Pass data from NSOperation to next NSOperation

Question

Is it possible to pass data from an NSOperation up the dependency chain to be used by the next NSOperation?

Thanks

Chris

Answer 1

Yes. The current NSOperation can access it's dependancies via the dependencies method:

NSArray *myDependancies = [self dependencies];

It can then access whatever properties you wish on the previous operations and pull out any data it requires.

In a recent project I found that I needed to pass data along so often that I created a subclass of NSOperation that automatically carried forward an NSDictionary of data from one operation to the next.

Answer 2

I've read the post where you can pass data between operations.

Also raywenderlich book Concurrency by Tutorials shows that you can pass data from dependecies like this:

let dependencyImage = dependencies
.compactMap { ($0 as? ImageDataProvider)?.image } .first