UISearchDisplayController animate reloadData

Question

I\'ve been reading all the documentation about UISearchDisplayController and its delegate but I can\'t find any way to animate the table view when

Answer 1

I know this question is old, but I recently faced this and wanted a solution that would work regardless of how the NSFetchedResultsController was initialized. It's based on @martin-r's answer above.

Here's the corresponding gist: https://gist.github.com/stephanecopin/4ad7ed723f9857d96a777d0e7b45d676

import CoreData

extension NSFetchedResultsController {
    var predicate: NSPredicate? {
        get {
            return self.fetchRequest.predicate
        }
        set {
            try! self.setPredicate(newValue)
        }
    }

    var sortDescriptors: [NSSortDescriptor]? {
        get {
            return self.fetchRequest.sortDescriptors
        }
        set {
            try! self.setSortDescriptors(newValue)
        }
    }

    func setPredicate(predicate: NSPredicate?) throws {
        try self.setPredicate(predicate, sortDescriptors: self.sortDescriptors)
    }

    func setSortDescriptors(sortDescriptors: [NSSortDescriptor]?) throws {
        try self.setPredicate(self.predicate, sortDescriptors: sortDescriptors)
    }

    func setPredicate(predicate: NSPredicate?, sortDescriptors: [NSSortDescriptor]?) throws {
        func updateProperties() throws {
            if let cacheName = cacheName {
                NSFetchedResultsController.deleteCacheWithName(cacheName)
            }

            self.fetchRequest.predicate = predicate
            self.fetchRequest.sortDescriptors = sortDescriptors
            try self.performFetch()
        }

        guard let delegate = self.delegate else {
            try updateProperties()
            return
        }

        let previousSections = self.sections ?? []
        let previousSectionsCount = previousSections.count
        var previousObjects = Set(self.fetchedObjects as? [NSManagedObject] ?? [])
        var previousIndexPaths: [NSManagedObject: NSIndexPath] = [:]
        previousObjects.forEach {
            previousIndexPaths[$0] = self.indexPathForObject($0)
        }
        try updateProperties()
        let newSections = self.sections ?? []
        let newSectionsCount = newSections.count
        var newObjects = Set(self.fetchedObjects as? [NSManagedObject] ?? [])
        var newIndexPaths: [NSManagedObject: NSIndexPath] = [:]
        newObjects.forEach {
            newIndexPaths[$0] = self.indexPathForObject($0)
        }

        let updatedObjects = newObjects.intersect(previousObjects)
        previousObjects.subtractInPlace(updatedObjects)
        newObjects.subtractInPlace(updatedObjects)

        var moves: [(object: NSManagedObject, fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath)] = []
        updatedObjects.forEach { updatedObject in
            if let previousIndexPath = previousIndexPaths[updatedObject],
                let newIndexPath = newIndexPaths[updatedObject]
            {
                if previousIndexPath != newIndexPath {
                    moves.append((updatedObject, previousIndexPath, newIndexPath))
                }
            }
        }

        if moves.isEmpty && previousObjects.isEmpty && newObjects.isEmpty {
            // Nothing really changed
            return
        }

        delegate.controllerWillChangeContent?(self)

        moves.forEach {
            delegate.controller?(self, didChangeObject: $0.object, atIndexPath: $0.fromIndexPath, forChangeType: .Move, newIndexPath: $0.toIndexPath)
        }

        let sectionDifference = newSectionsCount - previousSectionsCount
        if sectionDifference < 0 {
            (newSectionsCount.. 0 {
            (previousSectionsCount..

It exposes 2 properties on the NSFetchedResultsController, predicate and sortDescriptors which mirrors those found in the fetchRequest.
When either of these properties are set, the controller will automatically compute changes the changes and send them through the delegate, so hopefully there is no major code changes. If you don't want animations, you can still directly set predicate or sortDescriptors on the fetchRequest itself.