iOS app crashing... only in non-debug mode

[kgregory]

My iOS app works fine when I launch it in debug mode and if I disconnect the USB cable, it continues to work fine. If I let the iPad sit idle for a while then I attempt to start the app, it will either crash immediately or sometimes it will run for a bit until I try to interact with it and then it will crash.

If I build it for release, then it crashes as soon as I interact with it. In the debug stream, it says "program received signal -111, thread:49c3f" followed by a bunch of hex codes. Then it says "hit maximum number of consecutive signals, stopping".

I find it odd that I'm getting debug messages in release mode... Is it supposed to do that?

Anyway, I'm not sure how to debug this. Any ideas?

[SGaist]

Hi,

One thing would be to first check if you have any un-initialiased variable. Then since you can make it crash after some idle time then you should try to get a backtrace. Don't disconnect the device.

You should also add some information:

• What version of Qt are you using ?
• What version of iOS ?
• What version of Xcode ?
• What version of macOS ?

[kgregory]

When you say initialised, do you mean like this?

//myclass.h
class myclass: public QObject
{
public:
    myclass();
    ~myclass();
    //other functions

private:
    int m_var1;
    int m_var2;
    //other variables
};

//myclass.cpp
myclass::myclass():
    m_var1(0), m_var2(0)   // <---- initialization?
{
   //some init code
}

I saw that in the example code I used as a starter but didn't really understand the point of it. For all of the member variables I created, I initialized them in the traditional c++ way within the body of the constructor (the "//some init code" part).

I'm using QT 5.9.2 and I think all of my other software is up-to-date with the latest release version.

[jsulm]

@kgregory The traditional way to initialise member variables in C++ is actually not in the body of the constructor, but like in your example:

myclass::myclass():
    m_var1(0), m_var2(0)
{}

[kgregory]

Hmm, I guess I was taught wrong.

What does the initialization look like if I have an array. For example, I initialize this array of 6 QColors in my object.

    //myclass declaration
    QColor colors[6];

    //myclass object constructor body
    colors[0] = QColor(255,0,0);
    colors[1] = QColor(255,255,0);
    colors[2] = QColor(0,255,0);
    colors[3] = QColor(0,255,255);
    colors[4] = QColor(0,0,255);
    colors[5] = QColor(255,0,255);

And what if the variable is another class like QDeviceDiscoveryAgent?

[SGaist]

Such complex initialisation goes in the body of the constructor.

As for a pointer to a object: in the list.

myclass::myclass():
    m_myAgent(new QDeviceDiscoverAgent)
{}

or

myclass::myclass():
    m_myAgent(new QDeviceDiscoverAgent(this))
{}

if you want to pass it one or more parameters.