Tell about block and GCD

Answer Posted / babu

Block: Block objects are a C-level syntactic and runtime feature. Blocks are particularly useful as a callback because the block carries both the code to be executed on callback (on completion handler block) and the data needed during that execution.

GCD: GCD (Grand Central Dispatch) provides and manages FIFO queues to which your application can submit tasks in the form of block objects. Blocks submitted to dispatch queues are executed on a set of threads completely managed by the system. No guarantee is made as to the thread on which a task executes. GCD allows three kinds of queues:

Main: tasks execute serially on your application’s main thread

Concurrent: tasks are dequeued in FIFO order, but run concurrently and can finish in any order.

Serial: tasks execute one at a time in FIFO order

Is This Answer Correct ?    0 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

What is the responder chain?

455


How could you setup live rendering ?

506


How do you usually persist data on ios? : IOS Architect

454


What is nsoperation and nsoperationqueue?

443


What is App Bundle in iOS operating system?

509






What is iphone screen size?

489


what is the difference between bounds and frame?

466


When a nsfetchrequest fetches an entity object from store, does it fetch all of its data at once?

457


What are the different store migration options? When are they used? How do they work? What is mapping model?

377


Differentiate between release and pool drain?

476


Can I have relationship between entities in separate stores (in case of configurations)?

453


What coding language is used for ios apps?

429


What is the use of 'dynamic' keyword?

477


Define autorealease pool?

482


Explain the difference between bounds and frame?

402