CODE EXAMPLE FOR SWIFT

Capitalize first letter in Flutter | Dart

// string_extension.dart
extension StringExtension on String {
    String capitalize() {
      return "${this[0].toUpperCase()}${this.substring(1).toLowerCase()}";
    }
}

// in the file you want to use the extension 
import "string_extension.dart";

var someCapitalizedString = "someString".capitalize();