I am developing a relatively simple new free iOS app. As it's free I decided to go straight for iOS 5 as a target to allow me to try out some new features, particularly story boards.
Once I've got my head around them storyboards are wonderful, I've written hardly any boilerplate code at all up the point of a working prototype.
My model at the moment is is non persistent, after all it's just a prototype, but I've started to wonder about the best way to make it persistent. The model consists of essentially a list of custom objects which contain text, images and locations.
And so to the questions.
If I have a fully working model in memory is there a relatively simple to convert that into a persistent core data representation ?
If I want to have synchronisation to a backend web service at some point will this help ?
Should I start again with a core data application and throw away the prototype ?
All depends on your data set. If you have a large graph with relationships, Core Data might be a good idea. For simpler data sets, you could write it out to a .plist in the user's documents directory. For very small amounts of data, you could persist them into NSUserDefaults.
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when I develop an iPhone App (Time Tracker, ToDoList etc) I never know whats the best way to deal with the data. Once I used a plist, next time sqlite or CoreData.
How do you decide whats the best for your project?
(Only talking about data management)
For Example if you want to develop:
Time Tracker App > Is PList your choice?
RSS Reader App > CoreData?
Photo App > sqlite?
EMail Client > ?
For a beginner can you point me roughly to proper directions?
(I know it depends a lot on the App and what you like to do with
it but any thought will help)
I'm far away from developing complicated apps, they are still pretty simple.
Thanks for help,
Marc
You can use these rules of thumb to decide what storage model will work for your app.
If the data fits in memory entirely and is relatively unstructured, use plist
If the data fits in memory entirely and has tree-like structure, use XML
If the data does not fit in memory and has a structure of a graph, and the app does not need extraordinary query capabilities, use Core Data
If the data does not fit in memory, has a complex structure, or the app benefits from powerful query capabilities provided by relational databases, use sqlite
If the data must be secret (e.g. a password), use keychain.
Note that these choices often overlap, because multiple storage models will fit the same app. Your final decision depends on your personal preferences - you pick a technology that you understand better.
There was a very good question about sqlite vs. Core Data on Stack Overflow, you may want to read through the answers to that question.
My rule of thumb for each of those would be:
Time Tracker App > Core Data
RSS Reader App > Core Data
Photo App > Core Data
EMail Client > Core Data
Though in each case there would be things you would store on the file system. For instance, the photo app would obviously put the actual photos on the file system. The text of the emails would be on the file system etc. The actual RSS messages might be text files too, but with meta data in Core Data objects.
At some point, you might find that the data you are storing is outgrowing the scalability of Core Data. At that point you would consider moving to SQLite.
The point is that Core Data is so easy to use and so superior to the alleged lighter weight alternatives, why wouldn't you use it?
Creating a budget app (not for release, just something quick & dirty) and I noticed upon starting the Master-Detail template that Apple uses Core Data and NSFetch results to populate the tables (think Notes on an iPad).
My inexperienced and unprofessional programming instincts wouldn't think twice about grabbing an NSMutableArray, taking the names of the table cells and cramming them into an index, saving that as an NSUserDefault and then upon reloading the app, populate each cell at it's current index with the same index in the NSMutableArray so the contents is back where the user left it. Just wondering, how inefficient is this compared to using Core Data?
On a side note, any easy way of communicating between two different tables that both hold dynamic data?
Up to a few hundred records, don't worry about it. It would be indeed wonderfully "quick and dirty".
Still, the learning curve for Core Data is not as steep as you might expect. Once you get the hang of it - and your simple app is great way to explore that API - you will find that you want to do everything with it. Even large projects will seem easy.
Your choice.
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 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.
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.