gistfile1.m

- (UIImage*)getImageFromURL {
    NSURL *url = [NSURL URLWithString:@"http://storm8.com/image.png"];
    return [UIImage imageWithData: [NSData dataWithContentsOfURL:url]]; 
}

- (void)saveImage: (UIImage*)image
{
    if (image != nil)
    {
      
        NSFileManager *fm = [NSFileManager ...]
  
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                      NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString* path = [documentsDirectory stringByAppendingPathComponent: 
                       [NSString stringWithString: @"image.png"] ];

        if ( ![fm fileExistsAtPath: path] ) {
          // save your image here using savedImagePath
          exit;
        }
        NSData* data = UIImagePNGRepresentation(image);
        [data writeToFile:path atomically:YES];
    }
}

- (UIImage*)loadImage
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                      NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString* path = [documentsDirectory stringByAppendingPathComponent: 
                      [NSString stringWithString: @"test.png"] ];
    UIImage* image = [UIImage imageWithContentsOfFile:path];
    return image;
}