Can anyone tell me How does the Sync Button on many Iphone app. works (like 'Le Monde').
The button download and replace all files of the application? only look for change (new entry) on the database and add them?....
Thanks,
Typically a button like that is making a web service call, depending on the call you may be updating or replacing the information currently on the device.
Some web services will allow you to ask for information since a certain date:
/FetchArticles?afterDate=200911011952
Some will just provide you with a set amount of information.
Most of the time the calls to a web service will return light enough data that you can just replace what you had with what you fetch, but sometimes the data is a little heavier(images, video, etc...), so you'll want to hang onto what you already have and add to it.
Without knowing more about your App, or if it even uses network resources it's hard to provide any more help.
Related
I have an application in the store that has a bunch of UITableViews, each has a bunch of items that when selected, load a UIWebView that loads a local HTML file. The reason I do this is so it allows for viewing when there is no internet access, however it makes it tedious to update.
How would I go about both keeping local files, and keeping web files, so that If I update one on the web it would let the user know there is an 'update' and it can download and overwrite the old file with the new. Is this possible? Like I would make myself a backend to edit my HTML, and have a connection to the app so whenever I clicked save the app would know to ask the user to update the files so I don't have to submit to apple for such small updates.
But I still need to allow offline viewing in case they didn't have internet access.
What technologies or techniques would I have to research to accomplish this?
Thanks
what you're looking for is an html5 concept called application cache.. it directly addresses your problem. With app cache you can cache static content at the client side, which they can view even if they're offline, yet they can update it when the content on the server changes. If you look around you'll see people use this for the iPhone as well.
update:
What way would I go about rewriting files on the phone from ones on a server?
you basically update the cache to do that. from the docs:
The application cache automatically updates only if the manifest file
changes. It does not automatically update if resources listed in the
manifest file change. The manifest file is considered unchanged if it
is byte-for-byte the same; therefore, changing the modification date
of a manifest file also does not trigger an update. If this is not
sufficient for your application, you can update the application cache
explicitly using JavaScript.
I encourage you to do some reading on html5 local storage just to get the concept of local cache and manifest files etc, then just follow through the instructions on the apple docs.. It's not that difficult.
You can cache the content as abbood said but that won't allow you to provide initial offline content.
Another approach would be to use NSURLProtocol, which allows you to swizzle a request. For example, if you have a request for "http://google.com", you would be able to either change the URL or load your own content (say from a local directory).
I am currently developing an app for a company that is in a very competitive field. I have finished all of the features of the app that they requested except for one, making it somehow protected from their competing companies to download and use. I thought that I could set up a UIViewController with a password field that would check against some kind of database, but I'm not sure how to do the checking against a database part nor the practicality of it, and was hoping I could get some ideas on how to do this so that other companies couldn't steal and use this app without a password or something that changes like every 30 days or something and is kind of like an activation code.
Review the WWDC 2012 video "Building and Distributing Custom B2B Apps for iOS". I'm unsure if your app is in this B2B classification, it seems that it might be from your description.
What I ended up doing (if everyone needs a reference) was setting up a server with an SQL table that has pass codes in it. Since apple does not allow for any sort of system that requires you to "buy the app from outside the app store" I made a dumby username field (shame on me) that takes any value you like and then requires to have a pass code that fits. Once the pass code gets authenticated with the web server in a json sql request (there are plenty of api's to do this with) it comes back and sends the user to the first screen and sets a value in a plist with how many days of use the user has left. Whenever the user opens up the app it checks to see if the date is different from the last date logged in (saved in the same plist file) and if it is different then it calculates the difference and deducts that many. When the count reaches 0 it sends the user to the pass code authentication screen again. A bit complicated but an effective method of getting around Apple's restriction on not having a sort of pass code system like this. Thanks for the answers, unfortunately enterprise did not work for this company since they needed to be able to distribute the app to as many 3rd party members as they wanted to without having to worry about them leaving the company for other suppliers and remote management of the app (I.e ability to remote uninstall) was also not an option. Hope this helps someone someday!
Say I have a TODO list iphone app, that can be edited/viewed from both a web application and the iphone application.
When on the iphone, when a user views all his todo lists, or sub-items, I would think that each time the user views a particular list it shouldn't be hitting the web applications API every-time, but rather cache locally the values and only hit the web when things change.
What strategies are there for this type of scenerio?
I agree with you in your dirty-otherwise-do-not-contact-the-server point. And I think this point is pretty straightforward and easy to implement.
However, be careful in this scenario: it gets dirty but at the same time, the device cannot reach the internet. In this scenario, I suggest you check the internet accessibility on a frequent basis (even when your app is in the background), and try to reach your server and update whenever possible.
This is a tricky problem. I'm currently working on an app that needs to perform a similar synchronization, and I haven't decided how I want to handle it yet.
You're right in that you don't want to be hitting the web repeatedly. It would slow the app down considerably. Keeping a local cache is the way to go.
One drawback is that the user could change/add an item on the web and you wouldn't see it on the phone. You'd need to have a refresh button (like in the Mail application, for example) to allow the user to get the changes.
Then you have an issue with conflict resolution. Say the same item is edited on both the phone and on the web. How does the user pick which one to keep, or do they get duplicated?
