There is a very cool iPhone app called Viddy where you can download filters to apply to videos.
How can they pack filters outside the app, and make them available to users via downloading?
One way would be to have an in-app purchase that's just a document that describes an image processing graph. (Think of a nodal graph representation for something like Shake or Nuke.) For example, a glow is often implemented as a blurred image mixed with the original image. You could create a document which describes that processing graph. Once you've downloaded such a document into your app, you can implement it using Core Image filters, or write your own using GLSL, or even just straight CPU processing.
It's pretty simple, they do use shaders and they're downloaded from the internet.
Download iExplorer for Mac, connect your iPhone with Viddy installed.
Check Library/effects folder in Viddy.app. You'll find afx_1_0.xml and vfx_1_0.xml files there.
Download them to your Mac, open them and you'll find filters definitions there along with URL to download them.
An example is SOHO filter. Download this file, open it and you'll see three files there: shader.fx3 where shader is defined, thumb.png for thumbnail and vignette.png file, which is used for this shader as well.
We did use same approach in unnamed application, but we did encrypt all this information along with shaders itself to avoid analysis like this one :)
Encryption, decryption example request in comment
Let's say you have .fx file with your shader (or any other file).
Open Xcode and go to Build Rules where you can define build rule for *.fx files. Set it to run your Custom script: which can look like this one:
ENC_KEY="your-encryption-key"
${PROJECT_DIR}/../Tools/bin/crypt -e -k $ENC_KEY -i ${INPUT_FILE_PATH} \
-o "${BUILT_PRODUCTS_DIR}/${UNLOCALIZED_RESOURCES_FOLDER_PATH}/${INPUT_FILE_BASE}.cfx"
This script produces .cfx file, which has same content as .fx file, but is encrypted.
crypt binary came from this project: download crypt Xcode project.
Download encrypted resource demo.
Copy EncryptedFileURLProtocol.* and NSURL+EncryptedFileURLProtocol.* files into your project.
In app delegate call this to register your protocol [NSURLProtocol registerClass:[EncryptedFileURLProtocol class]];
And now when you do want to open encrypted resource, you have to use protocol encrypted-file instead of file://. This task handles NSURL category from demo project and you can simply use [NSURL encryptedFileURLWithPath:#"/path/to/my/encrypted/file"].
It's pretty simple and you'll find most info you need in sample app (link above). Also you can mangle your encryption / decryption key in application, so, people have to think and the key is not easily readable. Now, when you access encrypted file via this NSURL, it's automatically decrypted for you in app. The decryption key is set in sharedKey in EncryptedFileURLProtocol.m file.
The easiest way to do this is to build the filters into the app itself, and have the in-app purchase simply unlock the ability to use them.
If you wanted to avoid the download time for all the additional images or other pieces needed, you could still include the code in the main app, and just download the extra resources needed. You can use something like Urban Airship's IAP support to host & download the IAP resources. (You might also want to look into new features of iOS 6 in this vein.)
GLSL shaders may be downloaded in source code form and then to be used for processing. It gives very flexible way to create new filters after having app published. From another hand it might be enough just to update (download) additional filter data. For example, Instagram uses same color curve technique for most filters but with different curve data, so it they want, they will be able to update their filters online.
Filter for videos also uses CIImage class like intagram application for images. See the link here:"http://www.icapps.be/face-detection-with-core-image-on-live-video/". Now filters can be download the filter (actually its In App Purchase happening).
Put the purchase/download method right beneath the case:
case SKPaymentTransactionStatePurchased:
[self ...];
so whats happening is purchase of filter for free which can be used on any video. Actually method is enabled to have filter after SKPaymentTransactionStatePurchased.
Related
I need to download images from a website and display them on(?) multiple UIImageView.
Maybe I'll code a php to "read" the directory and search for images, write a XML file and use it as medium. But I'm not sure if it's the best way.
Let's see the options you have to fetch images from a website:
Fetching HTML and Parsing the HTML to find the images (on the iphone). Then downloading the images.
Writing a script (maybe PHP) that writes all image links to an XML file (or JSON), and then fetch the output of your script with all the links.
If you choose option (1) you'll need NSURLConnection to fetch data asynchronously (without blocking the UI). I would also use TFHpple to parse HTML using xpath queries, see this tutorial for help. Finally to fetch the images using their URLs you can use SDWebImage, SDWebimage also provides caching so your app will not download the same image multiple times.
The bad side of using option (1) is that any change in the Website you're getting the images from will break your app and you'll need to issue an update to the app store in order to fix it.
If you choose option (2), your app will be easier to fix if the website changes, you'll just need to modify your script.
If you go with option (2) you'll probably need NSURLConnection, NSXMLParser (or a third party XML parsing library) and to download the images I would recomend SDWebImage again. I would also advise using JSON (and NSJSONSerialization) instead of XML, just beacuse I find JSON easier to parse.
Yes, it will be very good if you write some php script to get image list (list of image urls).
After getting such urls you can asynchronously download and show them in image views. Look here for such async image view implementation
I have an iOS application, which stores all downloaded *.pdf files in its cache. Is there a way to prevent this data from extracting? Encryption or something else? Thanks in advance.
