ios - 当我输入此代码时应用程序意外退出(使用核心数据)

Question

当我输入此代码(使用核心数据)时，应用程序意外退出。我在此屏幕中使用 CoreData 对象来添加和删除数据。我不知道为什么每次进入此屏幕时此代码都会使应用程序崩溃。出现此问题:当我在核心数据对象中添加类别以及获取核心数据对象时。

核心数据.swift

class categoryCoreData {

    static func saveData(tfCat: String)
    {
        let cat = Category(context: context)
        cat.category_name = tfCat

        // Save the data to coredata
        (UIApplication.shared.delegate as! AppDelegate).saveContext()
    }

    static func fetchData() {
        do {
            addCategory = try context.fetch(Category.fetchRequest())
        }
        catch {
            print("Fetching Failed")
        }
    }
}

ViewController.swift

class CategoriesVC: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout, UITextFieldDelegate, UIGestureRecognizerDelegate
{

    @IBOutlet weak var collCategory: UICollectionView!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.collCategory.dataSource = self
        self.collCategory.delegate = self

        //categoryCoreData.fetchData()

    }


    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(true)

        self.collCategory.reloadData()
    }

    //Collection View Data-Source Methods
    func numberOfSections(in collectionView: UICollectionView) -> Int
    {
        return 1
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
    {
        return addCategory.count + 1
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
    {

        let cellID = indexPath.row < addCategory.count ? "CategoryCell" : "ExtraCell"

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellID, for: indexPath)

        setupCell(cell: cell, indexPath: indexPath, type: cellID)

        return cell
    }

    func setupCell(cell: UICollectionViewCell, indexPath: IndexPath, type: String)
    {
        switch(type)
        {
            case "CategoryCell":
                setupCategoryCell(cell: cell as! CategoryCollectionCell, indexPath: indexPath)
            case "ExtraCell":
                setupAddButtonCell(cell: cell as! CategoryExtraCell, indexPath: indexPath)
            default:
                break
        }
    }

    func setupCategoryCell(cell: CategoryCollectionCell, indexPath: IndexPath)
    {
        if indexPath.row == 0
        {
            var countedValue: Int = 0

            for i in 0..<addCategory.count
            {
                let cat = addCategory[i]
                let strCatName = cat.category_name

                filterAllTask = CategoryTaskFilteredData.filterAllCategory(filteredObject: strCatName!)

                //All the tasks counted value and add in variable countedValue
                countedValue = filterAllTask.count + countedValue
            }

            //Counted value of all tasks
            cell.lblSubHeader.text = String(format: "%d Task Added", countedValue)
            cell.lblHeader.text = "All"
        }
        else
        {
            let cat = addCategory[indexPath.row]
            cell.lblHeader.text = cat.category_name

            filterCategoryTask = CategoryTaskFilteredData.filterCategory(filteredObject: cat.category_name!)
            cell.lblSubHeader.text = String(format: "%d Task Added", filterCategoryTask.count)
        }

    }

    func setupAddButtonCell(cell: CategoryExtraCell, indexPath: IndexPath)
    {
        //Extra Button "Add Button" in a cell
    }

    //Set the CollectionViewCell size same for all iOS Devices
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
    {
        let width = collectionView.bounds.width
        let height = collectionView.bounds.height
        return CGSize(width: (width / 2 - 1),height: height / 3)
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
    {
        self.collCategory.allowsMultipleSelection = false

        if indexPath.row < addCategory.count
        {
            print("Main Cell")
            let categoryTaskVC = self.storyboard?.instantiateViewController(withIdentifier: "CategoryTaskVC") as! CategoryTaskVC

            let cat = addCategory[indexPath.row]
            categoryTaskVC.strHeader = cat.category_name!



            if indexPath.row == 0
            {
                print("entered 0")
                categoryTaskVC.selectedIndexPath = indexPath.row
            }
            else
            {
                for i in 1..<addCategory.count
                {
                    if indexPath.row == i
                    {
                        print("entered \(i)")
                        categoryTaskVC.selectedIndexPath = indexPath.row
                    }
                    else {
                        print("error")
                    }
                }
            }
            self.navigationController?.pushViewController(categoryTaskVC, animated: true)
        }
        else
        {
            print("Add New Cell")

            self.blurEffects()
            view.addSubview(blurEffectView)

            //Alert View Controller when Adding Categories...
            let inputBox = BMInputBox.boxWithStyle(.plainTextInput)
            inputBox.blurEffectStyle = .extraLight

            inputBox.title = NSLocalizedString("Add Category", comment: "")
            inputBox.message = NSLocalizedString("Please enter unique category name.", comment: "")

            inputBox.customiseInputElement = {(element: UITextField) in

                element.placeholder = "Enter a category"
                return element
            }

            inputBox.submitButtonText = NSLocalizedString("OK", comment: "")

            inputBox.onSubmit = {(value: String...) in

                //Store value in text field in "text" object.
                for text in value
                {

                    let strCategory = text

                    print("STR CATE : \(strCategory)")



                    DispatchQueue.main.async(execute: {

                        //Store category in CoreData
                        categoryCoreData.saveData(tfCat: strCategory)

                        //Fetch Category Data
                        categoryCoreData.fetchData()
                        self.collCategory.reloadData()
                    })
                }
                self.blurEffectView.removeFromSuperview()

            }


            inputBox.cancelButtonText = NSLocalizedString("Cancel", comment: "")

            inputBox.onCancel = {
                //Remove blur effects from Superview
                self.blurEffectView.removeFromSuperview()

            }
            inputBox.show()
        }

    }


    @IBAction func btnAddTask(_ sender: Any)
    {
        let addTaskVC = self.storyboard?.instantiateViewController(withIdentifier: "AddTaskVC") as! AddTaskVC
        self.navigationController?.pushViewController(addTaskVC, animated: true)
    }

}

Answer 1

这不是您的答案，但您可以找到您的应用实际崩溃的位置。

通过单击加号按钮添加异常断点并再次运行您的应用。