How to easily resize/optimize an image size with iOS?

Question

My application is downloading a set of image files from the network, and saving them to the local iPhone disk. Some of those images are pretty big in size (widths larger tha

Answer 1

A couple of suggestions are provided as answers to this question. I had suggested the technique described in this post, with the relevant code:

+ (UIImage*)imageWithImage:(UIImage*)image 
               scaledToSize:(CGSize)newSize;
{
   UIGraphicsBeginImageContext( newSize );
   [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
   UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   return newImage;
}

As far as storage of the image, the fastest image format to use with the iPhone is PNG, because it has optimizations for that format. However, if you want to store these images as JPEGs, you can take your UIImage and do the following:

NSData *dataForJPEGFile = UIImageJPEGRepresentation(theImage, 0.6);

This creates an NSData instance containing the raw bytes for a JPEG image at a 60% quality setting. The contents of that NSData instance can then be written to disk or cached in memory.