There are quite a few ways to encrypt files, and I'm sure everyone will have an opinion on the best way to do so.
In a project I've recently been working on, we've been using CommonCrypto (https://github.com/AlanQuatermain/aqtoolkit). Just take any NSData, encrypt it, and save it to a file, and vice versa. You can even write an easy Transformer by subclassing NSValueTransformer, which abstracts all of the encryption to one spot and you will never have to worry about it again.
You can protect PDF files with a password. I assume you create the PDF files not within the application but externally. For example you can use Preview.app in Mac OS X to secure existing PDF files with a password (Hit Cmd-P, then select PDF in the print menu and there you can set security options. Or even more simple: in the menu choose Export...).
In iOS you can then open the PDF files like this:
CGPDFDocumentRef documentRef = CGPDFDocumentCreateWithURL((__bridge CFURLRef)[NSURL fileURLWithPath:filePath]);
if (!CGPDFDocumentIsUnlocked(documentRef))
CGPDFDocumentUnlockWithPassword(documentRef, password);
...
There are actually 2 Documents folders in which your app can store content. One can be extracted, and one is private. Check the accepted answer in this ticket.
Access files in "private Documents" folder transferred with iTunes
Assuming you want the PDF files from getting extracted on jailbroken devices, the most straight forward approach would be along the following lines:
generate a random string during the first launch of the app
save the random string either in NSUserDefaults in state file inside your own app's sandbox
using this random string create a secret key using a deterministic but hard to figure out algorithm
use this secret key, which you don't store anywhere but always generate on demand, symmetrically encrypt your buffer with AES or something similar
You would probably find the source code here very helpful.
I have a Default.png which includes a version number on it. Every time I update my app, I have to change it both in the lite and full version's default.png and default#2x.png. Hassle, no?
I'm pretty sure I've been going about this the wrong way. What should I do instead? (I would like to show a version number on launch, not just nix it altogether.)
Compile-Time Image Compositing
If your logo doesn't need to change other than the version number, then you can use your graphics library of choice at compile-time to refactor the png. Pseudo code below:
Pseudo-Code:
UpdateLogo(String logoName, String version)
{
WidgetImage MyLogo(logoName + ".png");
MyLogo.DrawText(800, 650, version);
MyLogo.Write(logoName + "Final.png");
}
UpdateLogo("Logo.png", "Version 1.0.0");
Compile that program and keep it around as a custom build tool. Then whenever you need to build your application you can compile Logo.png into LogoFinal.png. If you need help using XCode or other tools to generate image files I suggest you search for image manipulation tools separately from "dynamic versioning".
Ideally your version string will use constants defined in an easily-editable table or controlled by your build system. At the very least it will save you from opening up Photoshop every time you need to build your app.
For Display in a Running Application
You should be using a font to draw the version number on top of the logo. Then you can just include a resource file that is text-based and can be easily updated by automated tools for each build.
Sources
Can you create custom build rules for XCode based on file type?
Apple's Human Interface Guidelines say that the Default.png shouldn't be used as a splash screen; it should represent all of the UI controls the application will show, but without any localizable text or content. (Think of how the the built-in apps like iPod and Contacts behave.)
If you're doing it for a client and they demand it, you can always use the "But the app store might reject it for violating their terms!" argument.
Of course, this doesn't apply if you're not submitting to the Store or if you just don't care. :)
A technical add-on for the people posting above: make sure that any png compositing you're adding to the build process runs before pngcrush executes, so that you're not replacing an optimized image with a script-generated (and likely unoptimized) one. You may also run into weird issues if you try doing it after pngcrush runs (it not displaying), anyway.
I need to define a processing rule for web data in iOS and thought it would be a good idea to pull the processing rule as a script file from my server and execute it on the iOS device, since the web API I'm interacting with might change URLs or response syntax and I need to be able to fix such issues fast and cannot rely on pushing an update (takes forever).
I wanted to do it with a small JS file that is pulled from my server every once and a while, but unfortunately iOS doesn't include the JavaScriptCore framework.
Are there other options?
Apple developer agreement will not let you run a downloaded, interpreted script, on the device.
Your best bet is probably downloading a data structure (potentially in JSON format) and parse that and take some predefined actions in your client code based on that, rather than trying to execute the downloaded code directly.
You can let a UIWebView run a Javascript snippet, or you could use another scripting language like LUA (don't forget to add LUA for this). The real problem is: You are not allowed to download code from a webserver or somewhere else. Everything must either be already on the device, or calculated at runtime.
Depending on the information that you want, you could use an XML file that includes the new URLs and parse it, but I don't know if this fits your need.
You can compile JavaScriptCore into your app, evidently, and have it approved by Apple. However, as Mehrdad notes, any scripts run in the app must already be in the app at the time the app is reviewed.
i am making an app in which i have to upload an image/video file to the server...i want to know what things i needed to do this..?and i also have to show the progress bar while image is uploading...how can i do this..?
can you write some code snippet on how to upload file to server...?
If you are using http to transfer files.Allseeing-i have a great api for this called ASIHTTPRequest, its feature rich, well documented, easy to use and it supports file transfer tracking.
They have code examples and a description on how to include it in your projects.