Update README with an usage example

README.md

@@ -1,13 +1,58 @@
 # ICNS parser
 
-Library for parsing [ICNS](https://en.wikipedia.org/wiki/Apple_Icon_Image_format) files.
+Library for parsing Apple [ICNS](https://en.wikipedia.org/wiki/Apple_Icon_Image_format) files.
 
 ## Install
 
 ```
 composer require proget-hq/icns-parser
 ```
 
+## Usage example
+
+The following code will parse icns files, display the formats found inside and extract all readable images to png files.
+
+```
+/**
+ * composer require intervention/image
+ */
+
+require_once('vendor/autoload.php');
+
+use Proget\IcnsParser\IcnsParser;
+use Intervention\Image\ImageManager;
+use Intervention\Image\Exception\NotReadableException;
+
+$parser = new IcnsParser();
+$manager = new ImageManager([/*'driver' => 'imagick'*/]);
+
+$iconFiles = ['AppIcon.icns'];
+
+foreach ($iconFile as $iconFile) {
+	echo '# Parsing '.$iconFile.''.PHP_EOL;
+	$r = $parser->parse($iconFile);
+
+	$elements = $r->elements();
+	echo 'Found '.count($elements).' elements:'.PHP_EOL;
+
+	usort($elements, fn($a, $b) => $a->type() <=> $b->type());
+	foreach ($elements as $element) {
+		echo ' - '.$element->type().''.PHP_EOL;
+
+		try {
+			$img = $manager->make($element->data());
+			echo '   read '.$img->mime().' '.$img->width().'x'.$img->width().PHP_EOL;
+
+			$img->save($iconFile.'-'.$element->type().'.png');
+			echo '   wrote to '.$iconFile.'-'.$element->type().'.png'.PHP_EOL;
+		} catch (NotReadableException $e) {
+			echo '   could not read'.PHP_EOL;
+		}
+	}
+}
+
+```
+
 ## License
 
 MIT