A little freeze on changing tab

[oolxg]

Hello everybody,

i've found some issue, makes my app freeze for a little

I have

TabView(selection: viewStore.binding(\.$pageIndex))  {
 ...
 }
.tabViewStyle(.page(indexDisplayMode: .never))

and when i change page(tab), my app freezes for a little.

Without selection or when i use @State as selection, there're no freezes or similar

Also when i do the following

TabView(selection: $selection) { ... }
    .tabViewStyle(.page(indexDisplayMode: .never))
     .onChange(of: selection) { let newValue in
        viewStore.send(.userChangedPage(newValue))
    }



...
case .userChangedPage(let newPageIndex):
    state.pageIndex = newPageIndex // 1
    return .none
...

i have the same freeze. What could be the reason for this and how could it be fixed?
(If in (1) i don't assign newPageIndex to state.pageIndex, there's no freeze)

[mbrandonw]

Can you show more code of what your view looks like, including how the viewStore is constructed?

[mbrandonw]

Ok, glad you figured it out.

In addition to that I will say that you are observing a lot of state that you aren't actually using. This will cause views to recompute more often than needed, and could slow things down.

For example, MangaReadingView and MangaReadingView could both do:

WithViewStore(self.store.stateless) { viewStore in 
  ...
}

...since both views don't actually read state. They only send actions.

And then other views that do need state could probably .scope the store to chisel the state down to something smaller.

But also, no need to do this until you really do see slow downs. Just a tip.

[oolxg]

Thank you for the tip, but the problem isn't solved completely

I need currentPage in MangaReadingView , but if i don't include it in static func ==(lhs: Self, rhs: Self), the view will not be updated (line 108-111)

[mbrandonw]

Is there a reason you are providing custom == implementations? It would be best to use the default synthesized conformance so that you can make sure all fields are being accounted for.

[oolxg]

It doesn't matter if i provide == or not - the lag remains

I mentioned == just to show, that if i don't compare pageIndex's, the lag disappears

[mbrandonw]

It's hard to know what is going on without code I can run myself, but I would suggest reducing the amount of state you are observing like I mentioned before. Many of your view stores can be stateless, and the others can probably be significantly reduced.