[TIMOB-15247] iOS: Ti.Blob.imageAsResized always returns a png image

   // read source image
   var sourceImage = Titanium.Filesystem.getFile(Titanium.Filesystem.resourcesDirectory, 'source.jpg').read();
   
   // resize it using core Ti.Blob.imageAsResized()
   var resizedImage = sourceImage.imageAsResized(160,120);
   
   // do this step if ios only 
   if (OS_IOS)
   {
     // choose desired compression level (from 0.0 to 1.0) 
     var compression_level = 0.75; 
   
     // load ImageFactory module
     var ImageFactory = require('ti.imagefactory');
     
     // convert image to jpeg
     resizedImage = ImageFactory.compress( resizedImage, compression_level );    
   }
   
   // create destination file
   var destFile = Titanium.Filesystem.getFile(Titanium.Filesystem.applicationDataDirectory, 'destination.jpg');
   
   // write resized image to destination file
   destFile.write(resizedImage);
   

   var image = Titanium.Filesystem.getFile(Titanium.Filesystem.resourcesDirectory, 'srcImage.jpg').read();
   Ti.API.info("original image size:" + image.size);
   Ti.API.info("original image dimensions: " + image.width + 'x' + image.height);
   var newBlob1 = image.imageAsResized(160,120);
   Ti.API.info("test 1 image size:" + newBlob1.size);
   Ti.API.info("test 1 image dimensions: " + newBlob1.width + 'x' + newBlob1.height);
   
   var bgImage = Titanium.Filesystem.getFile(Titanium.Filesystem.applicationDataDirectory, 'test.jpg');
   
   bgImage.write(newBlob1);
   //
   // => Even though the output filename contains .jpg, it's a png file that is created (but named 'test.jpg')
   //
   // There's two ways to verify that it's a png file that has been created:
   // 1) the file is large (much larger than if it had been saved as jpeg)
   // 2) viewing the file with an "advanced" image viewer (like, for instance, IrfanView on Windows), one can check that the filetype is actually png rather than jpg
   //