Log iOS app memory usage

void logMemoryUsage(void)
{
    static natural_t initialUsed = 0xFFFFFFFF;
    static natural_t previousUsed = 0xFFFFFFFF;

    mach_port_t host_port = mach_host_self();
    mach_msg_type_number_t host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
    vm_size_t pagesize;
    vm_statistics_data_t vm_stat;

    host_page_size(host_port, &pagesize);

    if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS)
    {
        NSLog(@"Failed to fetch vm statistics");
    }

    natural_t memUsed = (vm_stat.active_count + vm_stat.inactive_count + vm_stat.wire_count) * pagesize;
    natural_t memFree = vm_stat.free_count * pagesize;
    natural_t memTotal = memUsed + memFree;

    if (initialUsed == 0xFFFFFFFF)
    {
        initialUsed = memUsed;
    }
    if (previousUsed == 0xFFFFFFFF)
    {
        previousUsed = memUsed;
    }
    NSLog(@"Memory usage (KB): app %d, delta %d, used %u/%u",
          ((int)memUsed - (int)initialUsed) / 1024,
          ((int)memUsed - (int)previousUsed) / 1024,
          memUsed / 1024,
          memTotal / 1024);
    previousUsed = memUsed;
}