I am creating an epub3 with a form inside. Is it possible to save the information that was inputted in the form locally when the user is offline and send it to a web service if the user is online?
THIS is a good question! Finally...
OK, for the first part of your question (saving the information) you can use localstorage, for some great info on that go here: http://diveintohtml5.info/storage.html.
The next part of the answer is not quite so simple: ideally you could just use some sort of try catch with an XHR request, but chances are that won't work because most ePub3 readers (actually, pretty much all of them except Readium) don't support XHR or external request functionality. See this post for more info on that: http://beneaththeink.com/blog/who-supports-epub/.
If you want your book to be distributed through any of the "normal" channels (pretty much just iBooks since you need Script support at this point) you won't be able to send the data at this point in time...
However, if you will be distributing the book yourself for use on Readium and iBooks (or if you want to plan ahead and hope for support) there are a few hacks you can do. My personal favorite, is embedding the data in a media request (IE www.yoursite.com/fake.m4v?data1=localStorage.data1&data2=localStorage.data2) and pulling out the data on your server. This would be nested in a try catch and activated whenever the book is opened.
If you include the base url (www.yoursite.com) in the .opf file, as well as at some point in the chapter which contains the script, this will work in iBooks! If you don't include it in the .opf the request will get blocked right out of the gate... For more information on why this won't work in the actual iBookstore check out this post: http://beneaththeink.com/blog/external-video-in-ibooks-epub-files/.
Best of luck!!!
I have an app that basically has news and updates about a certain subject. How do I get it to work that when I update something let's say in my website it would also update what's on the app. Do I usee RSS for this?
You need some web service to deliver the data. In terms of what format a web service can use, there are a variety, but two prevalent formats are XML and JSON. RSS is, essentially, a particular form of XML.
On the iOS side, you can parse XML using NSXMLParser (see NSXML Parser Class Reference). If you're parsing JSON, you can use NSJSONSerialization (see NSJSONSerialization Class Referece). For both of these, you can google the class keyword followed by "example" or "demonstration" (e.g., "NSXMLParser example" or "NSJSONSerialization demonstration") and you'll see tons of examples. If you have an RSS feed, you can google something like "iOS RSS example".
It may be dictated by what you can easily render from your server, XML (or, in particular, RSS) or JSON. For example, if you're using some content management system on your web site, it might offer RSS feeds, or something like that. In the absence of that, you may have to write your own server interface to retrieve the data in XML (or RSS) or JSON formats.
In addition to #Rob answer I would point couple mode things:
You can simply prepare databases with your information (like SQLite) and just download them from your web site to your application.
You need to have some way of notifying application about new content and for that you might want to use remote notifications. http://developer.apple.com/library/mac/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/IPhoneOSClientImp/IPhoneOSClientImp.html - this way you can send notify messages to your app, and user will know that there is something new to download and read.
I have created a few small apps for the iPhone so I have some experience. An organization that I'm in asked me if I could program a weekly newsletter app for them. I though it would be a good challenge so I agreed. My question is: how do I get the app to update weekly without the users having to re-download or manually update? Do I connect to a database or a website? Can anyone send me the link to a good tutorial? I wasn't able to find one.
Thank you!
Your question is very general but I could give you some suggestions.
First, you need to connect to a service that provides you news info. This is needed. The service could send you an xml that you can parse and display, for example in a UITableView. XML is not the only solution. You could use also JSON.
For parsing XML I suggest you to read GDataXML, while for JSON JSONKit framework. But there are also other valid framework out there.
Then, to save data it depends on what kind of data you deal with. Here you could find different ways to save your news. Save an XML that contains your news, serialize data and save them in the local filesystem or use Core-Data.
To update your news without user actions, you have to save the last time when the app has downloaded news (for example in NSUserDefaults) and each time time the application is "activated" check for that date and update news if necessary.
Out there there are plenty of tutorials on how to (in parenthesis I inserted classes or framework that you could have a look):
consuming web service on iPhone (ASIHttpRequest - no more supported, NSURLConnection class, AFNetworking)
dealing with XML file/data and theirs parsing (GDataXML, touchXML, etc.)
dealing with JSON messages (JSONKit, etc.)
managing documents (NSFileManager class)
using Core-Data
using Property-List and/or NSUserDefaults
First three cover the first step (download). Other three cover the second one (save). Obviously you have not to use all of them. For example a configuration could be:
NSURLConnection for service, GDataXML for parsing XML data and Property-List for save data.
