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OverviewFelgo 3 Support (Qt 5) › Release, performance and qt commercial licence

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    HI all,
    I need some clarification for release “mode” and performance.
    In general I come across some issues with iPhone and missing JIT and also don’t fully understand what extra v-play gives you in release mode.
    Here we go:
    1. From the v-play docs(http://felgo.com/doc/vplay-publishing/), in release mode, you can build/include all qml files into one binary file.
    Does it affect performance(improve)? Or it is just for security reasons?
    How secure is it, is it possible, for example, that all 3rd party app keys I use in qml files can be read by users of the app?

    2. I am really confused about JIT in Qt and platforms which block it.
    From what I read, the reasons I do not get JIT in iPhone is some file which can potentially undefined it(special variable).
    It looks I can delete that bit from that file but I need Qt commercial licence otherwise I violate the licence.

    Does v-play help with JIT in iPhone or there is nothing extra from v-play in this area?
    3. There is also qt quick compiler which looks like is only in Qt commercial licence. Is it worth to use it if I use v-play?

    4. What do you do before you release a game/app, is there any special step that is worth to do using v-play, which I can miss?


    Best regards,


    Felgo Team

    Hi Marcin,

    Thanks for the questions!

    1. Putting QML and JS files into a binary resource file and use that instead of the QML files within the app bundle also gives a small performance improvement, as files do not need to be loaded from the file system. The level of improvement depends on the project size and structure but is reasonably small.
    2. The JIT information you get during starting up an iOS app is more from a Qt build viewpoint. To enable JIT you would have to rebuild Qt iOS libraries from scratch, so this is not a simple configuration variable you can change when using existing Qt libraries. The reason for disabled JIT-support on iOS is a more legal one, Apple does not allow apps on the App Store that create binary code on the fly and execute it. Recompiling Qt with JIT support does not necessarily require a Qt commercial license, you can also do that with the open-source licensing options. As JIT is not compatible with App Store releases as of now, there are currently no plans to support it in our official SDK. We however can offer additional builds as part of our support hours program of course!
    3. Unfortunately there is also no general-purpose answer for that. We saw projects that highly benefitted from QtCC but also projects that did not prove any performance changes. Probably other developers might have more inout on that or you can also ask your question on the official Qt forums.
    4. Beside switching to the resource file for your QML files it is also a good practice to optimize any used resources (PNG optimization for file size, JPEG compression, audio bitrates, etc). Probably there are any further tips that other developers can share with you?


    Alex from Felgo


    Felgo Team
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