Way To Modify HTML Before Display using Cocoa Webkit for Internationalization - html

Question

In Objective C to build a Mac OSX (Cocoa) application, I'm using the native Webkit widget to display local files with the file:// URL, pulling from this folder:
MyApp.app/Contents/Resources/lang/en/html
This is all well and good until I start to need a German version. That means I have to copy en/html as de/html, then have someone replace the wording in the HTML (and some in the Javascript (like with modal dialogs)) with German phrasing. That's quite a lot of work!
Okay, that might seem doable until this creates a headache where I have to constantly maintain multiple versions of the html folder for each of the languages I need to support.
Then the thought came to me...
Why not just replace the phrasing with template tags like %CONTINUE%
and then, before the page is rendered, intercept it and swap it out
with strings pulled from a language plist file?
Through some API with this widget, is it possible to intercept HTML before it is rendered and replace text?
If it is possible, would it be noticeably slow such that it wouldn't be worth it?
Or, do you recommend I do a strategy where I build a generator that I keep on my workstation which builds each of the HTML folders for me from a main template, and then I deploy those already completed with my setup application once I determine the user's language from the setup application?

Answer 1

Through a lot of experimentation, I found an ugly way to do templating. Like I said, it's not desirable and has some side effects:
You'll see a flash on the first window load. On first load of the application window that has the WebKit widget, you'll want to hide the window until the second time the page content is displayed. I guess you'll have to use a property for that.
When you navigate, each page loads twice. It's almost not noticeable, but not good enough for good development.
I found an odd quirk with Bootstrap CSS where it made my table grid rows very large and didn't apply CSS properly for some strange reason. I might be able to tweak the CSS to fix that.
Unfortunately, I found no other event I could intercept on this except didFinishLoadForFrame. However, by then, the page has already downloaded and rendered at least once for a microsecond. It would be great to intercept some event before then, where I have the full HTML, and do the swap there before display. I didn't find such an event. However, if someone finds such an event -- that would probably make this a great templating solution.
- (void)webView:(WebView *)sender didFinishLoadForFrame:(WebFrame *)frame
{
DOMHTMLElement * htmlNode =
(DOMHTMLElement *) [[[frame DOMDocument] getElementsByTagName: #"html"] item: 0];
NSString *s = [htmlNode outerHTML];
if ([s containsString:#"<!-- processed -->"]) {
return;
}
NSURL *oBaseURL = [[[frame dataSource] request] URL];
s = [s stringByReplacingOccurrencesOfString:#"%EXAMPLE%" withString:#"ZZZ"];
s = [s stringByReplacingOccurrencesOfString:#"</head>" withString:#"<!-- processed -->\n</head>"];
[frame loadHTMLString:s baseURL:oBaseURL];
}
The above will look at HTML that contains %EXAMPLE% and replace it with ZZZ.
In the end, I realized that this is inefficient because of page flash, and, on long bits of text that need a lot of replacing, may have some quite noticeable delay. The better way is to create a compile time generator. This would be to make one HTML folder with %PARAMETERIZED_TAGS% inside instead of English text. Then, create a "Run Script" in your "Build Phase" that runs some program/script you create in whatever language you want that generates each HTML folder from all the available lang-XX.plist files you have in a directory, where XX is a language code like 'en', 'de', etc. It reads the HTML file, finds the parameterized tag match in the lang-XX.plist file, and replaces that text with the text for that language. That way, after compilation, you have several HTML folders for each language, already using your translated strings. This is efficient because then it allows you to have one single HTML folder where you handle your code, and don't have to do the extremely tedious process of creating each HTML folder in each language, nor have to maintain that mess. The compile time generator would do that for you. However -- you'll have to build that compile time generator.