iOS跟踪可用和已用的内存

#import <mach/mach.h>
vm_size_t getUserMemory(){
    task_basic_info_data_t info;
    mach_msg_type_number_t size=sizeof(info);
    kern_return_t kerr=task_info(mach_task_self(), TASK_BASIC_INFO, (task_info_t)&info, &size);
    if (kerr==KERN_SUCCESS) {
        return info.resident_size;
    }
    return 0;
}
vm_size_t getFreeMemory() {
    mach_port_t host = mach_host_self();
    mach_msg_type_number_t size = sizeof(vm_statistics_data_t) / sizeof(integer_t); vm_size_t pagesize;
    vm_statistics_data_t vmstat;
    host_page_size(host, &pagesize);
    host_statistics(host, HOST_VM_INFO, (host_info_t) &vmstat, &size);
    return vmstat.free_count * pagesize;
}