我是 iOS 开发的新手，正在使用 Swift 开发我的第二个应用程序。我无法在我的表格视图控制器中合并 SearchBar 和显示搜索。
我的应用中有 2 个视图。First View 生成一个水果数组。第一个视图的输出：[苹果、橙子、香蕉、梨]。然后是【石榴、梨、西瓜、香瓜】等等。一次一个数组。
每个水果数组都使用 NSFetchedResultsController 存储在核心数据中，以显示在 tableviewcontroller 中。我的核心数据布局：
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。现在我在表格视图的顶部添加了一个搜索栏和显示。但我无法让它发挥作用。
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")
我班有两个插座：
@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 中搜索任何水果并过滤视图？Swift 编码中的搜索栏和显示功能应该使用哪个委托函数？
任何我可能在这里错过的概念的帮助将不胜感激！谢谢。
更新：正如 Daniel Eggert 建议的那样，我正在尝试将谓词用于搜索控制器功能，但谓词总是给出nil。我错过了什么？？？
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()
}
}