[Xamarin]如何取得使用者的地理位置

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[Xamarin]如何取得使用者的地理位置

android專案的設定:
在androd專案底下的 \Properties\AssemblyInfo.cs加入下列內容

//加入讀取使用者位置的功能
[assembly: UsesPermission(Android.Manifest.Permission.AccessCoarseLocation)]
[assembly: UsesPermission(Android.Manifest.Permission.AccessFineLocation)]
[assembly: UsesFeature("android.hardware.location", Required = false)]
[assembly: UsesFeature("android.hardware.location.gps", Required = false)]
[assembly: UsesFeature("android.hardware.location.network", Required = false)]


ios的專案的設定:
Info.plist用文字編輯器打開,並且加入下面內容

<key>NSLocationWhenInUseUsageDescription</key>
<string>在這邊填寫入為什麼您需要存取使用者位置的權限.</string>
<key>UIBackgroundModes</key>
<array>
	<string>location</string>
</array>


上面是設定的部分,接下來是怎麼在程式碼中呼叫
然後於任何一個類別(例如你的商業邏輯.cs裡面),加入下面GetCurrentLocation()這個function,用來取得目前的使用者位置
ps.當你以同步的方式去呼叫GetCurrentLocation()的時候,GetCurrentLocation()的boolSetTimeout參數必須為true,隨便設定個3秒也可以

public static async Task<Location> GetCurrentLocation(bool boolSetTimeout = true,
	double timeoutMilliseconds = 1000)
{
	try
	{

		GeolocationRequest request;
		if (boolSetTimeout == true)
		{
			request = new GeolocationRequest(GeolocationAccuracy.High,
				TimeSpan.FromMilliseconds(timeoutMilliseconds));
		}
		else
		{
			request = new GeolocationRequest(GeolocationAccuracy.High);
		}

		if ((DateTime.Now - LatestGetLocationTime).TotalSeconds > 300
			|| LatestLocation == null)
		{
			//超過300秒就重新取目前位置                   
			var location = await Geolocation.GetLocationAsync(request);

			if (location != null)
			{
				//Console.WriteLine($"Latitude: {location.Latitude}, Longitude: {location.Longitude}, Altitude: {location.Altitude}");
				LatestLocation = location;
				LatestGetLocationTime = DateTime.Now;
				return location;

			}
		}
		else
		{
			//不然就取五分鐘之前的
			return LatestLocation;
		}


	}
	catch (FeatureNotSupportedException fnsEx)
	{
		// Handle not supported on device exception
	}
	catch (FeatureNotEnabledException fneEx)
	{
		// Handle not enabled on device exception
	}
	catch (PermissionException pEx)
	{
		// Handle permission exception
	}
	catch (Exception ex)
	{
		// Unable to get location
	}

	return null;
}


在.xaml.cs裡面要引用上面這個function的時候,像是下面這樣呼叫即可(下面這是以非同步的方式呼叫,建議使用非同步方式,盡量不要用同步的方式去call)

var currentLocation = await Utils.GetCurrentLocation(false);//目前所在位置
Console.WriteLine(currentLocation.Latitude);
Console.WriteLine(currentLocation.Longitude);


這篇大概是這樣……


參考資料:
Xamarin.Essentials:地理位置
https://docs.microsoft.com/zh-tw/xamarin/essentials/geolocation?tabs=ios
逐步解說-Xamarin 中的背景位置
https://docs.microsoft.com/zh-tw/xamarin/ios/app-fundamentals/backgrounding/ios-backgrounding-walkthroughs/location-walkthrough