I am making an app render the cloud points on different layer. For now I am consuming the data as .txt file converted from .las file. My question is: is there a way or lib to directly consume the .las format on iOS device? I searched about the libLAS (http://www.liblas.org/) but don't think it will work.
Thanks
Try LASlib of LAStools. It compiles without dependencies and also reads compressed LAS aka LAZ.
http://github.com/LAStools/LAStools/tree/master/LASlib
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I am downloading a mp4 file with my iOS app, it works fine using
NSData dataWithContentsOfURL
but i need to updated only if the file has been updated,
can I check the file headers? or what is the best way to determine if the file has been updated so I downloaded it again?
Thanks
You can access the metadata using the http HEAD request, as explained in this SO answer. You'll need to create some sort of parser to pick out the information you need, though. Note that this might not work with every server, depending on how it has been set up.
If you have control of the server yourself, I'd recommend using a php script to output the date the file has been last changed, which you would call before downloading the file.
Personally, I prefer placing a manifest file (usually a plist) alongside the file in question, as it can hold even more data, for example metadata for several files, the number of entries in a database and the like. A backdraw of this approach is that you'll need to keep this file up to date, though. But often, that is worth the while.
Lastly, as rckoenes has mentioned, dataWithContentsOfURL is not a very good way to download files, espcially large ones. You really should be using some sort of datamanager class, which manages a NSURLConnection.
Are there any good SDKs available on iOS that will not only display a PDF, but will show it as it is downloading from a web source? It is perfectly fine to use a paid for library as long as it is commercial-friendly.
To clarify, the SDK must be able to show partial files as they are downloading, whether I provide the stream or otherwise. I would like to avoid CGPDFScannerRef due to how low level it is -- I have tried FastPdfKit as well but it will only show the whole PDF after it has been fully downloaded. Any ideas?
PDF is a structured format that consists of different types of data blocks such as TOC, text, fonts, colors, annotations and information about these blocks is saved at the end of the file. So this makes it impossible for CGPDFDocumentRef to open the pdf without all the data available.
However you can get around this limitation by linearizing the PDF file so that the metadata information will be put at the beginning of the file. I'm not sure but I think you can then use CGDataProviderCreateSequential in combination with CGPDFDocumentRef to parse a partially downloaded PDF file.
I have an app that uses copyrighted images that I have permission to use. If a user downloads my app onto their computer using iTunes, they can basically unzip the app file (change filename to add .zip, unzip then show package contents), and see the images.
Is there a way to prevent this? Or am I wrong about this?
To the best of my knowledge there is no way to stop this method of accessing the images; the only alternative I can think of is to encrypt the images and store the encrypted files in the app. Then decrypt the images at runtime.
This won't stop the most determined adversary but would stop people accessing the images without some effort on their part.
A determined adversary will likely be able to get at any files used by an app on a device in their possession.
To defeat a lazy adversary, you might only have to change the file names into something they won't recognize as an image file. Or change a few bytes containing the file type signature at the beginning of each file, rendering the file corrupt. Your app can copy them into a temp file and fix the signatures to display.
Apple reportedly encrypts an App store distributed app's compiled C code. So another possibility might be to embed (portions of) the copyrighted images as hex data inside your source code.
I'm about to write an app for iPad2 to make website offline available.
Several Publications (consisting of one HTML, one Javascript an many PNG Files) need to be downloaded to the iPad for offline Viewing.
Is there a good unzip-class for iOS so that i could download a zip from server and unpack it to a subdirectory in Documents Folder?
http://code.google.com/p/objective-zip/ looks like the right code for your needs.
If compression doesn't matter, the untar algorithm is pretty easy to implement. Either you keep it as plain C, or you adapt it to objective-C.
Reference: http://code.google.com/p/libarchive/source/browse/trunk/contrib/untar.c?r=1143
For a project we need to download and save pdf files on an IPAD device for offline use through an AIR for iOs application.
After a lot of searching I haven't found much information on this subject. My question is, can it be done, and if so, can you provide us with some pointers to lead us in the right direction.
Thanks for your time!
Sure, first you check if you can access the web - can use a class like air.net.URLMonitor, if you can you can set up a URLStream instance.
You get data while its downloading the file using the progress event, write that out to a File instance using the FileStream class.
To display the PDF file you can use a StageWebView or HTMLLoader.