With the increasing use of mobile applications, everyone is drawn to make an application and publish it online in the App store. People use various marketing channels from SMM to using services like https://app-promotion.net/buy-app-store-reviews/. However, before you endeavor to develop an iOS app, you should know that all apps submitted to the app store go through a strict review process.

Reading and following the guidelines provided by Apple while developing mobile applications will save a lot of time for developers and other team members, as well as reviewers.

Apple is very picky about apps and has a well-established process for reviewing every app submitted to its store. Recommend going through the review process once.

The most common reasons for rejection of applications submitted to the App store are highlighted below:
# 1 Insufficient information
Apple's biggest rejection is due to incomplete or faulty information.

You are advised to fill in all the required information, provide an elaborate list of the application features along with any necessary procedures to run it.

Provide any and all data necessary to review the information, for example, if some functions like my account, my orders require you to register, provide a valid username and password for the demonstration

A demo video of the application may also suffice for the purpose.

# 2 Failures and errors
Apple does not expect crashes or errors when reviewing the application to submit it only when it has been thoroughly tested on all devices and all errors have been fixed.

Any buggy app will hamper the review process, and in turn, attract rejection.

So instead of resubmitting it after you've tried it, it's better to invest time beforehand.

# 3 Personal privacy of users
When it comes to user privacy, Apple considers it the most important factor.

If your application is going to use the user's private data from their device, then you are asked to inform the client through the Privacy Policy and take consent.

In any case, the violation of the privacy policy will be a reason to reject your application.

# 4 Violation of Apple guidelines
Apple has published clear guidelines for app design, app content, as well as review, therefore the user needs to adhere to them, and violating them will certainly invite rejection.

Although some rules are common sense, others are worth reading as they fall into the technical or design department.

# 5 No repeated apps
All applications developed for the iTunes application store must comply with all terms and conditions specified in the guidelines of trademarks and copyrights of Apple and the list of brands Apple.

If you plan to get the benefit by replicating the most popular app or remodeling the latest app, be careful and steer clear.

Only unique ideas are expected and accepted.
# 6 Advertisements
Clearly, indicate whether your application uses advertising or not. If yes, please use the Advertising Identifier (IDFA) to serve the advertising and test it thoroughly on iOS devices.

If not, you should not show any ad, otherwise, it will surely be rejected and marked as invalid.

# 7 User interface
Apple has set a high standard for the user interface by requiring you to be simple, refined, and easily accessible.

Make sure the navigation is as clear as possible and the functions as intuitive as they seem.

The user interface must meet the requirements set by Apple by planning your design carefully and following their design guides and the dos and don'ts of user interface design.

Conclusion:
Apple's panel is very sensible to check everything before rejecting/accepting your application. They strictly follow the guidelines and do not compromise on quality.

There could be more reasons, in addition to what we have outlined above, for the rejection of the iOS app, however, the main focus is on the usability of the app as well as the uniqueness of the content.