The iPhone has limited memory,and as developer its our responsibility to manage memory optimally. On one hand caching improves performance while on other hand it uses ‘expensive’ memory, and we must optimally balance between both sides.

Once you received memory warning you can release unwanted objects to free up the memory, but knowing how much memory is available OR free on iPhone will help you make calculated decisions before low memory warning is even triggered. OR simply you can ask user to restart the iPhone and then launch the application.This Tip will help you calculate Available Memory for your application.

So, here is code to calculate available memory :

#import 
#import 
 
static void print_free_memory () {
    mach_port_t host_port;
    mach_msg_type_number_t host_size;
    vm_size_t pagesize;
 
    host_port = mach_host_self();
    host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
    host_page_size(host_port, &pagesize);        
 
    vm_statistics_data_t vm_stat;
 
    if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS)
        NSLog(@"Failed to fetch vm statistics");
 
    /* Stats in bytes */
    natural_t mem_used = (vm_stat.active_count +
                          vm_stat.inactive_count +
                          vm_stat.wire_count) * pagesize;
    natural_t mem_free = vm_stat.free_count * pagesize;
    natural_t mem_total = mem_used + mem_free;
    NSLog(@"used: %u free: %u total: %u", mem_used, mem_free, mem_total);
}

Happy Coding :)

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