The challenge code compiles but the playground crashes unless the import line above is added to the RxSwiftPlayground.playground file.
(A few minutes later)
Curiously, if I remove the import statement the playground continues to work.
So far, having reached chapter 7, I seem to be spending as much getting the examples to compile and run as I do actually using them. I hope this isn’t true of RxSwift in general.
No, everything is working now. Before I open any project that uses the playground, I edit the podfile and include the extra lines that are given towards the end of the answers to this question: Playground does not execute on first chapter - #28 by hhschulz
After that, I run ‘pod install’ and ‘pod update’ (and then run them both a second time). After that, the project usually run OK. The playground still stops from time to time, particularly if it tries to run the code while you are typing it in. When that happens, I stop and start Xcode and that usually fixes things.
I think Xcode playgrounds are still much too fragile to use in tutorials.