// 获取当前设备可用内存及所占内存的头文件

#import <sys/sysctl.h>

#import <mach/mach.h>

// 获取当前设备可用内存(单位：MB）

- (double)availableMemory

{

  vm_statistics_data_t vmStats;

  mach_msg_type_number_t infoCount = HOST_VM_INFO_COUNT;

  kern_return_t kernReturn = host_statistics(mach_host_self(), 

                                             HOST_VM_INFO, 

                                             (host_info_t)&vmStats, 

                                             &infoCount);

  if (kernReturn != KERN_SUCCESS) {

    return NSNotFound;

  }

  return ((vm_page_size *vmStats.free_count) / 1024.0) / 1024.0;

}

// 获取当前任务所占用的内存（单位：MB）

- (double)usedMemory

{

  task_basic_info_data_t taskInfo;

  mach_msg_type_number_t infoCount = TASK_BASIC_INFO_COUNT;

  kern_return_t kernReturn = task_info(mach_task_self(), 

                                       TASK_BASIC_INFO, 

                                       (task_info_t)&taskInfo, 

                                       &infoCount);

  if (kernReturn != KERN_SUCCESS

      ) {

    return NSNotFound;

  }

  return taskInfo.resident_size / 1024.0 / 1024.0;

}