iOS avalilable memory

printFreeMemory.m

- (void)printFreeMemory
{    
    return;
    
    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;
    }
    
    natural_t mem_used = (vm_stat.active_count +
                          vm_stat.inactive_count +
                          vm_stat.wire_count) * pagesize;
    natural_t mem_free = vm_stat.free_count * pagesize;
    natural_t mem_total = mem_used + mem_free;
    
    NSLog(@"used: %f free: %f total: %f", mem_used / 1024.0 / 1024.0, mem_free / 1024.0 / 1024.0, mem_total/ 1024.0/ 1024.0);
}

You may replace sizeof(vm_statistics_data_t) / sizeof(integer_t) with HOST_VM_INFO_COUNT