Android Custom Fonts

First we must rename our font files by using lowercase only and replacing - with _ for example:
```
Quicksand-Bold.ttf      ->   quicksand_bold.ttf
Quicksand-Light.ttf     ->   quicksand_light.ttf
Quicksand-Medium.ttf    ->   quicksand_medium.ttf
Quicksand-Regular.ttf   ->   quicksand_regular.ttf
Quicksand-SemiBold.ttf  ->   quicksand_semibold.ttf
```
Copy renamed file to android/app/src/main/res/font

Create and .xml file and named it same as your font name for example quicksand.xml and put it in the same directory:

<?xml version="1.0" encoding="utf-8"?>
<font-family xmlns:app="http://schemas.android.com/apk/res-auto">
   <font app:fontStyle="normal" app:fontWeight="100" app:font="@font/quicksand_thin" />
   <font app:fontStyle="italic" app:fontWeight="100" app:font="@font/quicksand_thinitalic"/>
   <font app:fontStyle="normal" app:fontWeight="200" app:font="@font/quicksand_extralight" />
   <font app:fontStyle="italic" app:fontWeight="200" app:font="@font/quicksand_extralightitalic"/>
   <font app:fontStyle="normal" app:fontWeight="300" app:font="@font/quicksand_light" />
   <font app:fontStyle="italic" app:fontWeight="300" app:font="@font/quicksand_lightitalic"/>
   <font app:fontStyle="normal" app:fontWeight="400" app:font="@font/quicksand_regular" />
   <font app:fontStyle="italic" app:fontWeight="400" app:font="@font/quicksand_italic"/>
   <font app:fontStyle="normal" app:fontWeight="500" app:font="@font/quicksand_medium" />
   <font app:fontStyle="italic" app:fontWeight="500" app:font="@font/quicksand_mediumitalic"/>
   <font app:fontStyle="normal" app:fontWeight="600" app:font="@font/quicksand_semibold" />
   <font app:fontStyle="italic" app:fontWeight="600" app:font="@font/quicksand_semibolditalic"/>
   <font app:fontStyle="normal" app:fontWeight="700" app:font="@font/quicksand_bold" />
   <font app:fontStyle="italic" app:fontWeight="700" app:font="@font/quicksand_bolditalic"/>
   <font app:fontStyle="normal" app:fontWeight="800" app:font="@font/quicksand_extrabold" />
   <font app:fontStyle="italic" app:fontWeight="800" app:font="@font/quicksand_extrabolditalic"/>
   <font app:fontStyle="normal" app:fontWeight="900" app:font="@font/quicksand_black" />
   <font app:fontStyle="italic" app:fontWeight="900" app:font="@font/quicksand_blackitalic"/>
</font-family>

For newer Android versions v26:

Create android/app/src/main/res/font-v26.
Add only .xml file without font files for example quicksand.xml.
Use same example above and replace app: with android: for example:

---<font-family xmlns:app="http://schemas.android.com/apk/res-auto">
+++<font-family xmlns:android="http://schemas.android.com/apk/res/android">

---<font app:fontStyle="normal" app:fontWeight="100" app:font="@font/quicksand_thin" />
+++<font android:fontStyle="normal" android:fontWeight="100" android:font="@font/quicksand_thin" />

For Java go to android/app/src/main/java/com/<yourAppName>/MainApplication.java

// ---
import com.facebook.react.views.text.ReactFontManager; // import this
// ---

public class MainApplication extends Application implements ReactApplication {
   @Override
   public void onCreate() {
     super.onCreate();
    // add the following line after (super.onCreate)
     ReactFontManager.getInstance().addCustomFont(this, "Quicksand", R.font.quicksand);
// ---

For Kotlin go to android/app/src/main/java/com/<yourAppName>/MainApplication.kt

// ---
import com.facebook.react.common.assets.ReactFontManager // import this
// ---

class MainApplication : Application(), ReactApplication {
  // ---
    override fun onCreate() {
        super.onCreate()
        // add the following line after (super.onCreate)
        ReactFontManager.getInstance().addCustomFont(this, "Quicksand", R.font.quicksand)
// ---

Use the font:

const style = createStyleSheet.create({
  text: {
    fontFamily: "Quicksand",
  },
});

Rebuild and test.