What is the difference between NSInvocationOperation and NSBlockOperation

Question

There are three operation classes in Foundation Framework(NSOperation, NSInvocationOperation and NSBlockOperation).

I already

Answer 1

As par Apple doc NSInvocationOperation and NSBlockOperation Both are subclass of NSOperation

NSInvocationOperation Class

The NSInvocationOperation class is a concrete subclass of NSOperation that manages the execution of a single encapsulated task specified as an invocation. You can use this class to initiate an operation that consists of invoking a selector on a specified object. This class implements a non-concurrent operation

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NSBlockOperation Class

The NSBlockOperation class is a concrete subclass of NSOperation that manages the concurrent execution of one or more blocks. You can use this object to execute several blocks at once without having to create separate operation objects for each. When executing more than one block, the operation itself is considered finished only when all blocks have finished executing.

Blocks added to a block operation are dispatched with default priority to an appropriate work queue. The blocks themselves should not make any assumptions about the configuration of their execution environment.