I think the best way to do this is to replicated your server's schema in CoreData. Then load a given element from the local DB, and in the background go out and check that element for updates if the device has an internet connection. You're hitting the db each time, but the user is not slowed down by the process.
You should not query the internet everytime you view the list.
But when you make updates to it, or edit it, you should update the server as well. That will make your life a whole lot simpler. That way when the user updates an item that he deleted in the web server, the server will just throw that request out...
Okay, I want to have an app that takes phone numbers from an online database and displays them in a table view. When the user is not online, I want them to still be able to see the numbers they already got from the database in the table view. If the user manages to go back online, the database updates the view. My question is, is this possible to do and if so, what's the best way to approach it? (bit of a newbie, please help me out)
There are many ways to do what you are asking, depending on the complexity of what you are after.
Could I suggest the following steps (I'm not sure which ones you can do, and which ones you are having trouble with).
Connect to the server and retrieve the list of phone numbers
If the database has a web server front end this might be as simple as sending a get request to the server (see NSURLConnection) and parsing the result. Otherwise you will need to know/tell us what type database you are using.
Store the phone numbers on the device
Use SQLite to store the numbers on the device (See iPhone SQLite Resources)
Check for internet connectivity
Periodically check for internet connectivity, and if a specific time has elapsed since you last polled the server, retry. (See Checking iPhone internet connectivity)
Although you’re probably looking for a native app solution, you can also do this with a web app.
http://diveintohtml5.ep.io/offline.html
I am a new developer iPhone developer, "learning" to be precise. I came across the useful NSUserDefaults (a dictionary in which you can store/restore state even after your application relaunches). Problem with this dictionary will be memory in your case. NSUserDefaults is sort of global to all applications and yours may spoil the show for other innocent applications (like Weather :D ).
To work around this, you can have your application declare a property list file where you store a few numbers (best practise would be the most recent but you can use any selector of choice). Look for an appropriate time in your run loop to store these numbers into your property file and load them when the application starts.
I'm working on an iPhone application that should work in offline and online modes.
In it's online mode it's supposed to feed all the information the user enters to a webservice backed by GWT/GAE.
In it's offline mode it's supposed to store the information locally, and when connection is available sync it up to the web service.
Currently my plan is as follows:
Provide a connection between an app and a webservice using Protobuffers for efficient over-the-wire communication
Work with local DB using Core Data
Poll the network status, and when available sync the database and keep some sort of local-db-to-remote-db key synchronization.
The question is - am I in the right direction? Are the standard patterns for implementing this? Maybe someone can point me to an open-source application that works in a similar fashion?
I am really new to iPhone coding, and would be very glad to hear any suggestions.
Thanks
I think you've blurring the questions together.
If you've got a question about making a GWT web interface, that's one question.
Questions about how to sync an iPhone to a web service are a different question. For that, you don't want to use GWT's RPCs for syncing, as you'd have to fake out the 'browser-side' of the serialization system in your iPhone code, which GWT normally provides for you.
about system design direction:
First if there is no REAL need do not create 2 different apps one GWT and other iPhone
create one but well written GWT app. It will work off line no problem and will manage your data using HTML feature -- offline application cache
If it a must to create 2 separate apps
than at least save yourself effort and do not write server twice as if you go with standard GWT aproach you will almost sertanly fail to talk to server from stand alone app (it is zipped JSON over HTTP with some tricky headers...) or will write things twise so look in to the RestLet library it well supported by the GAE.
About the way to keep sync with offline / online switching:
There are several aproaches to consider and all of them are not perfect. So when you conseder yours think of what youser expects... Do not be Microsoft Word do not try to outsmart the user.
If there at least one scenario in the use cases that demand user intervention to merge changes (And there will be - take it to the bank) - than you will have implement UI for this - than there is a good reason to use it often - user will get used to it. it better than it will see it in a while since he started to use the app because a need fro it is rare because you implemented a super duper merging logic that asks user only in very special cases... Don't do it.
balance the effort. Because the mess that a bug in such code will introduce to user is much more painful than the benefit all together.
so the HOW:
The one way is the Do-UnDo way.
While off line - keep the log of actions user did on data in timed order user did them
as soon as you connected - send to server and execute them. Same from server to client.
Will work fine in most cases as long as you are not writing a Photoshop kind of software with huge amounts of data per operation. Also referred as Action Pattern by the GangOfFour.
Another way is a source control way. - Versions and may be even locks. very application dependent. DBMS internally some times use it for transactions implementations.
And there is always an option to be Read Only when Ofline :-)
Wonder if you have considered using a Sync Framework to manage the synchronization. If that interests you can take a look at the open source project, OpenMobster's Sync service. You can do the following sync operations
two-way
one-way client
one-way device
bootup
Besides that, all modifications are automatically tracked and synced with the Cloud. You can have your app offline when network connection is down. It will track any changes and automatically in the background synchronize it with the cloud when the connection returns. It also provides synchronization like iCloud across multiple devices
Also, modifications in the Cloud are synched using Push notifications, so the data is always current even if it is stored locally.
Here is a link to the open source project: http://openmobster.googlecode.com
Here is a link to iPhone App Sync: http://code.google.com/p/openmobster/wiki/iPhoneSyncApp