What if I don’t understand the very first 2 chapters fully, should I read it thousands of times to get it? or should I keep going to the next chapters?
You don’t need to read it thousands of times. Try to determine what the stumbling blocks are before moving on. It is most likely that you will need to get a better grasp of some basic concepts.
When I get stuck I usually will reference another source such as the Apple Developer documentation for another point of view. Then I would re-read the first chapter then start a new project and try again. I did this several times before I was able to move past chapter 4. Due to my work schedule I had to stop at Chapter 8. I’m re-starting at Chapter 1 today!