flutter/如何使用共享首选项保存地理点

Question

我想知道如何在我的flutter应用程序中使用共享首选项保存用户的地理点。它有两个值(lat，long(，但下面的代码是我所能写的，但没有起作用。

static String sharedPreferenceUserGeopointKey = "USERGEOPOINTKEY";
static Future<bool> saveUserGeopointSharedPreference(var geopoint) async {
SharedPreferences preferences = await SharedPreferences.getInstance();
return await preferences.setDouble(
sharedPreferenceUserGeopointKey, geopoint);
}

后来我像这样检索这些数据；

static Future<dynamic> getUserGeopointSharedPreference() async {
SharedPreferences preferences = await SharedPreferences.getInstance();
double mylat = 
preferences.getDouble(sharedPreferenceUserGeopointLatKey);
double mylong = 
preferences.getDouble(sharedPreferenceUserGeopointLongKey);
return true;
}
bool result = await getUserGeopointSharedPreferences();
GeoPoint geopoint = result;

我无法将result放入GeoPoint类型的地理点对象中，我可以这样做吗？

Answer 1

您需要用不同的键调用两次setDouble

或者尝试使用共享首选项类的setStringList((方法
在这种情况下，您需要将双纬度、logitude更改为列表字符串

static String sharedPreferenceUserGeopointLatitudeKey = "USERGEOPOINT_LATITUDE_KEY";
static String sharedPreferenceUserGeopointLogitudeKey = "USERGEOPOINT_LONGITUDE_KEY";
static Future<bool> saveUserGeopointSharedPreference(var lat, var long) async {
SharedPreferences preferences = await SharedPreferences.getInstance();
await preferences.setDouble(
sharedPreferenceUserGeopointLatitudeKey, lat);
await preferences.setDouble(
sharedPreferenceUserGeopointLogitudeKey, long);
return true
}

static Future<GeoPoint> getUserGeopointSharedPreference() async {
SharedPreferences preferences = await SharedPreferences.getInstance();
double mylat = 
preferences.getDouble(sharedPreferenceUserGeopointLatKey);
double mylong = 
preferences.getDouble(sharedPreferenceUserGeopointLongKey);
return GeoPoint.fromLatLng(name: 'Position', point: LatLng(mylat, mylong);
}
GeoPoint geopoint = await getUserGeopointSharedPreferences();