How to Connect GATT Server in Xamarin iOS

In Xamarin Forms,

I want to know how the GATT server works with BLE for iOS.

Anyone can help how to connect GATT server with iOS.

I do think that it's a big question. You could refer to Bluetooth GATT Xamarin.Forms client and its related xamarin project. Generally, several steps should be taken

1. check the bluetooth-le status

2. scan the GATT server

3. connect the server

4. Get Service

5. Get Characteristic

According to the implementation and complete understanding of BLE(Bluetooth low energy) in Xamarin forms you should also add some keys and values in your info.plist

<key>UIBackgroundModes</key>
    <array>
        <string>bluetooth-central</string>
        <string>bluetooth-peripheral</string>
    </array>
<key>NSBluetoothPeripheralUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>
<key>NSBluetoothAlwaysUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>
<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>
<key>NSLocationAlwaysUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>
<key>NSLocationWhenInUseUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>

Also, you could refer to Bluetooth LE plugin for Xamarin & MAUI which might be useful for understanding.