I've experimented with several ways on seeing if I need to update my user's UITableView data source only if the server one is newer. Over the past few years I've done these scenarios: 1: Having a seperate .txt file with a character as the version # then simply comparing them through code and downloading the new .plist, then saving that .txt to the user's NSDocumentDirectory along with the .plist to compare again in the future, and 2: Actually checking the server's file modification date, which worked even better, as there was no .txt file to download along with the .plist (the less stuff to download the better)
But, now I want to try a different way to account for the fact that I ship a .plist file in the App Bundle. Since the .plist file creation date is always later then the server date for new users, they don't get the new .plist file, whereas older users of the app get the new file. Sure, on the first app launch I could grab the server's modification date and overwrite the app's since I copy it from the main bundle to the NSDocumentDirectory, but I don't think I want to go that route, as I've never liked checking launch counts.
Basically, it needs to continue to be lightweight in network request time and be reliable like it's been for me. I was thinking about creating a version # key in my .plist and simply comparing that with the local .plist, but I highly doubt this will be as lightweight, as I would have to download the whole .plist into an NSDictionary first before I can compare the key values.
I'm really sorry this post is long, and I appreciate your help!
Why not ship the app with out the data_source.plist file and download it on first launch, or any other time it does not exist on disk (you never know). After that, you could send a HEAD request and check the modification date (maybe even the e-tag), and download as necessary.
UPDATE:
Depending on how much control you have over the server, you could add a hash of the file to the response headers (as mentioned in the comments: MD5,SHA*) along side Last-Modified.
You could add the data_source.plist to the bundle at build time, along with last_modified.plist where you can set the hash, last modified, and any other meta data you want, as starting point.
Checking for updates could look something like:
Send HEAD request for http://server.com/data_source.plist
Pull Last-Modified (and hash if you can send it) from the response headers
Validate against corresponding values in last_modifed.plist
Download updated data_source.plist if needed
If the download was successful, update last_modifed.plist with new meta data (last modified and has, be sure pull this from actual download response headers).
This way, the user has something to start with, and the app can download the resource when needed.
The advantage of a HEAD request is it is light weight since there is no message body, but returns the same response headers as a GET request. It is a common method to check if a resource has been updated. The trick with your scenario is to get a starting point onto the device at build time.
Related
I am using FineUploader and it works just fine for my application needs. The files end up where I need them etc.
However once the file is uploaded, I really don't know what the file actually is. For instance the file could be a resume, a cover letter, a release of information, etc. For that I will need to "attach" additional metadata that relates to that file.
Is there a way to add some sort of a select box, where the user will select a category (before the upload process begins) so that the file can be identified by that category? The filename, size and other information gathered during the upload process are already stored in the database.
Any pointers are more than appreciated.
Edit: Duplicate Submit multiple form fields for each file in FineUploader
I wanted to auto fetch data(gold price) from a website and update a variable. Do i have to load the whole .html file in a string and find the price? Is there any other way? Even if I updated the variable, how do i save it, so it retains it's updated value(price)?
Do i have to load the whole .html file
in a string and find the price?
Yes
Is there any other way?
Only if the web site also provides an API that gives you access to just the data you need.
Even if I updated the variable, how do
i save it, so it retains it's updated
value(price)?
A variable will keep it's value until you change it. However if you want to preserve it even when the user quits your app, so that it starts again from the same value, you could save it in NSUserDefaults for example.
Do be aware however, that the data is almost certainly copyright, you can't just scrape data from a website and publish an app based on that data without considering the legal perspective. Price data is normally owned by the exchange and you will need a license to re-publish it.
I've been trying to figure out how to download multiple files in a row based on the SimpleFTPSample provided by apple. Basically, I'm filtering what the user can see when they browse an ftp server, but when they select a certain file type, I want it to automatically check for another file of the same name with a different extension and if it exists, download it as well. I can't seem to get this second file to download no matter what I do. It seems strange because if I select two files in a row in my tableview, it downloads both of them just fine. Any ideas?
Edit:
It's just the SimpleFTPSample from apple.developer.com, all I did was create additional NSInputStream and NSOutputStream objects and I created a new _startReceiveFile method that gets called from _startReceive if I'm downloading a file instead of getting a directory listing. _startReceiveFile is the same code for _startReceive in the file download code for the sample project, except if the file to download has a certain extension, it also downloads an additional file with the additional stream objects. Let me know if I need to clarify more or try to put together a clear example.
Well, since there were no takers, I'll just post my solution here. I've abandoned trying to download two files at once. Instead, I just keep the ftp browsing window open and only handle the opening of the file once both files have been downloaded (user has clicked on each one separately). It's not what I wanted, but it will work, at least until I can figure out how to get two files with one request.
I wrote a game that I plan on updating soon. The game generates a scoreboard when the application starts, if there is no scoreboard file present.
If people update to my latest version, will the scoreboard file (that's generated by the code itself, not a file that comes preloaded in the app) be deleted?
If so, is there any way to avoid this without any coding previously required?
The updated version of your app will simply replace the existing version's bundle - any files you've written to your app's document area will remain intact.
As such, you simply need to check for the presence of the file within your app's document area as per usual and write a "new" version if none exists.
If the file is within your applications bundle, it will be deleted. Files saved with Core Data and NSUserDefaults will not. I've never personally written a file to the disk, so I don't know where the default write point is. You'll have to find this out yourself.
Happy coding,
Zane
I have an .xml file that is going to be shipped within my app.
This file contains values that are read from it and saved as an array when the app launches.
Each time the app is run, I want to check with the server if there is an internet connection. If so, I want to get the newest version of the .xml file from the server and replace the one that I currently have saved in my app (this way, the next time the user logs in and doesn't have internet access, he/she will be able to use the old (yet most up to date) data).
What is the best way to do this?
Thanks,
The best way to probably do this is to copy the XML file from the app bundle to a location in the app's sandbox, e.g. the Documents folder. Thereafter you can update the XML content as necessary with newer data from the server. The copy is necessary to allow you to write to the file, since you cannot change the content of your app's bundle because it is signed.
Alternatively, if the data is simple enough, you can just save it to user defaults on first launch and change the defaults on subsequent updates
I might skip the XML altogether, unless it contains a baseline of default settings, and just sync user defaults over the Internet. You can't modify files in the bundle, so your only option would be to copy over a "default-settings" XML file to the application's Documents folder to make it editable.