Hope it helps.
A simpler approach would be to make it a pure web app and update the website weekly.
Your content providers are going to have to do those updates anyway.
Check: Adding Newsstand Support to Your App or Tutorial: How To Make Your App Work With The Newsstand
In my application i need to create and save data into an xml file on my webspace and then i want to parse that xml into my iphone app. The question here is this is being done by two different parties a sender and a receiver.
But i don;t know how to parse that xml file into my app when i don't have the excat url of that xml because there will be number of people who will be using this app so how i can allocate the xml a specific url and pass that url at receiver end.
Thanks,
As there is a lot to this question I can only give you a vague answer to keep it short. The type of communication I recommend using is NSURLConnection. That will allow you to get the contents of say an xml from a URL.
As far as identifying individual users there is a few ways all of them a fair bit of work. You could create a sign in where the user has a unique username or email. Store that in the database on your server and pass it as part of the url.
You could also sort of use push notification registration where your server is required to keep an iPhone unique identifier to push information to Apple. I don't know enough to push notification to give you much guidance in this but if you don't want the user to create an account I think this would be the way. You could also query the server for a unique ID and store it in NSUserDefaults.
I would recommend the user account creation though. Also have a look at NSXMLParser for your xml parsing.
Beyond this help ask a more specific question. There are also many other ways to do this, its just the way I do it.
I can help you with the parsing of the XML.
iOS (like mac) has a built in XML parser.
Still I would recommend you use an external library, there are several available out there.
In a recent project, I very successfully used TouchXML: http://github.com/schwa/TouchXML
Here is a very simple tutorial on how to use the TouchXML library to parse XML files:
http://foobarpig.com/iphone/parsing-xml-element-attributes-with-touchxml.html
I'm planning my first iPhone app and I'd like to get some inputs as to how to build it, right from the start. The iPhone app is being built to be paired with a public facing web application that is already built in PHP.
I'd like the web platform to be central (data is housed in a mySQL database), and have the
iPhone clients talk to it and use REST'ful methods to perform the functions of the site
(fetching latest content, posting content, voting, account management as examples).
I'd like the clients to get a local copy of the data in a SQLite database, but refresh to get the latest version of the feed (similar to the Twitter app).
Couple of thoughts I have right now:
Use something like ASIHTTPRequest to send/recieve data to PHP files on the server listening for requests
JSON - would I be better off to send the GET/POSTS to a PHP that returns JSON objects, and work with some sort of wrapper that manages the data and communicates changes to the local SQLite database?
Am I totally off in how I should be building this thing to communicate with the web? Is
there a best practice for this?
I'd really appreciate any input on how you would architect this sort of a setup.
Thank you,
EDIT: After reading my own post again, I know it sounds like a Twitter client, but it is NOT, although it has similar features/structure of a Twitter type setup. Thanks!
As you already outlined in your plan, XML and REST are a great way to communicate with a web application. I want to suggest few details about how to actually design and build it, or what you should keep in mind.
First of all, I believe it's important to stick with MVC. I've seen people creating HTTP connections in view-controllers, controllers being NSXMLParser's delegate, controllers containing data in member variables. I've even seen UITableCells establishing HTTP connections. Don't do it!
Your model and its basic manipulation code should be as much extracted from user interface as possible. As you already have created the model in your web-application, try to recreate the entities in your iPhone project. Don't be afraid of having some simple methods in entity classes, but do not make them use external resources, especially tcp connections. As an example of methods in entity class you might have methods that formats data in specific ways (dates as an example, or returning fullname as concatenation of firstname and surname), or you can even have a method like - (void)update that would act as a wrapper to call class responsible to update the model.
Create another class for updating the model - fetching the XMLs from web-app. Do not even consider using synchronous connections, not even from a dedicated thread. Asynchronous connections with delegate is the way to go. Sometimes multiple requests need to be made to get all required data. You might want to create some kind of state-machine to keep the information about in which stage of downloading you are, and progress from stage to stage, skipping to the end if error occurs, re-executing from failed stage after some moments.
