App crash at _CTServerConnectionCellMonitorGetCellInfo

Question

Hi I am using the code of valexa and app getting crash while getting signal strenght at

this line

if (!mach_port || !conn) return;

int count = 0;
_CTServerConnectionCellMonitorGetCellCount(mach_port, conn, &count);

if (count > 0) {
    int i;
    for (i = 0; i < count; i++) 
    {
        CellInfoRef cellinfo;

        _CTServerConnectionCellMonitorGetCellInfo(mach_port, conn, i, &cellinfo);

i have taken code from here

https://github.com/valexa/VAFieldTest