// 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;}