[TIMOB-27209] iOS: Be able to determine dark / light mode, as well as changes on it

   
   var currentStyle = Ti.App.iOS.userInterfaceStyle;
   
   console.log('Initial style:' + formattedUserInterfaceStyle(currentStyle));
   
   var win = Ti.UI.createWindow({
       backgroundColor: '#fff'
   });
   
   var btn = Ti.UI.createButton({
       title: 'Check User Interface Style'
   });
   
   btn.addEventListener('click', function() {
       Ti.API.info('User Interface Style: ' + formattedUserInterfaceStyle(currentStyle));
   });
   
   Ti.App.iOS.addEventListener('traitcollectionchange', function (event) {
       if (currentStyle !== Ti.App.iOS.userInterfaceStyle) {
           currentStyle = Ti.App.iOS.userInterfaceStyle;
           Ti.API.info('User Interface Style changed: ' + formattedUserInterfaceStyle(currentStyle));
       }
   });
   
   win.add(btn);
   win.open();
   
   function formattedUserInterfaceStyle(style) {
       switch (style) {
           case Ti.App.iOS.USER_INTERFACE_STYLE_LIGHT: return 'Light';
           case Ti.App.iOS.USER_INTERFACE_STYLE_DARK: return 'Dark';
       }
   
       return 'Unspecified';
   }