一个天气预报APP至少应该具备以下功能：
*可以罗列出全国所有的省、市、县；
*可以查看全国任意城市的天气信息；
*可以自由的切换城市，去查看其他城市的天气；
*提供手动更新以及后台自动更新天气的功能；
这里使用和风天气作为天气预报来源，全国省市县的数据信息这里使用的是《第一行代码》的作者郭霖大佬架设的服务器。
具体就是：想要罗列出中国所有的省份，只需要访问这个地址：http://guolin.tech/api/china，服务器会返回一段JSON格式的数据，其中包括了中国所有省份的名称及省份的id：
[{"id":1,"name":"北京"},{"id":2,"name":"上海"},{"id":3,"name":"天津"},
{"id":4,"name":"重庆"},{"id":5,"name":"香港"},{"id":6,"name":"澳门"},
{"id":7,"name":"台湾"},{"id":8,"name":"黑龙江"},{"id":9,"name":"吉林"},
{"id":10,"name":"辽宁"},{"id":11,"name":"内蒙古"},{"id":12,"name":"河北"},
{"id":13,"name":"河南"},{"id":14,"name":"山西"},{"id":15,"name":"山东"},
{"id":16,"name":"江苏"},{"id":17,"name":"浙江"},{"id":18,"name":"福建"},
{"id":19,"name":"江西"},{"id":20,"name":"安徽"},{"id":21,"name":"湖北"},
{"id":22,"name":"湖南"},{"id":23,"name":"广东"},{"id":24,"name":"广西"},
{"id":25,"name":"海南"},{"id":26,"name":"贵州"},{"id":27,"name":"云南"},
{"id":28,"name":"四川"},{"id":29,"name":"西藏"},{"id":30,"name":"陕西"},
{"id":31,"name":"宁夏"},{"id":32,"name":"甘肃"},{"id":33,"name":"青海"},
{"id":34,"name":"新疆"}]
如果想要河北省有那些城市，就把id加上：http://guolin.tech/api/china/12
[{"id":57,"name":"石家庄"},{"id":58,"name":"保定"},{"id":59,"name":"张家口"},
{"id":60,"name":"唐山"},{"id":61,"name":"廊坊"},{"id":62,"name":"沧州"},
{"id":63,"name":"衡水"},{"id":64,"name":"邢台"},{"id":65,"name":"邯郸"},
{"id":66,"name":"秦皇岛"}]
如果想要知道秦皇岛有那些县，就再加上id：http://guolin.tech/api/china/12/66
[{"id":557,"name":"秦皇岛","weather_id":"CN101091101"},{"id":558,"name":"青龙","weather_id":"CN101091102"},
{"id":559,"name":"昌黎","weather_id":"CN101091103"},{"id":560,"name":"抚宁","weather_id":"CN101091104"},
{"id":561,"name":"卢龙","weather_id":"CN101091105"},{"id":562,"name":"北戴河","weather_id":"CN101091106"}]
以上是全国省市县的数据，然后是天气数据的api的使用：
https://free-api.heweather.com/v5/weather?city=yourcity&key=yourkey
这是一个免费的使用方法，一天可以访问4000次，不过要先申请。yourcity部分就填之前获取到的id即可，key的话申请就有了。
https://free-api.heweather.com/v5/weather?city=CN101091101&key=32d1c829ed7d483086f4f5b4d5947cef
这样就能查询到秦皇岛的天气情况，返回的数据就比较复杂了，官方的例子就是：
{ "HeWeather5": [ { "alarms": [ { "level": "蓝色", "stat": "预警中", "title": "山东省青岛市气象台发布大风蓝色预警", "txt": "青岛市气象台2016年08月29日15时24分继续发布大风蓝色预警信号：预计今天下午到明天，我市北风风力海上6到7级阵风9级，陆地4到5阵风7级，请注意防范。", "type": "大风" } ], "aqi": { "city": { "aqi": "60", "co": "0", "no2": "14", "o3": "95", "pm10": "67", "pm25": "15", "qlty": "良", //共六个级别，分别：优，良，轻度污染，中度污染，重度污染，严重污染 "so2": "10" } }, "basic": { "city": "青岛", "cnty": "中国", "id": "CN101120201", "lat": "36.088000", "lon": "120.343000", "prov": "山东" //城市所属省份（仅限国内城市） "update": { "loc": "2016-08-30 11:52", "utc": "2016-08-30 03:52" } }, "daily_forecast": [ { "astro": { "mr": "03:09", "ms": "17:06", "sr": "05:28", "ss": "18:29" }, "cond": { "code_d": "100", "code_n": "100", "txt_d": "晴", "txt_n": "晴" }, "date": "2016-08-30", "hum": "45", "pcpn": "0.0", "pop": "8", "pres": "1005", "tmp": { "max": "29", "min": "22" }, "vis": "10", "wind": { "deg": "339", "dir": "北风", "sc": "4-5", "spd": "24" } } ], "hourly_forecast": [ { "cond": { "code": "100", "txt": "晴" }, "date": "2016-08-30 12:00", "hum": "47", "pop": "0", "pres": "1006", "tmp": "29", "wind": { "deg": "335", "dir": "西北风", "sc": "4-5", "spd": "36" } } ], "now": { "cond": { "code": "100", "txt": "晴" }, "fl": "28", "hum": "41", "pcpn": "0", "pres": "1005", "tmp": "26", "vis": "10", "wind": { "deg": "330", "dir": "西北风", "sc": "6-7", "spd": "34" } }, "status": "ok", "suggestion": { "comf": { "brf": "较舒适", "txt": "白天天气晴好，您在这种天气条件下，会感觉早晚凉爽、舒适，午后偏热。" }, "cw": { "brf": "较不宜", "txt": "较不宜洗车，未来一天无雨，风力较大，如果执意擦洗汽车，要做好蒙上污垢的心理准备。" }, "drsg": { "brf": "热", "txt": "天气热，建议着短裙、短裤、短薄外套、T恤等夏季服装。" }, "flu": { "brf": "较易发", "txt": "虽然温度适宜但风力较大，仍较易发生感冒，体质较弱的朋友请注意适当防护。" }, "sport": { "brf": "较适宜", "txt": "天气较好，但风力较大，推荐您进行室内运动，若在户外运动请注意防风。" }, "trav": { "brf": "适宜", "txt": "天气较好，风稍大，但温度适宜，是个好天气哦。适宜旅游，您可以尽情地享受大自然的无限风光。" }, "uv": { "brf": "强", "txt": "紫外线辐射强，建议涂擦SPF20左右、PA++的防晒护肤品。避免在10点至14点暴露于日光下。" } } } ] }