Checking available memory on iOS.

iOS_check_memory.c

#include <stdio.h>
#include <mach/mach.h>

natural_t mach_getTotalBytes() {
    static natural_t totalBytes=0;
    if (totalBytes>0) {
        return totalBytes;
    }   

    mach_port_t host_port;
    mach_msg_type_number_t host_vm_size;
    vm_size_t pagesize;

    host_port = mach_host_self();
    host_vm_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
    host_page_size(host_port, &pagesize);

    vm_statistics_data_t vm_stat = { 0 };

    kern_return_t kerr = host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_vm_size);

    if (kerr != KERN_SUCCESS) {   
        return 0;
    }   

    natural_t freeBytes = vm_stat.free_count * pagesize;
    natural_t wiredBytes = vm_stat.wire_count * pagesize;
    natural_t activeBytes = vm_stat.active_count * pagesize;
    natural_t inactiveBytes = vm_stat.inactive_count * pagesize;

    totalBytes = wiredBytes + freeBytes + activeBytes + inactiveBytes;

    printf("statistics free: %u wired: %u active: %u inactive: %u total: %u\n", freeBytes, wiredBytes, activeBytes, inactiveBytes, totalBytes);

    struct task_basic_info info;
    mach_msg_type_number_t size = sizeof(info);
    kern_return_t kerr2 = task_info(mach_task_self(),
                                 TASK_BASIC_INFO,
                                 (task_info_t)&info,
                                 &size);
    if (kerr2 == KERN_SUCCESS) {
        printf("statistics Memory in use (in bytes): %u virtual_size: %u\n", info.resident_size, info.virtual_size);
    }   
    return totalBytes;
}