Check if my iOS App is running under the debugger

Includes

#include <assert.h>
#include <stdbool.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/sysctl.h>

Returns true if the current process is being debugged (either running under the debugger or has a debugger attached post facto).

static bool AmIBeingDebugged(void) {
    int                 junk;
    int                 mib[4];
    struct kinfo_proc   info;
    size_t              size;
    info.kp_proc.p_flag = 0;
    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_PID;
    mib[3] = getpid();
    size = sizeof(info);
    junk = sysctl(mib, sizeof(mib) / sizeof(*mib), &info, &size, NULL, 0);
    assert(junk == 0);
    return ( (info.kp_proc.p_flag & P_TRACED) != 0 );
}

Via Apple Technical Q&A (More info here)