I am working on an iOS app. Client side is written in Swift.
I want users to be able to store text and images in a local DB, and then transmit the DB records to a server.
I already implemented client-side data storage (but not for image files) using SQLite DB. I know that it is possible to store image files as BLOBs in SQLite, but is it wise to do so? What are your experiences? If SQLite is not the right DB for this use case, what would be better?
This StackOverflow answer discusses why saving an image in a database isn't the greatest idea.
I think the current best practice for saving images on iOS would be to save the image to documents or the photo album, and save the file path to the image in the DB. UIKit has UIImageWriteToSavedPhotosAlbum() which will save the image for you.
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I was wondering if it was possible to put pictures into DynamoDB tables from an iOS device. If so I was wondering if someone could provide me with an example using the Swift language as I have no idea where to start.
DynamoDB supports attributes of Binary type. You could have an IMAGES table where you store items with an image Binary attribute value. The maximum item size of DynamoDB items is 400KB. If the images you are trying to store are larger, or can be larger than 400KB, then you will not be able to store those images. In case you want to support images larger than 400KB, store S3 links to the images in DynamoDB, and store the actual images in S3. It might be easier to only store links to images in S3.
Yes its possible if the images are small enough - better answer: don't do it. Just because you could, doesn't mean you should.
If you are working in/on the amazon stack, s3 is a much better place to store images.
I'm starting a new project (and very new to Core Data) and was curious about how to manage images within Core Data and an Asset Library. I've done some reading and am just unclear on how everything works together.
Is it possible for each Managed Object to have an "asset library" of images? ie. can the asset library be populated with Core Data data.
What is the best way to handle having a large array of images attached to a managed object?
If anyone can point me in a direction of an article/tutorial or provide further guidance, that would be greatly appreciated.
Thanks!
Yes Core Data can handle storing an image asset database as well as the images themselves. Core Data has an option that will let it store large binary objects as files, rather than in the sqlite database itself. Core Data would be effective for storing details about the images and for categorising them into albums, projects etc.. It would also be useful for searching on these attributes.
Typically you would not attach a large array of images to a managed object. An image would be represented by a managed object and one of the attributes of the managed object would be the image (which Core Data might decide to store as a file somewhere).
I think you might be out of luck if you want to use iCloud for replicating this image library because I don't think Core Data will sync these externally stored image files.
https://developer.apple.com/library/ios/releasenotes/General/WhatsNewIniOS/Articles/iOS5.html
Managed objects support two significant new features: ordered relationships, and external storage for attribute values. If you specify that the value of a managed object attribute may be stored as an external record, Core Data heuristically decides on a per-value basis whether it should save the data directly in the database or store a URI to a separate file that it manages for you.
if you store your images in image assets and Managed Object have the "asset library" of images, then you will have the problem on updating the images.
and even if you do not want to ever update the images then why to store it in core data ?
solution is : have the images in image assets and also store the binary data of images in core data in launching the app.
by checking a date of modified coming from a web server you can check whether to update the images or not.
this link is helping you to import anything to core data easily done.
I have an iOS app that makes use of an sqlite database. I need to persist several pictures I enable the user to take and save, what should be the most appropiate way to handle that? To store them into Documents as jpeg image files? To store them into the database? I've found some posts dealing with both that options, but I'd like to know which one is the most correct or the most recommended...
Thanks in advance
You can use either approach. Like neilco, I would lean more towards storing the images as files in your documents directory and saving paths to them in your database.
You can also store them as BLOBs in your database. If you do that, make sure to make the image BLOBs separate entities, and only load them when needed. That way you don't bog down reading of your "normal" database entities with image data.
I would be inclined to store the images in Documents and create a record in the database with the path to the image.
I'm developing an app that uses core data (with UIManagedDocument) for storing user-generated data that I would like to sync with iCloud. I also would like to sync photos that the user takes with the camera within the app.
I read that it's not a good idea to store the actual photos within core data; rather it's better to store the photos in the file system and put the fileURL in core data.
Using this method, what is the recommended approach when using UIDocument to store the photos in the file system (under the Documents folder)?
I've thought about:
For each individual photo, use a NSFileWrapper(containing the
actual image and thumbnail image), or
Use a top-level NSFileWrapper, and put all NSFileWrappers in it for each photo
Similar to #2, but just put all photos/thumbnails directly in the top-level NSFileWrapper
Which approach is better for syncing photos with iCloud? and are there better approaches?
The best approach in this case is to let Core Data decide where to put it.
Open your Core Data model GUI -- click on your attribute that will hold your binary data -- look to the right -- there is a check box that indicates if Core Data should use external storage if it wants. Select it.
That's all. If Core Data needs to use external storage, it will do so -- you wil neither know nor care what it decides.
There are various ways for iPhone applications to save data (for example: NSUserDefault, XML, document, SQLite, etc.).
Our company always uses NSUserDefault to save data. However, I don't think NSUserDefault is very good because in my experience, it has been slow.
I am curious how you store data for your applications and when you recommend using each of the different methods. Please share your experiences that will help me to understand the advantages and disadvantages of these different storage types and develop a more efficient application for my users.
You can store small data in NSUserDefaults but when you have large database then you need sqlite or coredata for storing the database. use of coredatabase is good for big database this is provided by apple and it is to efficient in accessing database.
NSUserDefaults or document directory is used for small database(suppose need to store user name for single user or some other info).
You just need to know about sql queries to store data in a SQLite3 Database or You can use Core Data for back end storage. Core Data is one of the best options to use for storing data.
NSUserDefault should be used for storing small information.
You can use NSUserDefaults for storing any small data which you want to persist when your application closes. This you can use to store login details but yes if it is be secured, use keychain. You can definely use NSUserDefaults for storing setting options.
SQLite database is any easy way to store large data. Core Data is best option. but you can use SQLite if your application data is not too large.
SQlite Database can also be used to store BLOB data e.g. to store pdf file bytes downloaded from server and whenever you want to use it, just write those bytes to pdf file. This will also keep data security since BLOB data in SQLite cannot be viewed.
Its good to use coreData for large data storage in the IPhone Memory space. ITs a wrapper on top of the database which helps us to store in the form of objects.....
U can find many examples on this...