In order to make the forum more efficient and also our help faster, please consider the following advices:
Search before you post. It's very likely that it has been asked before and a solution has been found.
Don't rush to post a question when the problem first arises. Make sure you check your code properly, and have read the API docs (if applicable) or tested the API examples.
When you post, be clear with your problem and question. Writing things like ".. and then an error occurs. please help" doesn't really say much to people who want to help. If there is an error, what is the error message? The more details you can give, the faster you can get a good answer.
If possible, including relevant pieces of code can help to understand where the problem might be.
It's also good to include the version of your SDK, device/simulator you are targeting, and other relevant info.