Easy to initialize the output zip file.

src/PhpZip/ZipFile.php

@@ -157,6 +157,13 @@ class ZipFile implements \Countable, \ArrayAccess, \Iterator, ZipConstants
         return $zipFile;
     }
 
+    /**
+     * @return ZipOutputFile
+     */
+    public function edit(){
+        return ZipOutputFile::openFromZipFile($this);
+    }
+
     /**
      * Check zip file signature
      *

src/PhpZip/ZipOutputFile.php

@@ -152,6 +152,22 @@ class ZipOutputFile implements \Countable, \ArrayAccess, \Iterator, ZipConstants
         return new self($zipFile);
     }
 
+    /**
+     * Open zip file from update.
+     *
+     * @param string $filename
+     * @return ZipOutputFile
+     * @throws IllegalArgumentException
+     * @see ZipOutputFile::__construct()
+     */
+    public static function openFromFile($filename)
+    {
+        if (empty($filename)) {
+            throw new IllegalArgumentException("Zip file is null");
+        }
+        return new self(ZipFile::openFromFile($filename));
+    }
+
     /**
      * Count zip entries.
      *