使用 Swift 使用 Core Data 对象填充 UIPickerView

Posted 2023-03-04

【中文标题】使用 Swift 使用 Core Data 对象填充 UIPickerView

【英文标题】：Populating UIPickerView with Core Data objects using Swift

【发布时间】：2015-06-11 03:50:55

【问题描述】：

我正在尝试在 Swift 应用中使用 Core Data 对象填充 UIPickerView。

现在，我得到一个有 4 行的选择器视图（Core Data 实体中有 4 个对象）。我的问题是所有 4 行标题都来自同一个对象。请看截图：

这是我目前的一段代码：

override func viewWillAppear(animated: Bool) 
    
    getFetchedResultController_cat(currentEntity_cat)



func getFetchedResultController_cat(selectedEntity: NSString)
    
    let appDelegate : AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    let managedObjectContext: NSManagedObjectContext = appDelegate.managedObjectContext!
    
    let fetchRequest = NSFetchRequest()
    
    let entity = NSEntityDescription.entityForName(selectedEntity as String, inManagedObjectContext: managedObjectContext)
    
    fetchRequest.entity = entity
    
    fetchRequest.fetchBatchSize = 20
 
    let sectionSortDescriptor = NSSortDescriptor(key: "name", ascending: true)
    
    let sortDescriptors = [sectionSortDescriptor] //, secondSortDescriptor]
    
    fetchRequest.sortDescriptors = sortDescriptors
    
    let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managedObjectContext, sectionNameKeyPath: nil, cacheName: nil)
    
    aFetchedResultsController.delegate = self
    self.fetchedResultsController_cat = aFetchedResultsController
    
    var error: NSError? = nil
    if !self.fetchedResultsController_cat.performFetch(&error) 
        abort()
    
    let x : Int = (self.fetchedResultsController_cat.fetchedObjects?.count ?? 0)
    println("CATEGORIAS ACTUALES=")
    println(x)
    self.pickerView.reloadAllComponents()


func pickerView(pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat 
    return 100

//size the components of the UIPickerView
func pickerView(pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat 
    return 20.0

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int 
    return 1


func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
    return fetchedResultsController_cat.fetchedObjects?.count ?? 0


func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! 
  
    let indexPath = NSIndexPath(forRow: 0, inSection: 0)
    let fetchedObject: AnyObject = self.fetchedResultsController_cat.objectAtIndexPath(indexPath)
    print (fetchedObject.valueForKey("name"))
    var nombre: AnyObject? = fetchedObject.valueForKey("name")
    return nombre as! String

我想在每一行显示正确的行标题。

我的代码中缺少什么？

谢谢。

【参考方案1】：

您似乎总是在获取 fetch 结果中检索第一个元素：

尝试改变这个：

let indexPath = NSIndexPath(forRow: 0, inSection: 0) 

到这里：

let indexPath = NSIndexPath(forRow: row, inSection: 0)

【讨论】：

它按照您的建议工作。谢谢伊卡罗。我必须等待 7 分钟才能接受您的回答.... :)

@mvasco 很高兴来到这里！祝你的应用好运！ （感谢您的投票）