0","maxvism":"16", "maxvisi":"10","minvism":"16", "minvisi":"10","gdegreedays":"28","heatingdegreedays":"0","coolingdegreedays":"14","precipm":"0.00", "precipi":"0.00","precipsource":"","heatingdegreedaysnormal":"0","monthtodateheatingdegreedays":"0","monthtodateheatingdegreedaysnormal":"0","since1sepheatingdegreedays":"","since1sepheatingdegreedaysnormal":"","since1julheatingdegreedays":"0","since1julheatingdegreedaysnormal":"17","coolingdegreedaysnormal":"5","monthtodatecoolingdegreedays":"106","monthtodatecoolingdegreedaysnormal":"69","since1sepcoolingdegreedays":"","since1sepcoolingdegreedaysnormal":"","since1jancoolingdegreedays":"600","since1jancoolingdegreedaysnormal":"280" }
    ]
}

有关我如何调用 API 的参考，请参阅此站点：http://devdactic.com/rest-api-parse-json-swift/

Answer 1

您可能正在使用 SwiftyJSON 或其他库，但对于我的示例，我只是使用 NSJSONSerialization.

在这里，我进入 "history" 字典，然后进入 "dailysummary" 字典，并将结果转换为字典数组（假设您的 JSON 字典名为 "json" 也是）：

if let json = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &err) as? [String:AnyObject] {
    if let history = json["history"] as? [String:AnyObject],
        let daily = history["dailysummary"] as? [[NSObject:AnyObject]] {
        // "daily" is our array
    }
}

然后我在数组中循环（在你的例子中，里面只有一个对象，但可能有很多）：一些值是字符串，其他是字典，比如 "date".

我正在使用 "if let" 来安全地展开和投射内容：

if let json = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: &err) as? [String:AnyObject] {
    if let history = json["history"] as? [String:AnyObject],
        let daily = history["dailysummary"] as? [[NSObject:AnyObject]] {
        for item in daily {
            for (key, _) in item {
                println(key) // "mintempm", "mindewpti", "since1sepheatingdegreedaysnormal", "meantempm", etc
            }
            if let coolingdegreedaysnormal = item["coolingdegreedaysnormal"] as? String {
                println(coolingdegreedaysnormal) // "5"
            }
            if let date = item["date"] as? [String:AnyObject], let pretty = date["pretty"] as? String  {
                println(pretty) // "12:00 PM PDT on August 12, 2015"
            }
        }
    }
}

如果您使用的是 SwiftyJSON 或等效工具，则不必手动进行强制转换，但您必须使用特定于库的语法，也许是这种风格的语法：

for item in json["history"]["dailysummary"].array {
    // ...
}

访问 Wunderground API 的 "dailysummary" 部分时出现问题

Issues Accessing "dailysummary" section of Wunderground API

wunderground

swift