Apple's IOS supports both synchronous and asynchronous tasks. In synchronous operations, tasks are performed one at a time. Therefore, other tasks must wait until the previous task is completed before continuing. Asynchronous tasks run simultaneously in the background. If background tasks are completed, you will be notified. Asynchronous programming ALLOWS you to process multiple requests at the same time, so you can accomplish more tasks in a shorter amount of time. 

The figure clearly indicates that synchronous tasks take more time to complete, i.e. 45 seconds since each task is performed one at a time. Asynchronous tasks, on the other hand, take less time to complete i.e. 20 seconds as they run simultaneously. 

Async work can be handled using third-party libraries. A few notable examples are Promises (PromiseKit), RxSwift, and ReactiveCocoa. 

Multibillions of Apple devices are in use worldwide. The number of iOS users worldwide has been rising steadily, which bodes well for iOS app developers. If you are seeking to make a career in iOS application development, then InterviewBit is the ideal platform to start with. In this article, we have put together 35+ of the most commonly asked iOS INTERVIEW questions to help you succeed at your iOS job interview. iOS developers also need to stay apprised of changes in the iOS community. Make sure you read Apple developer news, listen to PODCASTS and read blogs as well. This is likely not to be a question in an interview, but it makes you STAND out.   

Hopefully, these answers will be helpful in better understanding iOS basics, Swift, and advanced topics. Anyone looking to succeed in an iOS interview would benefit from knowing the answers to these Swift and iOS developer interview questions. Good luck with your interview! 

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