Upload pictures to my app - objective-c

Question

I´m designing a new app for an iPad. This app will work with a barcode scanner, and when it scans a code, it will show an image asociated.
I was thinking to build that asociating de barcode to an image name for example:
- Barcode 09090909 will show 09090909.png picture
- Barcode 19191919 will show 19191919.png picture
....
I think that there is no problem with that, but the problem comes when I need to add new barcode/pictures to the app. How can I send a new picture to my App? I see that when you develop on XCode and build you App, all the data goes into de App.
Any help or clue? thanks in advance

Answer 1

You can simple load them on the fly from your server, but then a network connection is required. To load them async from an server you can use this code:
dispatch_queue_t image_queue = dispatch_queue_create("com.company.app.imageQueue", NULL);
dispatch_queue_t main_queue = dispatch_get_main_queue();
dispatch_async(image_queue, ^{
NSString *URLString = #"http://example.com/images/19191919.png";
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:URLString];
UIImage *image = [UIImage imageWithData:imageData];
dispatch_async(main_queue, ^{
[imageView setImage:image];
});
});
If you want you can also save the image to the cache dir (using the document dir is not recommended because it will collide with Apples iOS Data Storage Guidelines) and check before downloading an image twice, then the code will look like this:
NSString *fileName = #"19191919.png";
NSString *URLBaseString = #"http://example.com/images/";
NSString *URLString = [URLBaseString stringByAppendingString:fileName];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cachePath = [paths objectAtIndex:0];
NSString *dataPath = [cachePath stringByAppendingPathComponent:fileName];
NSFileManager *fileManager = [NSFileManager defaultManager];
if ( [fileManager fileExistsAtPath:dataPath] )
{
UIImage *image = [UIImage imageWithContentsOfFile:dataPath];
[imageView setImage:image];
}
else
{
dispatch_async(image_queue, ^{
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:URLString];
UIImage *image = [UIImage imageWithData:imageData];
[UIImagePNGRepresentation(image) writeToFile:dataPath atomically:YES];
dispatch_async(main_queue, ^{
[imageView setImage:image];
});
});
}
This code has not been tested, but should work. Note that I'm relying on ARC to manage memory.