What is Concurrency?

• Doing multiple things at the same time.
• Taking advantage of number of cores available in multicore CPUs.
• Running multiple programs in parallel.

Objectives of Concurrency

• Running program in background without hogging CPU.
• Define Tasks, Define Rules and let the system take the responsibility of performing them.
• Improve responsiveness by ensuring that the main thread is free to respond to user events.

DISPATCH QUEUES

Grand central dispatch – dispatch queues allows us to execute arbitrary blocks of code either asynchronously or synchronously All Dispatch Queues are first in – first out All the tasks added to dispatch queue are started in the order they were added to the dispatch queue.