First off, there is nothing "rude" about downvotes. Voting is a big and important part of how this site works, and it is important to point out that there is no such thing as "wrong" downvotes. People are free to downvote posts for whatever reasons they like. They're also under no obligation to explain to you why they've chosen to cast a downvote. Anonymity is guaranteed. If you don't like this system, you're free to go elsewhere.
But let's look at some of the specific examples you cite. You say your answer to an Objective C question was downvoted, "which Was totally ridiculous". I disagree. In that case, people even left comments explaining why they thought your answer was wrong or misleading. I personally don't know anything about Objective C, so I can't actually comment on whether those people are right or wrong, but it appears to me that
@autoreleaspool are important language keywords and something worth knowing about. Including them is not wrong or a mistake as your answer suggests.
The other thing I can tell, even without having much knowledge of Objective C, is that your answer isn't particularly helpful in answering the question. You haven't formatted code samples appropriately, so they are difficult to read. You also haven't used the correct markdown syntax to create a numbered list, so that looks sloppy and difficult to read as well. You also don't explain what is wrong with the code, or why these mistakes are causing errors. You just propose an alternative way of writing it. That's great if people want to just copy and paste code off of the Internet, but real developers don't do that. They try to figure out what caused their mistakes, why they're causing the problems they see, and how to fix them in the future. Your answer doesn't really help anyone do that.
You say that "I also answered few questions and got plus points, which means I am notspamming Here.." To my knowledge, no one has accused you of spamming. Downvotes do not indicate spam; we have spam flags for that, and spam answers are automatically deleted from the site. Yes, you provided an answer that appears to be helpful to this question. Good for you. You got 2 upvotes for it. That doesn't prove anything about the quality of the rest of your contributions.
Downvotes are not cast against users, they're applied against individual posts. Proving that some of your contributions have been good or helpful is not a reason that others of your contributions should not be downvoted.
Is this your Approach to treat NOOBS on S.O.?? If this behavior continues soon your site will lose Reputation. I am greatly disappointed by your people's behavior. Hope you will understand my problem and treat my question positively..
Yes. If "NOOBS" give answers that are incorrect or misleading, those answers will and should be downvoted. Again, that's how the site works. Voting is in large part intended to provide a mechanism of assessing the technical merit of responses. If you don't know the answer and can't help, then you probably shouldn't post an answer to that question. If you do, you indeed run the risk of being downvoted.
And yes, downvotes do cost you reputation. But only a few points. You lose 2 points for having an answer downvoted, but you gain 10 points for having an answer upvoted. A few upvotes more than make up for a couple of downvotes.
None of this is to say that "NOOBS" are unwelcome here. But whining about downvotes is quite unwelcome. The other thing that's unwelcome are "plz-give-me-teh-codez" questions. This is not that kind of a site. Questions that include phrases like "Anyone Knows code for that??" are quite likely to be downvoted and closed. Consider yourself warned.
For tips on how to ask questions (and avoid the eventual fate of perpetually low-quality contributors), look here: What can I do when getting "We are no longer accepting questions/answers from this account"?