I'm working on UIDocument application and I'd like to show the user a preview of the document before he opens it. I can render that preview into an image when the document get's closed. But where should I save that image? In an other file? or is there a designated way to do this?
Right now I'm developing it without iCloud support. But I want to have a solution that would work with iCloud too. The UIDocument is a UIManagedDocument. But saving the image into the database would make it kind a pointless. Because then I have to open the document before I can get the preview.
What do you recommend here? Where to put a preview for a UIManagedDocument?
You can store your documents in your ubiquity container's Documents directory and document preview files in the container's Data directory.
If preview file names will be based on the documents names you will be able to use metadata query result to get the document names and then resolve document preview urls.
This way you could download the document previews only but not the whole document.
I don't know about UIManagedDocuments, but in case of a UIDocument I would recommend using a NSFileWrapper as file format (where the document is actually a bundled folder) and save the preview within the document, as "Preview.jpg" (or .png) inside a folder labeled "QuickLook".
This way, you'll get the preview in Finder on the Mac as well (for free).
Of course this may or may not be an ideal solution (also depending on if your document is text-only). But it might be a good hint for working with previews for UIDocuments in general.
You should save an image under (app_directory)/Library/Caches. That way iCloud won't affect your app.
Related
I'm developing an app that I want the user to be able to take a screenshot with a button (this works, but it's stored to camera roll). I have a need to keep history of these screenshots along with site name, etc.
I've been reading that it's not recommended to save binary data in a sqlite db, so I've stumbled across core data. I'm still learning, but one question that comes to mind is this. Some recommend to save the filename to coredata and then save the image to document directory. I want to read the data back into a table view controller and have the image part of the cell. Will I need to resize the image to the size I want when reading in, or will it automatically size down to what it needs?
Also, when saving to document directory, are those files accessible from the camera roll? I don't want them to be and I'd like to give the user the ability to be able to delete them with the tableviewcontroller.
Please let me know if I need to expand on anything. I'm learning Swift, so I'm sure I missed something.
You should not save it to the Documents directory.
You should instead Allow External Storage of the attribute. Core Data will take care of storing it for you. This is explained in the answer by jansenmaarten to this question.
We are writing some program to display documents on iOS. I think that there are a lot of confusion on the web about what type of documents which iOS UIWebView could display. Generally people refer to Technical Q&A QA1630 Using UIWebView to display select document types to see that all the MS office 07+ files (such as docx, xlsx, pptx) could not be displayed, however actually that is not what we see from testing. Actually we are able to display docx/xlsx/pptx document at UIWebView either loading from a remote URL, local file or in memory (loadData, here the baseURL can not be nil on simulator, see this link). Of course We are testing on latest version of iOS on iPhone simulator, it might be that the support was not at older iOS. At this point, We don't know that yet. If you know, please let me know.
However right now, We have one issue to display document at UIWebView by using custom URL for security reason. I did the custom URL by following the code here: protecting iOS resource. We could display xls, doc, ppt, pdf file, but not docx/xlsx/pptx, We got some error like this:
EXCEPTION SFUZipEndOfCentralDirectoryError: Could not find the end of central directory record
We tried to debug and could not figure what's to do here. Do you see similar error here? Could anyone shed some lights on this? Thanks very much.
It looks like the document you're trying to open might be corrupt. docx, xlsx, and pptx files are actually zip files containing a bunch of XML documents and other data. Check if you are able to uncompress the file on your computer by renaming it to .zip and then unzipping.
I have an app I'm designing that will allow for lots of PDF viewing. There are a lot of different languages available, and so if I were to include all of them in the app, it would be like 100+ mb in size which just won't fly.
So I'm thinking that I am going to put the pdf's on my server, and access them with a direct download link like this:
http://mysite.com/pdfs/thepdf.pdf
Which will return the exact pdf I want. So I'm wondering how I can go about accessing these resources as I download them on the fly?
I imagine I need to save the pdf's to the app resources folder? And then when a tableView row for the pdf is selected, I check if the pdf is in the resources folder (how do I do that?), and if not, pull it down off the server, and load it into my view?
I think I have an okay idea of what I need to do, just not very clear on the code to do it. Can anybody post the code for accessing the resources folder (if that's actually what I need to be doing), and maybe the code for how to check if something is in the resources folder?
Thanks!
Have you considered using a UIWebView to view the PDF instead of downloading and loading it yourself? UIWebView should take care of caching, so you won't have to worry about that.
Assuming that a UIWebView won't work, to download PDFs and see if they exist, you need to store it in the Documents folder. The resources folder cannot be altered after you submit your app to Apple, but the Documents folder in your app is completely fine. To access it, I would actually recommend ConciseKit, which can be found on GitHub. It gives you a helper method to access your app's document directory. The helper method is
[$ documentPath];
Then you can get the path for a file by doing
[[$ documentPath] stringByAppendingPathComponent:#"file.pdf"];
So that is how you get a path to a file, to check if it exists, you want to use NSFileManager.
[[NSFileManager defaultManager] fileExistsAtPath:#"path from above"];
My image editing app is saving some important data in the documents directory. In a tutorial I was reading this:
iTunes will then display anything you
save to the Documents directory in
your app to the user, when they go to
the “Apps” page in iTunes and scroll
to the bottom:
I have a subfolder called userImages and it would be clever to restrict file sharing only to that folder and not to everything in documents. Otherwise the user would accidently (or on purpose) mess around with files that the app depends on to work properly. This would be bad.
Is there a way to restrict it to a subdirectory in documents?
No, what you should do instead is store anything you do not want users seeing in the "Library" directory for the app. Check here for a list of places you can store data:
How can I get a writable path on the iPhone?
Can someone help me find where CoreData is storing the SQL file it creates in iOS applications?
So far I've tried "Show package contents" on the .xcdatamodel file and also the .xcodeproj file...No dice!
Is there an editor for looking at the contents of these SQL files?
Cheers.
-A
The url parameter of [NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:url:options:error] specifies the location of the file. Find this call in your code and see where you've stored it. XCode templates will put it into the top of your application documents directory, but you can put it anywhere you like.
Note that Apple considers the contents of this database to be opaque and non-user-modifiable. Playing with the data in your store is likely to cause issues with Core Data.
It's typically saved into your application's documents directory, with the name of your data model.
So, for example, if my data model is called AppData.xcdatamodeld, it will be AppData.sqlite inside my app's document directory. You shouldn't really need to touch the .sqlite file though.
Hope that helps!
Core Data editor --> http://christian-kienle.de/CoreDataEditor/