here's the thing: I download a bunch of data in JSON format. I put that into an array of dictionaries. Then, I save to disk. One dictionary stores a link to some image. What I would like to do is to store also the actual image (not the link!) along with rest of the data. How would you start? Which way to go?
I would download the image and save the local path alongside the URL path.
However, if you're going for one big file, you could always base64-encode it.
I think using the filesystem directly and saving your local path would be more efficient and effective than one monolithic file, as you'll save a lot of parsing and encode/decode time.
I suggest you to start from this tutorial : SimpleFTPExample
Related
I want to know if there is a 'right' way to make file uploads through custom tools.
I've seen the https://confluence.sakaiproject.org/display/BOOT/File+Uploads+with+RSF guide and it seens ok, but It stops with the file in memory with no further info. I can built a random file upload code but I want to make it Sakai-friendly (Using ContentHosting and Resources service?)
Any hints?
Thanks
The link you provided for the first part is a good example of how to get the upload initially processed. Going through RequestFilter will get your files validated, but you can use whatever method you want to upload it.
For the second part, I'd look at the ContentHosting webservice (createContentItem) for an example of how to add a file from a byte[] in memory after you've uploaded it.
These methods in ContentHostingService also accept InputStream as a parameter as of 2.7 (KNL-325), so you don't have to store the entire file in memory and can stream it as you're uploading, which you should do if the files are of any reasonable size.
I find many similar question but i didn't get solution for this.
Is it possible to upload some file like image, document, zip file to upload on iCloud programmatically?
See table 4-1 in the documentation:
How do you manage the data? Manage files and directores using the
NSFileManager class. Open, close, read, and write files using standard
file system routines.
So if you can create a file, you can store it in iCloud. But remember there's a finite, relatively small amount of space available.
iCloud can handle all kinds of files. So if you want rot use an obscure file format or invent your own, go for it. It only can to be converted into a byte stream/NSData, but then again, what isn't?
Check this tutorial walkthrough app. It shows how to create, modify and delete files for iCloud.
http://github.com/lichtschlag/iCloudPlayground
any recommendations for saving four strings into an own file format that is read by the application and can be shared?
In my app, you will be able to enter some text in some boxes and the app shows a view with an background image and those strings. Now, I am already able to save this as a picture, but I actually want to save it to an own file format so that you can save different files that can be modified afterwards as well or even exchanged via email and opened from another iphone with the app.
Now, I wrote the code for accessing the documents folder of the app, as well as saving and deleting. Thing is, i dont know how to store those strings in a file (perhaps in a xml?) and read them easily afterwards from my application.
For the exchanging part, I found that link which would be a nice feature indeed: http://iosdevelopertips.com/cocoa/launching-your-own-application-via-a-custom-url-scheme.html
Parsing xml seems not that difficult (never done it before): http://ipad.about.com/od/iPad-App-Dev/a/How-To-Parse-Xml-Files-In-Xcode-Objective-C.htm
If it's only a small bit of infomation then the easiest way to store your data in a file would be using a plist - there's a good tutorial here - http://www.icodeblog.com/2009/02/14/loading-data-from-plist-files/
In addition to the plist, you could also do the following approaches:
1) simplest - open a file in your documents directory, write the 4 strings (using whatever delimiter/end of string marker is useful - carriage return?) and overwrite them each time through. (i.e. it's your file, you can format it how you like)
2) mildly harder - use Apple's NSArchive to pack and unpack the strings.
3) possible overkill - store them directly in a SQLite database
4) major overkill - store them in CoreData.
Of course, the "overkill" options also provide you with extra features which may be of use if your app functionality extends beyond what you've outlined.
By sharing, I would think that simple copy and paste might be enough, but there's also sending it via email, or tripping another app's URL scheme to make it open it and sending the strings as part of the URL. You'd have to know that the other app would be able to interpret your strings as part of the URL, so you might have to write it yourself.
Okay guys I found that very nice method in the NSString documentation:
–writeToFile:atomically:encoding:error:
I think I am gonna separate my strings by /n and save them to a .txt. When I am gonna read the file afterwards, i am getting the string, divide it to substrings. That will do it, I guess.
One last question: Is it possible to replace the content of my file so that I won't need to create a new file every time i want to change something?
Thanks!
My iPhone (actually, iPad) app creates documents that consist of several images, plus a bit of metadata. What's the best practice for storing these sorts of documents on disk? I see two main options:
Create a folder for each document, and store my images as separate PNG files within the folder (plus another little file for the metadata).
Create a single file which contains all images and metadata.
But I'm not sure how to easily do option 2. I think I can convert my images in PNG format to/from NSData, but then what? I'm still a newbie at Cocoa, but I believe I saw something about stuffing mixed data into some NSSomethingOrOther and having this write itself out to disk, and read itself back in later. Does this ring a bell with anyone? And, will it work with large binary blobs of data like my images?
Or would you recommend I simply go with option 1?
Simply go with option1. It's clean, elegant, and simple to implement. You could even use (a subset of) HTML.
TIFFs and PDFs can have multiple pages.
Creating a document centric iPhone/iPad application with own file format using ZipArchive
I have to link a date and a name to some jpegs that I am including in my bundle, or possibly downloading from my own server to the Documents folder. Is there a way to extract EXIF data easily?
If so, then I will use EXIF to store this info. If not, then I will have to create a database or flat file that maps my extra data to the image file.
Keep in mind, these are not photos the iPhone has taken and is providing via UIImagePicker or from outside the sandbox. These are photos that I am including with the app or downloadig to the Docs folder myself. The important point here is ease:
Is it easier to
read EXIF file from my image files
have another file that keeps track of
the image file and the associated
data (could be sqlite)
Thanks!
You can try using iphone-exif toolkit to extract the data. However, it's licensed GPL and if your app is commercial you'll need to negotiate a license deal. If that's not viable then you may want to go the external meta-data route.
The actual EXIF data is stored in the form of a small TIFF file with EXIF-specific TIFF tags for information that doesn't have a home in the TIFF specification. When placed in a JPEG file (really a JFIF bitstream), it is stored in a JPEG APP1 marker which limits the total size of the EXIF data to just a bit less than 64KB.
It shouldn't be that difficult to locate the APP1 marker, confirm it contains EXIF data, and then parse out a specific collection of EXIF tags with fairly brute force coding.
One example you can look at is exiftool which does just that, and is written in Perl and open source under the same terms as Perl itself.
If these files are purely for use in your own application and will not be reused in other tools by the user, then there is some mileage in storing your data as XML/JSON in the comment segment 0xFFFE. As mentioned before you get just short of 64k to play with.
The beauty of using the comment segment is that it should be preserved by image editing tools, is quick to access (because you do not need to traverse the IFD blocks that store EXIF data, you just read/write a text string with 4 byte type/length header) and is human readable/writable in a graphics app.
I would avoid storing the associated data in a db if practical, so that you don't risk the db becoming out of sync with the available files.
I use ExifTool
embedded in my app. Works a treat.