Download data somewhere temporarily, and first when you have it all, make a switch and update user interface. This helps responsiveness during launching the app - user gets to work immediately with data stored locally, while the update mechanism is downloading the new data.
If you need to download lots of files, try to download them simultaneously, if dependencies between files allow for that. This involves creating a connection per request, probably delegate instance for each of them. You can of course have only one delegate instance for all of those connections, but it gets a bit more complex to track the data. Downloading simultaneously might decrease latency considerably, making the mechanism much faster for the user.
To save the time and bandwidth, consider using HTTP's If-Modified-Since and/or ETag headers. Remember the time or tag when you requested the data the last time, and next time send it in HTTP's header. Your web-application should return HTTP code 304 if content has not been changed. iPhone app should react on this code accordingly in connection:didReceiveResponse:.
Create a dedicated class to parse the XML and update the model. You can use NSXMLParser, but if your files are not huge I strongly recommend TouchXML, it's such a pleasure to work with XML as document (it also supports XPath), instead of an event based API. You can use this parser also when files are downloaded to check their validity - re-download if parsing fails. That's when dedicated class for parsing comes handy.
If your dataset is not huge, if you do not need to persist downloaded data on iPhone forever, you probably don't need to store them in SQLite database, you can simply store them in XML format - just a simple caching. That at least might be the way for a twitter app. It gets easier that way, but for bigger data sets XML consumes lots of memory and processing power - in that case SQLite is better.
I'd suggest using Core Data, but you mention this is your first iPhone app, so I suggest you don't use it. Yet.
Do not forget about multitasking - your app can go to sleep in the middle of download, you need to cancel connections, and cleanup your update mechanisms. On app's wake-up you might want to resume the update.
Regarding the view part of the application - use Interface Builder. It might be painful in the beginning, but it pays off in the long run.
View controllers are the glue between model and views. Do not store data in there. Think twice about what to implement where, and who should call it.
This is not related to architecture of the app, but I want to remind that Objective-C is very expressive language. Code should read much like a sentence. Extend classes with protocols. As an example the other day I needed first line of a string. Sure, you can write a one-liner where you find first occurrence of a new-line, and get a substring from beginning till there. But it doesn't look right. I've added - (NSString*)firstLine into my NSString's protocol. Code looks so much better this way, it doesn't need any comments.
There are lots of things to consider in both architecture and design of any project, they both should go hand in hand. If one is causing trouble to the other, you need to adapt. Nothing is written in stone.
I'm currently working on an app that sounds similar to yours. I'd also suggest ASIHTTPRequest, and probably something like TouchJSON for JSON parsing, or extending/making a delegate of NSXMLParser if you want to parse XML.
As suggested by JosephH, depending on how your app works you may want to consider alternate authentication methods: I'd take a look at something token-based like OAuth, which has ready-made libraries for people to dig in to.
SQLite is totally viable for feed caching, although I prefer NSCoding so that you can freeze-dry your custom data structures.
As a general suggestion, make sure to spend a lot of time thinking about every use case and corner case for connections: it's easy to assume a user will only contact the server in certain ways and at certain times, and then after you throw in multitasking/incoming calls/lock screen/memory warnings, things can get hairy without any planning.
All in all, you seem to be on the right track, just make sure you plan out everything beforehand :)
Apple have a brand new in depth piece of sample code - MVCNetworking that shows in depth how to use subclasses of NSHTTPRequests and NSOperationQueues.
As others mentioned, I think you are asking the right questions and are heading in the right direction. All of the replies above are valuable advice. Here is my advice, and I hope you'll find it useful.
No matter which method/library you choose to talk to your web services, I think it's important to make a clean separation in the way you design your data model on the phone VS. the data model in your web application. You have 3 major distinctions to keep in mind for your design:
Data model on the web application (reflected by your existing mySQL database)
Since this is already there, there is not much to say about it, except that it will influence a lot your design for the following 2 parts. I suggest to make this model the 'master reference' for how your data is represented across platforms.
