What are blocks in iOS?

Related questions

1. What is Singleton design pattern in iOS?
2. What is thread in iOS?
3. What is block Swift?
4. What is the difference between GCD and NSOperationQueue in iOS?
5. What is optional chaining in Swift?
6. What is race condition in Swift?
7. What is the use of dispatch queue in iOS?
8. What does __ block do?
9. What is the difference between asynchronous and synchronous programming?
10. What is completionHandler?

Tags

1. #functions
2. #since
3. #executed
4. #class
5. #methods
6. #first
7. #which
8. #block
9. #objects
10. #returned
11. #chunk
12. #future
13. #parameters
14. #variables
15. #saying
16. #assigned
17. #passed
18. #blocks
19. #objective
20. #regular
21. #fancy