Detect if iOS app is being debugged/instrumented

isBeingDebugged.m

// attempt 1
static BOOL isBeingDebugged()
{
    static BOOL cachedValue = NO;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        char buffer[2*MAXCOMLEN + 1];
        int len = proc_name(getppid(), buffer, 2*MAXCOMLEN);
        buffer[len] = 0;
        cachedValue = !strncmp(buffer, "debugserver", len);
    });
    return cachedValue;
}

// attempt 2
#import <unistd.h>
#include <sys/sysctl.h>

extern int proc_name(int pid, void * buffer, uint32_t buffersize);
static BOOL isBeingDebugged()
{
    static BOOL cachedValue = NO;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        struct kinfo_proc info = {
            .kp_proc.p_flag = 0
        };
        size_t size = sizeof(info);
        if (!sysctl((int[]){CTL_KERN, KERN_PROC, KERN_PROC_PID, getpid()}, 4, &info, &size, 0, 0))
        {
            cachedValue = !!(info.kp_proc.p_flag & P_TRACED);
        }
    });
    return cachedValue;
}