Objective-C frame, stack, buffer, heap

function has a frame where its local variables are stored. This memory is automatically allocated when a function starts and automatically deallocated when the function ends. In fact, local variables are sometimes called automatic variables because of this convenient behavior.

Sometimes, however, you need to claim a contiguous chunk of memory yourself – a buffer. Programmers often use the word buffer to mean a long line of bytes of memory. The buffer comes from a region of memory known as the heap, which is separate from the stack

  // Declare a pointer
    float *startOfBuffer;

    // Ask to use some bytes from the heap
    startOfBuffer = malloc(1000 * sizeof(float));

    // ...use the buffer here...

    // Relinquish your claim on the memory so it can be reused
    free(startOfBuffer);