Question

What ways are there to deal with memory issues on the iPhone?

Is it possible to ask how much memory is available before jumping into a memory intensive section of code?

(or perhaps Apple would just say that if you have to use so much memory you are on the wrong platform?)

Answer 1

UIApplicationDelegate’s applicationDidReceiveMemoryWarning: will let you know if you’re using too much memory. If you want to check before a memory intensive operation, here’s a function that gets the available free memory in bytes on iOS:

natural_t  TSGetFreeSystemMemory(void) {
    mach_port_t           host_port = mach_host_self();
    mach_msg_type_number_t   host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
    vm_size_t               pagesize;
    vm_statistics_data_t     vm_stat;

    host_page_size(host_port, &pagesize);

    if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS) 
        printf("failed to get host statistics");;

    // 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;

    return mem_free;
}