Data model on the iPhone app (reflected by the information you need to display in the iPhone app)
This is where the fun begins. First, you need a good understanding of what data you need to display in the phone app. So have a good, high level design of your app first (use pen and paper, draw mock-ups of each view and the interactions between them, model the navigation between your view controllers etc.). It really helps to understand the interactions between your view controllers and the various bits and pieces of data you want to show in the app. This will help you create the requirements for the data model on the phone. Based on these requirements, map the existing (web) data model to a new model, suited to your iPhone app. This new model may or may not include all tables and fields found in your web app. But the general representation of the 2 models should be very similar (e.g. relationships, data types, etc.)
Data model used to communicate between the 2 above (this is your 'data exchange protocol')
Once you have the 2 representations of your data above, you need to 'translate' from one to the other, both ways. Design your data exchange protocol to be as simple and compact as possible. You don't want to waste bytes on useless information, as transmissions over the network are costly. (As a side note, you might think of compressing the transmitted data later on, but it's just as important to have a good design from the beginning). It's probably best to begin with a protocol in which the metadata is the same as the one in your web application model (e.g. same relationships, names of tables, attributes, etc.). But remember, you'll only have to serialize/de-serialize those entities and relationships that you listed in point 2) above. So design accordingly. Your exchange protocol may also include session tokens, authentication info, a version number, or other metadata, if you need it.
Remember: your data exchange protocol is what will de-couple your web application and iPhone application models. I found that it's best to de-couple them because they may both evolve over time. The data model on the iPhone for example, may evolve a lot especially when you will find that you need to re-model some relationships or add/remove attributes from your entities in order to improve application responsiveness, or the user experience, the navigation, or whatever.
Since this is a whole concern in and by itself, well, you need to design a generic serialization/de-serialization mechanism on top of your (JSON/XML/whatever parser you choose) that is flexible enough to sustain the potential differences between your 2 data models. These differences might be: entity/attribute/relationship names, primary key identifier names, data types, attributes to ignore, and the list goes on. I would definitely implement a serializer/de-serializer utility class in the iPhone app, backed by a .plist configuration file containing all supported entities, concerns, aliases you might have. Of course, each model object should 'know' how to serialize, de-serialize itself and its relationships (i.e. the required object graph depth).
One last note, since you will end up with 2 representations of your data, you will need a way to uniquely identify an object on both sides. So for example, think of adding a uuid attribute to all data that needs to be exchanged, or use any other approach that suits your needs.
I am building an app that has similar requirements to yours, and these are the approaches I found to be best so far. Also, you might find this video useful (it inspired me a lot on how to implement some of the issues I mentioned above and is especially interesting if you're using CoreData) :
http://itunes.apple.com/ca/podcast/linkedin-important-life-lessons/id384233225?i=85092597
(see the lecture entitled "LinkedIn: Important Life Lessons on CoreData & GameKit (March 12, 2010)" )
Good luck!
It's quite a broad question, and I think you're going in the right way anyway, however I'll do my best to give some advice:
JSON, ASIHTTPRequest and POSTs to PHP scripts sound like a great way to go.
If the data is not really sensitive, I'd use http most of the time, and use https only for a login page that either sets a cookie or returns a "token" that you use in subsequent requests. (HTTPS can be quite slow over a 3G connection as the overhead in terms of number of packets to setup an SSL connection is higher than a plain TCP connection.)
You should make sure you correctly pass any data from the input to the PHP scripts to the database, to avoid any SQL injection attacks - ie. used parameterised SQL, don't create sql queries by doing "SELECT * from users where username="+$_GET['username']"
I would do this like I have done with a lot of AJAX web-page stuff. i.e.:
Have a URL on your server side package the information to be transmitted into XML format. (This can be through a CGI/PHP script or whatever). Your transmitting XML in the message body - so it's easy to human read and debug with a standard web browser.
Use the standard iPhone NSXMLParser methods to parse out the individual data fields from the XML doc, and write it back to your database. This method is equiped to both fetch the data from a URL and parse it in one call - like:
NSURL *xmlURL = [NSURL URLWithString:#"http://www.example.com/livefeed.cgi"];
NSXMLParser *myParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];
Walk through the data hierarchy with the NSXMLParser methods and populate your database accordingly.