SWIFT

dart capitalize first letter of each word

extension CapExtension on String {
  String get inCaps => '${this[0].toUpperCase()}${this.substring(1)}';
  String get allInCaps => this.toUpperCase();
  String get capitalizeFirstofEach => this.split(" ").map((str) => str.capitalize).join(" ");
}

final helloWorld = 'hello world'.inCaps; // 'Hello world'
final helloWorld = 'hello world'.allInCaps; // 'HELLO WORLD'
final helloWorld = 'hello world'.capitalizeFirstofEach; // 'Hello World'

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();