can't save the CoreData by call saveandwait function

[chengelvis]

hi,
when I call the "saveandwait" function, I found I could not save the data to CoreData, only can save data in main queue context.
I call the "saveandwait" function just for save and don't write/read data in the parameter block.
can you tell me why?
@AugustRush @gabrielPeart