移动设备内存较小，开发期间，很容易导致设备出现内存警告，这个时候打印出内存信息可以帮助我们了解内存情况
1，可用内存
float AppDelegate::availableMemory()
{
mach_msg_type_number_t infoCount = HOST_VM_INFO_COUNT;
vm_statistics_data_t vmStats;
kern_return_t kernReturn = host_statistics(mach_host_self(), HOST_VM_INFO, (host_info_t)&vmStats,
&infoCount);
if(kernReturn != KERN_SUCCESS)
{
return 0;
}
return ((vm_page_size * vmStats.free_count) / 1024.0) / 1024.0;
}
2. app占用内存，可以在内存警告发生时打印该数据
float AppDelegate::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 0;
}
return taskInfo.resident_size / 1024.0 / 1024.0;
}