IOS得到当前free memory size

墙外找到的，记一下以后可能有用

#import

#import

+(natural_t) 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 bytes */

    natural_t mem_free = vm_stat.free_count * pagesize;

    return mem_free;

}