We have a requirement to be able to store the data on device and make it available even when device is off network, and when device comes back to network it should be able to sync the stored data and be able to update the stored data with latest server data and so on. I understand that lots of this needs to be implemented using sync/notification/versioning stuff ourself.
However are there any recommended framework/API (other than vanilla Core Data) that people use to store large amount of data to be stored/cached on iOS devices? Any reliable and intelligent caching solution out there?
Any recommendation of this sort will be very helpful.
Related
I'm currently finishing up a project for IOS in Swift in which I've used an SQLite database to store data with SQLite.swift.
At the time of coding I didn't know that SQLite files are stored locally on the device/simulator and I need a way to run the app and have the database synced between two devices, as soon as possible. I tried swapping over to Firebase since I heard that would be a solution but I'm not at all familiar with it and am worried it might be risky given all my functions are written for SQL tables. I also thought of keeping the SQL and adding on a firebase database to fetch the data from but I'm not sure how to execute that.
The solution doesn't have to be 100% reliable for all cases- I just need to simulate running the app on more than one device with synchronised data.
Does anyone have any suggestion for a way to do this? Or a way to store the data on a computer so that it can be accessed by both devices?
Any advice is appreciated!
There are no elegant solution with pure SQLite database. Just few offers:
Moving to CoreData (You will get all what you want with sharing data between devices)
Uploading database file to iCloud from one device and download it from another device
Build up classic client-server communication
Let iOS do the synchronisation via iCloud, e.g. use Core Data with CloudKit: https://developer.apple.com/documentation/coredata/mirroring_a_core_data_store_with_cloudkit/setting_up_core_data_with_cloudkit?changes=_1
I want to write an app for both iOS and OS X which shares a common database and syncs via iCloud. I had planned to use Realm, but then wondered if it is a good fit when used in conjunction with CloudKit or should I use Core Data instead?
Thanks.
iCloud allows you to backup and sync files across all connected user devices. With Realm, you could theoretically settle on that as long as only one single client access the data to any point in time, which will be hard to guarantee. Furthermore there are restrictions on the file size, which will make this solution likely fragile.
CloudKit is a backend-as-a-service solution, which allows you to setup a schema and request your data from there. It doesn't bring a builtin persistence layer. You would need to provide that logic yourself, for integration with CoreData as for Realm.
I have an iOS app that uses Core Data and ParcelKit to sync with Dropbox. However, the Dropbox Datastore API only allows records of 100K so it will not sync images that I store in the database. Any other workaround than storing images as separate files with filenames stored in the base? It is a little fragile when user can alter the content of the imagefile-folder thus braking the link to the database.
You should not store large images in the Core Data persistent store. Apple recommends that you should only store small images, such as thumbnails, perhaps 20K max. If you go beyond that, performance will eventually degrade significantly.
Thus, you cannot really avoid storing the images in separate files and storing their name/location in Core Data. This is the recommended pattern.
I do not see why you think this is fragile. Presumably you will store the images in the app sandbox there is no way the user can fiddle with them unless the iPhone is jailbroken.
The Dropbox sync should be managed independently from this setup.
FYI Dropbox just killed the Datastore API and will take it off line in 2016. :-(
You should monitor this ParcelKit Issue:
Dropbox Datastore is Deprecated #34
https://github.com/overcommitted/ParcelKit/issues/34
I've already managed to program a webapp for personal use I'm really satisfied with. Not being something meant for public usage and distribution, I didn't want to go through the hassle of jailbreaking my device just to be able to run my own application, so I made this seamlessy looking and behaving webapp (and of course I've added it to the other apps saving it as a "Home application")
Since the start time can be a bit slow and I'm constantly pushing my data from and to a remote server, can I force the usage of html5 offline browsing (with a cache manifest) even when I am online? Also, I'm thinking of persisting the data as local storage and from time to time synch it to the server. Since I've never used html5 local storage, how much reliable is it? Can I lose my data?
Is this a viable pattern to quickly create a personal iPhone app? Thanks
Yes, you can force the usage.
so basically you should a very simple checking :
if(localStorage["mycontent"]!==null)
{
// do it offline.
}else
{
// retrieve from server database
}
For your question regarding :
Also, I'm thinking of persisting the data as local storage and from
time to time synch it to the server. Since I've never used html5 local
storage, how much reliable is it? Can I lose my data?
The answer is it depends. If the data is static (or can only be changed by you and not other user ) it's reliable. You also have to take note when a data can be considered expired so localstorage can be filled with refreshed data from the server.
But take note that cleaning history is also remove your data, so only use Localstorage as a cache/mirror of the data in the server.
window.localStorage.setItem('x',y);
window.localStorage.getItem('x';
window.localStorage.removeItem('x');
Lets you store, read and delete persistent data in HTML5. See https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API
But note that on IOS Safari puts this data in the cache folder which on occasions gets expunged. So do plan a server sync and restore of this data if important.
Alternatively use a local SQLite database for a more persistent persistence....
My client states in an iPad app brief that the data (i.e. products and images) must be taken from an online source and saved. However, the app must also have an offline mode which shows this same data from when the app was previously online for times when internet access is not available (kind of like an offline reader). What would be the best way to tackle this? Any help greatly appreciated.
Download the data when the device is online and store it locally using whatever mechanism seems most appropriate (SQLite, Core Data, property lists, your own file format, etc.). Use this cached data when offline, and when online too unless it has changed. Create some mechanism that you can use to detect and download updates (preferably just the changes) when online.
This will be a big help for your users not just when they're offline, but online too. 3G data plans for the iPad are usually limited, so the better you can avoid repeat downloads of large resources like images, the better for your users.