在实际设备上发生SIGSEGV错误，但在iOS模拟器上未发生

Question

I am the developer of a cydia tweak named CountdownCenter. I was trying to create a digital clock appearance for my widget, so I created a sample app that does this perfectly. After doing this, I transferred this data into the code of my tweak but, this causes a SIGSEGV crash on my iPhone. After some testing, I found the part that is responsible for the crash, but I just can't find what's wrong as this part would work on a normal app. Can you help me please?

Here is the code:

int digitarray[10];
    int c = 0;
    digitarray[0] = 0;
    digitarray[1] = 0;
    while (secon>0) {
        int digitt = secon % 10;
        digitarray[c] = digitt;
        secon /= 10;
        c++;
    }
        lbl.text = [NSString stringWithFormat:@"%d", digitarray[0]];
          [self selectimage:digitarray[0] img:numview10];

Answer 1

SIGSEGV usually means, that you're trying to access memory, that you are not allowed to access. (btw are you testing this with a release build?) Maybe fe here (there are some other similar places too):

c = 0;
while (secon>0) {
    int digitt = secon % 10;
    digitarray[c] = digitt;
    secon /= 10;
    c++;
}

There are some possibilities:

• secon (horrible variable names btw...) is a float or double , in that case the while loop is either never entered or never left
• c becomes so large that it's beyond digitarray 's bounds

To solve this issue I would recommend to but a breakpoint at the beginning of your code and check it step by step.