As mentioned in another article, I ported one of my apps to BlackBerry 10. In retrospect, I could have done this a lot sooner. But three months ago, the dev tool and documentation were not as mature as now so maybe that also hampered my progress.
I came from the burning platform that is Nokia. So my app was pure Qt/QML with heavy use of Qt components for UI. If you are of the same background, I hope my experience in porting to BB10 might be helpful to you.
First of all, you need to decide upfront which development environment you want to use:BlackBerry's
There are different issues for the two approaches, in my case they are:
- Cascade: Learning Cascade, rewrite UI, more #ifdef in C++ for blackberry specific codes
- Pure Qt/QML:
- I couldn't get QML Text component to use the text style I wanted.
- Have to work around the lack of native BB10 Qt components, either by compiling Qt components for BB10 (there are pre-compiled libraries available on BlackBerry developer forum, but I never succeeded in using them. Nor have I been able to compile them from source), or by re-implementing the UI elements (which was not feasible for me....).
Whichever route you choose, you need to registered for code signing keys. I will skip the step since you can easily find reference on it. For pure Qt/QML, QtCreator 2.6 is good enough and if not for the font issue I encountered I might choose that. I ended up working with Cascade, and one thing I learned about Cascade was I felt the QML part was at times an afterthought. QML is kind of like an wrapper, but it is even more so in Cascade. Instead of thinking that you are working in javascript, think of using Cascade QML as if you are working in an "virtual machine" encapsulated in Qt C++. One powerful thing I learned is, the "attachedObjects" property is the bridge to expose Qt C++ objects directly into QML [1]. So instead of searching for QML elements to use in... well QML, you search for Qt C++ class to plug into attachedObjects scope. Or you can extend a class in C++ then register it into QML. The concept is different for me, and after stop thinking "why did BlackBerry implement like this," I started getting better progress.
Between beta and gold SDK, BlackBerry has added a few very useful elements in C++. This means that Qt elements such as QueryDialog{}, Sheet{} etc. have comparable elements in Cascade, just that you need to instantiate them in attachedObjects scope, not elsewhere. Gold SDK also simplified list manipulation and now header/data are just a string definition apart. Speaking of list manipulation, Cascade has separate DataAccess/DataSource class to populate list. In theory they are convenient but in reality, I found the lack of callback functions can limit their usefulness, e.g. if the data fetched is decorated with // for comment the DataSource ignores the data. Also Cascade uses indexPath, a QVariantList to specify the hierarchy within the list, and this can be confusing when you have headers. Cascade list provides more complex use cases, for example it offers context menu. One problem you will immediately find is that context menu seems to be isolated in its own scope and cannot access anything above it if you use "id.function()" syntax. There is a solution [2], and I found that context menu does have access to ListItemData property [3]. All API document can be conveniently found at [3], and a few useful UI component tutorials are at [4][5][6]. If you encounter any problem, first search BlackBerry developer forum. It is full of information and people there are willing to help.
Last but not least, there are free in-app icons available for BB10, courtesy of Myers Design [7]. I remember reading there is another one, but Myers' icons are awesome for me so I didn't search further.
Hope the above info is helpful. If you have questions, don't hesitate to leave a comment! Happy coding!
Reference
[2] "ContextActions inside ListItem can not access ContextProperty in QMLDocument"
[3] "Cascade API documentation"
[4] "Cascade System Dialogs"
[5] "Cascade Sample Apps"
[6] "List Manipulation"
[7] "Free BB10 in-app icons"
