I am making a simple iPhone app that will basically be an editor.
As such, I need some way to store the documents the user creates.
Since on iPhone, the concept of the filesystem is not present for the user, I searched around to see what I should use.
I found this question & answer that basically says to use Core Data, but I recently found out about NSFileManager.
My question simply is, for user-created documents, what is the best storage system to use? Traditional files by using NSFileManager? Core Data? Something else?
Personally, I would use CoreData because it will abstract away all of the file-management code for you. If you are making simple text documents then this isn't such a big deal, but if you are working with a complex document architecture (i.e., a collection a numerous objects) then it can save you a lot of effort.
If the user wants to export their document it is very easy to write a function to do so with your CoreData objects.
The only downside to CoreData is that if you are using non-standard attributes it can get a little bit tricky, but it is certainly not a deal breaker in most cases.
People create document formats without CoreData all of the time, so there are plenty of examples out there, and it will just come down to personal preference. There really isn't any generalized right answer to this - it a design decision that should be evaluated on a per-app basis.
If all of your data for displaying the file is contained in one long string (like HTML) then I would recommend that you use the file manager, since it will be easy to get a list of files in a certain directory to display to the user for opening. However, if they are not self contained (like NSAttributedString, which has many stored formatting regions along with the actual content) then you should use CoreData, as it will be easier to keep all the pieces together.
Related
I'm working on an iOS app that will need to save data onto files. I chose to go for a Document Based app, precisely an app based on a UIDocumentBrowserViewController so that I can easily save and load files from the system's Files app.
Since the data I need to save/load on a file is quite complex: big hierarchy of different objects, with meta-data, image files, etc. I'm wondering what is the best technology to use going forward.
I came across NSFileWrapperand its ability to save different files as one. And I could definitely use that. But I also saw UIManagedDocument and the ability to use Core Data in my project while maybe saving the content of the Core Data database (I know it's not quite a database, but you know what I mean) into a file that I could write somewhere in the File App.
Is this a behavior I can expect?
To reformulate: I'm wondering if I can read/write files through a UIDocumentBrowserViewController, with data described by a UIManagedDocument that works with Core Data.
Thank you in advance. 🙂
As you have discovered, UIManagedDocument is there for your kind of application. And it does feature methods to write and read additional content like the metadata or image files you have, within the document package.
That being said, I have never used UIManagedDocument, and have never seen it used by others. A quick search of GitHub finds only this one project with two contributors who wrote a wrapper around it in 2013. Also, there does not seem to be any sample code from Apple, and the remark in the the writeAdditionalContent(_:to:originalContentsURL:) documentation that Additional content is not supported on iCloud leaves me a little concerned, but maybe it's a good sign that the Core Data team knows where to draw the line.
I have used the macOS counterpart of UIManagedDocument, NSPersistentDocument. It is in a similar situation of not being used very much, but with many more known technical issues. So a few years ago I switched to BSManagedDocument, which purportedly mimics UIManagedDocument to support Core Data in all its modern glory. I have been happy with BSManagedDocument.
In summary, if I was in your situation, yes I would give UIManagedDocument a try. But don't be surprised if you need to use a DTS support incident or two during your development.
What is a good way to store many key/value pair entries in a mobile (iOS) application, such that they can be easily exported/imported?
I have considered a single large JSON file - would this be too slow/large with 200,000+ entries?
I have also considered CoreData - but could the data be moved easily via, for example, email?
Think of an address book. Contacts can be easily imported/exported, what data storage model would be comparable?
Thank you.
EDIT: Examples
Notes - be able to select and view short notes in a table. Each note is < 100 characters.
Saved bookmarks - each bookmark is stored in a table.
I have considered a single large JSON file - would this be too
slow/large with 200,000+ entries?
I don't know. I can make a guess. The guess would be yes, it's both too large and too slow. However, you can always test it to find out.
I have also considered CoreData - but could the data be moved easily
via, for example, email?
That depends on how you want to share the data. You call email easy?
Core Data is a framework. You can use any type of backend you want (you can even write your own). The most common is probably SQLite.
If you use Core Data, you can keep the data files in a separate subdirectory and copy them just like any other file.
However, if you want to share data via an online service, you may want the ability to import/export JSON files.
If you are talking about synchronization, then that's a different beast entirely.
Basically, there is no single right answer. You have to assess your requirements, and then determine which solution meets your needs.
On the surface, it seems like using Core Data would be a good fit, but it depends on how you want to use the data in your application. Only you know that answer.
I'm looking into using UIDocument en NSFileWrapper to store 'projects' that contain quite a few large video files and some small text files. There are a few problems that I run into, and I'm starting to wonder if UIDocument is still the right strategy.
Performance
As far as I can tell, NSFileWrapper loads everything in memory. This can be a problem when working with large video files. I think it's possible to work around this by using custom save and load methods that forego the standard NSFileWrapper.
Metadata
I want to display a list of all the documents along with some metadata. This can for example include a preview image, number of recorded scenes, length of videos etc. The only way to fetch this data now is to open each document and retrieve it. Probably quite slow, especially with large documents.
Solutions?
