[iOS] NSOperation vs. GCD

GCD is a low-level C-based API.
NSOperation and NSOperationQueue are Objective-C classes.
NSOperationQueue is objective C wrapper over GCD. If you are using NSOperation, then you are implicitly using Grand Central Dispatch.

 

GCD advantage over NSOperation:

1. implementation
   For GCD implementation is very light-weight
   NSOperationQueue is complex and heavy-weight

NSOperation advantages over GCD:

1. Control On Operation
   you can Pause, Cancel, Resume an NSOperation
2. Dependencies
   you can set up a dependency between two NSOperations operation will not started until all of its dependencies return true for finished.
3. State of Operation
   can monitor the state of an operation or operation queue. ready ,executing or finished
4. Max Number of Operation
   you can specify the maximum number of queued operations that can run simultaneously

When to Go for GCD or NSOperation

when you want more control over queue (all above mentioned) use NSOperation and for simple cases where you want less overhead (you just want to do some work "into the background" with very little additional work) use GCD

 

 

 

 

 

Ref. 

https://stackoverflow.com/questions/10373331/nsoperation-vs-grand-central-dispatch