Swift stack and heap understanding

IosSwiftMemoryHeap MemoryStack Memory

Ios Problem Overview


I want to understand what is stored in the stack and heap in swift. I have a rough estimation: Everything that you print and the memory address appears not the values, those are stored in the stack, and what is printed out as values, those are on the heap, basically according to value and reference types. Am I completely wrong? And optionally, could you provide a visual representation of the stack/heap?

Ios Solutions


Solution 1 - Ios

As @Juul stated Reference types are stored in the Heap and values in the stack.

Here is the explanation:

Stack and Heap

Stack is used for static memory allocation and Heap for dynamic memory allocation, both stored in the computer's RAM .

Variables allocated on the stack are stored directly to the memory, and access to this memory is very fast, and its allocation is determined when the program is compiled. When a function or a method calls another function which in turns calls another function, etc., the execution of all those functions remains suspended until the very last function returns its value. The stack is always reserved in a LIFO order, the most recently reserved block is always the next block to be freed. This makes it really simple to keep track of the stack. Freeing a block from the stack is nothing more than adjusting one pointer.

enter image description here

Variables allocated on the heap have their memory allocated at run time, and accessing this memory is a bit slower, but the heap size is only limited by the size of virtual memory. Elements of the heap have no dependencies with each other and can always be accessed randomly at any time. You can allocate a block at any time and free it at any time. This makes it more complex to keep track of which parts of the heap are allocated or free at any given time.

For Escaping Closure:
An important note to keep in mind is that in cases where a value stored on a stack is captured in a closure, that value will be copied to the heap so that it's still available by the time the closure is executed.

For more reference: http://net-informations.com/faq/net/stack-heap.htm

Solution 2 - Ios

Classes (reference types) are allocated in the heap, value types (like Struct, String, Int, Bool, etc) live in the stack. See this topic for more detailed answers: https://stackoverflow.com/questions/24232799/why-choose-struct-over-class/24232845

Solution 3 - Ios

Stack vs Heap

Stack is a part of thread. It consists of method(function) frames in LIFO order. Method frame contains local variables. Actually it is method stack trace which you see during debugging or analysing error[About]. New copy of value is created - it can be a copy of reference type address or copy of value type(Copy on Write mechanism). Thread safe[About]

Heap another part of memory where ARC[About] come in play. It takes more time to allocate memory here(find appropriate place and allocate it in synchronous way). New copy of reference is created

Theses concepts are the same as [JVM illustration]

Xcode propose you next variant using Debug Memory Graph

enter image description here *To see Backtrace use Malloc Stack Logging

[Value vs Reference type]
[Class vs Struct]

Attributions

All content for this solution is sourced from the original question on Stackoverflow.

The content on this page is licensed under the Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionDániel NagyView Question on Stackoverflow
Solution 1 - IosJaydeep VyasView Answer on Stackoverflow
Solution 2 - IosJuulView Answer on Stackoverflow
Solution 3 - IosyoAlex5View Answer on Stackoverflow