I see two solutions now: ditch UIDocument altogether and go for a custom architecture, or use some kind of centralized metadata file. Drawbacks of the latter is that I have to manage metadata in two separate places and that I need to keep them in sync manually.
Is UIDocument still the way to go here, and if so: What could be a way to solve these problems?
Based on the comments the asker found a way to move forward as such:
drop UIDocument in favor of a Core Data solution. I now save all my
data using Core Data and manually manage the large files on the
filesystem. It works pretty well for me, and I'm glad I made the
switch. The only thing I had to give up was easy iCloud syncing. But
with files as large as these, that wasn't really feasible anyway. It
seems you can create your own file wrapper class to work around some
performance problems with large files.
I have been tasked with creating an iPhone application for a client.
I have some coding experience but only in C# so it doesn't really help here but other than that I am a complete novice on iPhone coding.
What I am trying to accomplish is to get some form of store locator on a map.
I have successfully added the map, get the user location with it zooming into the user. I have added 2 annotations (Which I believe the the best way to go about showing locations on the map).
I have 2 queries that I need help with, What is the best way to go about listing the stores in some form of database. XML, PList, .sql etc... (this would also need to be read from the web as it would need to be easily edited as new stores would be added a lot). Is it possible to loop through the database and dynamically add the stores onto the map within a location of the user?
I am not asking anyone to write any code for me, I am just asking for some help as I have googled the hell out of this and cant seem to find anything that helps.
Any help would be much appreciated,
Thanks
In terms of your potential formats for saving these locations, you options include:
XML/JSON are good formats for exchanging data with a remote server, but less ideal for a local database (though they theoretically could be used for that purpose). JSON is marginally easier to deal with (using NSJSONSerialization), but XML can be relatively easily parsed, too (using, for example, NSXMLParser). If you're doing network operations, I also heartily recommend looking at AFNetworking, which offers some nice advantages over the standard NSURLConnection. This, of course, presumes that you have written a web service on your server to deliver the necessary JSON or XML feed.
Plist is a fine, simple format if you want to save a short, local list of locations on iOS devices. Saving data to a plist is as simple as calling writeToFile method for your NSDictionary or NSArray and reading data is done via [NSDictionary dictionaryWithContentsOfFile:filename] or [NSArray arrayWithContentsOfFile:filename].
Core Data is a good, iOS-specific format for larger databases. It's probably the preferred iOS mechanism for dealing with persistent objects, but is an order of magnitude more complicated than plists.
SQLite is also a good database format if you're thinking about a structure that lends itself towards larger database, but also which lends itself towards eventual rollout to multiple platforms (e.g. both Android and iOS). If you decide to go SQLite route, consider an Objective-C wrapper (such as FMDB), which will simplify your life greatly.
Implicit in all of the above discussion is that, yes, you certainly can write code that iterates through your database and/or model data structures, extracting the necessary location information, and dynamically add annotations to your map. The Location Awareness Programming Guide should help introduce you to some of the MapKit related features.
"Is it possible to loop through the database and dynamically add the stores onto the map within a location of the user?"
Yes. Just as you have created those first two annotations, you now need to create more annotations in a loop. The only additional info you might need is that once you have added an annotation to the map it will stay there until you remove it. So you don't need to maintain your own list of annotations unless you want to do something else with it. Just fire and forget. So now your question comes down to how to loop through data from your chosen data source in Objective-C and not MapKit specific.
I know this is old but if anyone else comes across this like I did, you can use tmysqlkit by tanmay bakshi to read and write directly to a mysql database on a server.
Best,
Sam
I am writing an iPad app that will be expandable with new items via in-app purchasing. For example, my current plan is to have a jpg pattern and a matching plist file with the parameters I need to expand that pattern into a full picture.
The user will select one jpg/png from a list of small thumbnails - the list is held in Core Data - and the app will find the matching plist for displaying the jpg/png correctly. I'll only have about 10 of these open at one time. But I could end up with storing 1000s of jpgs and plists.
Does storage of lots of small files cause app problems?
I'm going the plist way, rather than storing the parameters in Core Data, so that if I need to add parameters later, I don't have to migrate the database, just change the access in code. (And when I'm creating the patterns, it's easier to concentrate on a plist file rather than a Core Data row.)
The app seems to work really well at the moment, but I'm worried about futures...
My app does also use Core Data for other things, so I could change over if the app will get bogged down with number of files.
Thanks.
Saving a large number of small files is not a problem as long as you have a well thought out means of naming and tracking the files.
Remember that the user does not have the same flexibility and ease of file management on a mobile as they do on non-mobile platforms. Designs that work on non-mobiles are unworkable on a device used on the move with one finger.
However, when you say:
And when I'm creating the patterns,
it's easier to concentrate on a plist
file rather than a Core Data row.
... the use of "row" suggest that you haven't fully grasped Core Data's utility. Core Data doesn't use rows, columns, tables or joins. It's an object graph management system that sometimes uses SQL way behind the scenes.
Core Data is designed to handle data in a way that meshes seamlessly with the rest of the object oriented API for the UI and other services. When you use other data management systems like plist, you will most likely end up manually duplicating a lot of Core Data's functionality anyway.