# Use platform-specific network features
{% hint style="warning" %}
This section is relevant for building [Wisej.NET Hybrid **local** applications](https://docs.wisej.com/hybrid/development/local-application) that are running locally on the device. Wisej.NET Hybrid remote applications cannot directly interact with platform-specific features except through a [**bridge**](https://docs.wisej.com/hybrid/advanced/custom-handler).
{% endhint %}
The **HttpClient** class provides an abstraction of the connection to the network. An app that uses this class is independent of the native platform networking stack. The Wisej.NET Hybrid (.NET MAUI) templates map the **HttpClient** class to code that utilizes the native networking stack of each platform. This enables an application to take advantage of platform-specific network configuration and optimization features. This is especially important when you need to configure a client application to connect securely to a REST web service.
## Configure App Transport Security on iOS
App Transport Security (ATS) is an iOS feature that requires every network communication done through the native HTTP network stack to use TLS 1.2 or above. Modern encryption algorithms won't disclose information if one of the long-term keys is compromised.
If your app doesn't adhere to these rules, it will be denied network access. To fix this problem, you have two options; you can change your endpoint to adhere to the App Transport Security policy or you can opt out of App Transport Security.
To opt out of App Transport Security, add a new key called `NSAppTransportSecurity` to the **Info.plist** file. You'll find the **Info.plist** file in the **iOS** folder in project's the **Platforms** folder in Solution Explorer. This key is actually a dictionary. Add another key called `NSExceptionDomains` to this dictionary. This key contains a child for each of the endpoints you want to target. Each endpoint can have its own configuration, specifying which features to allow or disallow. You can add this key either using the generic plist editor in Visual Studio, or by opening it as an XML file.
Here's an example configuration for one endpoint shown as XML:
```xml
NSAppTransportSecurity
NSExceptionDomains
dotnet.microsoft.com
NSExceptionMinimumTLSVersion
TLSv1.0
NSExceptionAllowsInsecureHTTPLoads
```
This example adds an exception to the endpoint at **dotnet.microsoft.com**. If you're debugging a service locally on your development machine, you can opt out of App Transport Security for local traffic with the `NSAllowsLocalNetworking` key as follows:
```xml
NSAppTransportSecurity
NSAllowsLocalNetworking
```
If you can't identify all your endpoints, disable App Transport Security for all unspecified endpoints by using the `NSAllowsArbitraryLoads` key:
```xml
NSAppTransportSecurity
NSAllowsArbitraryLoads
```
There are other options that you can add to be more specific about how you want to opt out. Further guidance is outside the scope of this module.
## Configure Android Network security
Like iOS, Android has a similar security model around network communication. This model was introduced with Android 9 (API level 28). Clear text (non-HTTPS) traffic is disabled by default when your application targets Android 9 (API Level 28) or higher. This policy might affect your development cycle if your app needs to download an image or file on a server that hasn’t been configured for HTTPS. Also, you might just be trying to debug your application locally and don’t want to install development certificates. You might have strong business requirements that all web traffic on all versions of Android is always HTTPS. The Network Security Configuration feature of Android allows you to finely tune network traffic security in an app.
#### Permit clear text traffic
To permit clear text traffic, create a new XML file in the **Resources/xml** folder named **network\_security\_config.xml** (You might also need to create the **xml** folder). The **Resources** folder is in the **Android** platform folder in Solution Explorer. Inside this file, add a `network-security-config` element with a `domain-config` child element. The following configuration enables clear text traffic for a specific domain and for an IP address:
```xml
10.0.2.2
microsoft.com
```
You can strengthen your app's security by restricting clear text traffic on all versions of Android regardless of the target framework. You do this by setting the `cleartextTrafficPermitted` property of the `domain-config` element to `false`. This configuration setting blocks all non-HTTPS traffic.
For the app to recognize the **network\_security\_config.xml** file, configure the `networkSecurityConfig` property for the `application` node in the **AndroidManifest.xml** located in the **Properties** folder:
```xml
```
You can specify additional options if you need to be more specific about how you want to opt out of transport security.
## Debug apps locally
An important benefit of building mobile applications with Visual Studio is the ability to run and debug mobile applications using the iOS Simulator or Android emulator. These apps can consume ASP.NET Core web services that are running locally and exposed over HTTP.
Applications running in the iOS Simulator can connect to local HTTP web services using your machine's IP address, or via the **localhost** hostname. The application must opt out of ATS specifying a minimum of `NSAllowsLocalNetworking`. For example, given a local HTTP web service that exposes a `GET` operation via the **/api/todoitems/** relative URI, an application running in the iOS Simulator can consume the operation by sending a `GET` request to **/api/todoitems/**.
Applications running in the Android emulator can connect to local HTTP web services through the 10.0.2.2 address. This address is an alias for the host loopback interface (127.0.0.1 on your development machine). A network-security configuration must also be set up for this specific IP address. For example, given a local HTTP web service that exposes a `GET` operation via the **/api/todoitems/** relative URI, an application running in the Android emulator can consume the operation by sending a `GET` request to [**http://10.0.2.2:/api/todoitems/**](http://10.0.2.2/api/todoitems/).
Note
ASP.NET Core web services running under test on the local host must disable HTTPS redirects by commenting out the statement `app.UseHttpsRedirection();` in the **Startup.cs** file.
## Detect the operating system
An app can determine on which platform it's running by using the `DeviceInfo` class. In the following example, the application sets the **BaseAddress** variable to a different value, depending on whether it's running on Android:
```csharp
public static string BaseAddress = DeviceInfo.Platform == DevicePlatform.Android ? "http://10.0.2.2:5000" : "http://localhost:5000";
public static string TodoItemsUrl = $"{BaseAddress}/api/todoitems/";
```
{% embed url="" %}
Source Material
{% endembed %}