How to cache data between view updates with willChange instead of didChange?

Question

Created Jul ’19

Replies 2

Boosts 0

Participants 2

I have view A that displays data requiring some heavy computation.

Instead of redoing the computation over and over again, the data is cached every time some piece of data is modified by view B. This worked fine in beta 3, because changes triggered by view B would cause the data to:

catch the didSet message
update the cache
send the didChange message
view A (and B) was updated as a result

How can I to this in beta 4, now that willSet is used instead and it's too early to update the cache?

Answered by caram in 372881022

It turns out the solution was fairly simple:

catch the willSet message
set the cache to nil (i.e. defer update to when the view will be refreshed)
send the willChange message
the views A and B will be updated and this will repopulate the cache

Boost

Answer 1

SpaceMan OP

Jul ’19

Put the willChange.send() message in didSet? That is what I am doing now, but I will change it in my code.

0

Answer 2

caram OP

Jul ’19

Accepted Answer

It turns out the solution was fairly simple:

catch the willSet message
set the cache to nil (i.e. defer update to when the view will be refreshed)
send the willChange message
the views A and B will be updated and this will repopulate the cache

0