The screening for iOS apps tends to be more difficult to pass compared to the competing platform. For this reason, it is often recommended to review the guidelines and avoid the common reasons for rejection before you make an iOS app.
These include inaccurate screenshots, misleading information, incomplete information, low perceived value, multiple bugs, broken links, unpolished content, offensive content, duplicate apps, frequent crashes, privacy issues, poor performance, hardware incompatibility, and bad user interface.
All of these have their solutions so don’t worry as long as you are following the rules and setting a high standard for your app. In case you do get rejected, study their comments and make the corresponding fixes before resubmitting for approval.
You might want to ask for help from experts if you get multiple rejections. They can show you exactly what went wrong and how you can make it better.