Question

我是iOS开发的新手，我是第二个使用Swift的应用程序。我无法合并SearchBar＆amp;在我的表视图控制器中显示搜索。

我的应用中有2个观看次数。 First View生成一个水果阵列。第一视图的输出：[Apple，Orange，Banana，Pears]。然后[石榴，梨，西瓜，甜瓜]等。一次一个阵列。

每个水果数组都使用NSFetchedResultsController存储在核心数据中，以显示在tableviewcontroller中。我的Coredata布局：

import UIKit
import CoreData

@objc(Fruits)

class Fruits: NSManagedObject {
    @NSManaged var date: String
    @NSManaged var fruit: String
}

我的第二个视图显示水果列表。现在我添加了一个搜索栏＆amp;在表格视图的顶部显示。但我无法使其发挥作用。

使用的协议：

class HistoryTableViewController: UITableViewController, NSFetchedResultsControllerDelegate{

声明的变量：

let managedObjectContext: NSManagedObjectContext? = (UIApplication.sharedApplication().delegate as? AppDelegate)?.managedObjectContext
var fetchedResultsController: NSFetchedResultsController?
var fetchRequest = NSFetchRequest(entityName: "Fruits")

我班上有两个出路：

@IBOutlet weak var searchBar: UISearchBar! // the Search Bar & Display
@IBOutlet var tblHistory: UITableView! = nil // Table View

表格视图的数据填充：

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return fetchedResultsController?.sections?.count ?? 0
    }
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
    {   
        return fetchedResultsController?.sections?[section].numberOfObjects ?? 0
    }

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: (NSIndexPath!)) -> UITableViewCell
    {
        let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as UITableViewCell
            if let cellFruit = fetchedResultsController?.objectAtIndexPath(indexPath) as? Fruits
            {
                cell.textLabel?.text = cellFruit.fruit
                cell.detailTextLabel?.text = cellFruit.date
            }
            return cell
    }

    // Override to support conditional editing of the table view.
override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
        // Return false if you do not want the specified item to be editable.
        return true
    }

    //MARK: NSFetchedResultsController Delegate Functions
func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {

        switch type {
        case NSFetchedResultsChangeType.Insert:
            tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: UITableViewRowAnimation.Fade)
            break
        case NSFetchedResultsChangeType.Delete:
            tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: UITableViewRowAnimation.Fade)
            break
        case NSFetchedResultsChangeType.Move:
            break
        case NSFetchedResultsChangeType.Update:
            break
        default:
            break
        }
    }

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
            //Delete object from entity, remove from list
            if editingStyle == .Delete {
            }
            switch editingStyle {
            case .Delete:
managedObjectContext?.deleteObject(fetchedResultsController?.objectAtIndexPath(indexPath) as! Fruits)
                do {
                    try managedObjectContext?.save()
                }catch{}
                print("Fruit set deleted successfully.")
            case .Insert:
                break
            case .None:
                break
            }
        }
func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {

        switch type {
        case NSFetchedResultsChangeType.Insert:
            tableView.insertRowsAtIndexPaths(NSArray(object: newIndexPath!) as! [NSIndexPath], withRowAnimation: UITableViewRowAnimation.Fade)
            break
        case NSFetchedResultsChangeType.Delete:
            tableView.deleteRowsAtIndexPaths(NSArray(object: indexPath!) as! [NSIndexPath], withRowAnimation: UITableViewRowAnimation.Fade)
            break
        case NSFetchedResultsChangeType.Move:
            tableView.deleteRowsAtIndexPaths(NSArray(object: indexPath!) as! [NSIndexPath], withRowAnimation: UITableViewRowAnimation.Fade)
            tableView.insertRowsAtIndexPaths(NSArray(object: newIndexPath!) as! [NSIndexPath], withRowAnimation: UITableViewRowAnimation.Fade)
            break
        case NSFetchedResultsChangeType.Update:
            tableView.cellForRowAtIndexPath(indexPath!)
            break
        default:
            break
        }
    }

    func controllerWillChangeContent(controller: NSFetchedResultsController) {
        tableView.beginUpdates()
    }

    func controllerDidChangeContent(controller: NSFetchedResultsController) {
        tableView.endUpdates()
    }

如何从coredata搜索任何水果并过滤视图？应该将哪个代理功能用于搜索栏＆amp;在Swift编码中显示功能？

对于我可能在这里错过的概念的任何帮助将不胜感激！感谢。

更新：，因为Daniel Eggert建议我尝试将谓词用于搜索控制器功能，但Predicate总是提供 nil 。我错过了什么？

在类中声明的变量：

var results: NSArray = []
var searchPredicate: NSPredicate?
var searchController: UISearchController!

谓词函数：

//Search Functionality
        func updateSearchResultsForSearchController(searchController: UISearchController)
        {
            let searchText = self.searchController?.searchBar.text
            if let searchText = searchText {
                searchPredicate = NSPredicate(format: "fruit contains[cd] %@", searchText)
                results = (self.fetchedResultsController!.fetchedObjects?.filter() {
                    return self.searchPredicate!.evaluateWithObject($0)
                    } as! [Fruits]?)!
            self.tableView.reloadData()
            }
        }

    // Called when text changes (including clear)
    func searchBar(searchBar: UISearchBar, textDidChange searchText: String)
    {
        if !searchText.isEmpty
        {
            var predicate: NSPredicate = NSPredicate()
            predicate = NSPredicate(format: "fruit contains [cd] %@", searchText)
            let sortDescriptor = NSSortDescriptor(key: "date", ascending: true)
            fetchRequest.sortDescriptors = [sortDescriptor]
            fetchedResultsController?.fetchRequest.predicate? = predicate
            print(fetchedResultsController?.fetchRequest.predicate) // this is always nil. Why????????????
            do {
                try fetchedResultsController?.performFetch()
            }catch{}
            print("results array: \(results)") // this array should have values of the table view, but is empty. Why ?????????????????
            fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managedObjectContext!,
                sectionNameKeyPath: "fruit", cacheName: nil)
            fetchedResultsController?.delegate = self
            tableView.reloadData() 
        }
    }

Answer 1

您想在获取的结果控制器上设置谓词。

在获取的结果控制器上更改了获取请求后，您需要调用performFetch()让它重新获取其数据。然后在表格视图上调用reloadData()。

由于语言，区域设置和Unicode的交互方式，文本搜索非平凡的示例可能很难做到正确。我推荐书中的 Text 章节：https://www.objc.io/books/core-data/

Answer 2

如果要实现可搜索的tableView？您必须使用UISearchResultsUpdating协议方法而不是名为UISearchBarDelegate的{{1}}协议方法。当searchBar:textDidChange协议方法不可用时，您可以使用searchBar:textDidChange方法！这两个类都很有用且功能强大。并且易于实施

SearchBar＆amp;使用Swift在Coredata中显示表格视图？

2 个答案: