[ios] Hide the Export all bookmarks and tracks button when there are no bookmarks

[kirylkaveryn]

Results:

[biodranik]

Дзякуй!

[biodranik]

Why the order here is important?

[kirylkaveryn]

When the manager.deleteCategory(category.categoryId) is called the bookmarks manager will trigger the observers that they should update their content. And the

func onBookmarksCategoryDeleted(_ groupId: MWMMarkGroupID) {
    reloadData()
  }

will trigger the reloading of the table (and remove the row).
BUT
view?.delete(at: [IndexPath(row: index, section: section)]) also removes he row.

And if manager.deleteCategory(category.categoryId) is called first (and reloads the data), the view?.delete(at: [IndexPath(row: index, section: section)]) will attempt to delete the element that is already deleted ant it crashes the app.

So it is important to reorder this lines to update the local data source in categories.remove(at: index), and only after that update the core.

[biodranik]

Question: is view?.delete(at: [IndexPath(row: index, section: section)]) call needed in this case?

[kirylkaveryn]

Its needed for the deletion animation with swipe instead of just reloading with fade.

[biodranik]

A simpler, faster version without any side effects may be better than some animation, no? )

[kirylkaveryn]

Looks a little bit rough...

@biodranik WDYT?

[biodranik]

No big difference, ok, let's use it as is.

[biodranik]

LGTM, дзякуй!

[biodranik]

A simpler, faster version without any side effects may be better than some animation, no? )