Free memory on iOS

gistfile1.m

-(float) get_free_memory {
  mach_port_t host_port;
  mach_msg_type_number_t host_size;
  vm_size_t pagesize;
  host_port = mach_host_self();
  host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
  host_page_size(host_port, &pagesize);
  vm_statistics_data_t vm_stat;
  
  if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS) {
    NSLog(@"Failed to fetch vm statistics");
    return 0;
  }
  
  /* Stats in megabytes */
  natural_t mem_free = vm_stat.free_count * pagesize;
  return mem_free / (float)(1024*1024);
}