Reading and writing images to an SQLite DB for iPhone use

Question

Hi All, I'm still new to iPhone Dev so be gentle.

I've set up a SQLite DB that currently reads and writes NSStrings perfectly. The only problem I have now is that I also want to store an image in the database and recall it later. I've read up a bit on using NSData and encoding the image but I'm not entirely sure what the syntax is for what I want to do. Any code snippets or examples would be greatly appreciated.

My current process goes like this: UIImagePickerController -> User Chooses Image from Photos -> chosenImage is set to instance of UIImageView -> Now I want to take this image and store it in the DB

Thanks in advance!

Edit* I should mention this call will eventually be replaced with a call to a remote server. Not sure if this makes a difference as far as performance goes.

Answer 1

One option (and generally preferred when working in SQL) is to write the image to a file on the system and store the path (or some other kind of identifier) in the database.

Answer 2

You'll need to convert the UIImage hosted within your UIImageView into a binary BLOB for storage in SQLite. To do that, you can use the following:

NSData *dataForImage = UIImagePNGRepresentation(cachedImage);
sqlite3_bind_blob(yourSavingSQLStatement, 2, [dataForImage bytes], [dataForImage length], SQLITE_TRANSIENT);

This will generate a PNG representation of your image, store it in an NSData instance, and then bind the bytes from the NSData as a BLOB for the second argument in your SQL query. Use UIImageJPEGRepresentation in the above to store in that format, if you like. You will need to have a BLOB column added to the appropriate table in your SQLite database.

To retrieve this image, you can use the following:

NSData *dataForCachedImage = [[NSData alloc] initWithBytes:sqlite3_column_blob(yourLoadingSQLStatement, 2) length: sqlite3_column_bytes(yourLoadingSQLStatement, 2)];    
self.cachedImage = [UIImage imageWithData:dataForCachedImage];
[dataForCachedImage release];

Answer 3

Brad's solution works perfectly =D

Thanks Brad

Answer 4

Writing Image to SQLite DB

if(myImage != nil){ NSData *imgData = UIImagePNGRepresentation(myImage); sqlite3_bind_blob(update_stmtement, 6, [imgData bytes], [imgData length], NULL);
} else { sqlite3_bind_blob(update_stmtement, 6, nil, -1, NULL); }

Reading From SQLite DB

NSData *data = [[NSData alloc] initWithBytes:sqlite3_column_blob(init_statement, 6) length:sqlite3_column_bytes(init_statement, 6)];
        if(data == nil)
            NSLog(@"No image found.");
        else
            self.pictureImage = [UIImage imageWithData:data];