Question

我已经按照developer.apple.com上的教程在Xcode中使用swift在表格视图中创建了一个配方应用程序。我已经开始转换为集合视图，但很难正确编写函数来展开和调整配方的数据更改。

有人可以帮忙调整代码吗？目前，它不喜欢console.time("positive"); (function() { var size = 100000; var v = 0; while (size--) { v+=(+size)%2 } })(); console.timeEnd("positive"); console.time("negative"); (function() { var size = 100000; var v = 0; while (size--) { v+=(-size)%2 } })(); console.timeEnd("negative");成员.row。 selectedindexpath

已有功能

错误

saveMeals

[在此输入图像说明] [2]

//MARK: Actions
@IBAction func unwindToMealList(sender: UIStoryboardSegue) {
    if let sourceViewController = sender.source as? MealViewController, let meal = sourceViewController.meal {

    if let selectedIndexPath =  collectionView.indexPathForSelectedRow {
        // Update an existing meal.
        meals[selectedIndexPath.row] = meal
        collectionView.reloadRows(at: [selectedIndexPath], with: .none)
    }
    else {
        // Add a new meal.
        let newIndexPath = IndexPath(row: meals.count, section: 0)

        meals.append(meal)
         collectionView.insertRows(at: [newIndexPath], with: .automatic)
    }
    // Save the meals.
    saveMeals()
    }
}

这是膳食等级

//MARK: Actions
    @IBAction func unwindToMealList(sender: UIStoryboardSegue) {
        if let sourceViewController = sender.source as? MealViewController, let meal = sourceViewController.meal {

            if let selectedIndexPath = collectionView?.numberOfSections{
                // Update an existing meal.
                meals[selectedIndexPath] = meal
                collectionView?.reloadData()
            }
            else {
                // Add a new meal.
                meals.append(meal)
                saveMeals()
                collectionView?.reloadData()

                       }
    }




}

导航

import UIKit
import os.log

class Meal: NSObject, NSCoding {

    //MARK: Properties

    var name: String
    var photo: UIImage?
    var method: String?
    var ingredients: String?



    //MARK: Archiving Paths

    static let DocumentsDirectory = FileManager().urls(for: .documentDirectory, in: .userDomainMask).first!
    static let ArchiveURL = DocumentsDirectory.appendingPathComponent("meals")


    //MARK: Types

    struct PropertyKey {
        static let name = "name"
        static let photo = "photo"
        static let method = "method"
        static let ingredients = "ingredients"


    }

    //MARK: Initialization

    init?(name: String, photo: UIImage?, method: String?, ingredients: String?) {

        // The name must not be empty
        guard !name.isEmpty else {
            return nil
        }



        // Initialize stored properties.
        self.name = name
        self.photo = photo
        self.method = method
        self.ingredients = ingredients


    }

    //MARK: NSCoding
    func encode(with aCoder: NSCoder) {
        aCoder.encode(name, forKey: PropertyKey.name)
        aCoder.encode(photo, forKey: PropertyKey.photo)
        aCoder.encode(method, forKey: PropertyKey.method)
        aCoder.encode(ingredients, forKey: PropertyKey.ingredients)

    }

    required convenience init?(coder aDecoder: NSCoder) {

        // The name is required. If we cannot decode a name string, the initializer should fail.
        guard let name = aDecoder.decodeObject(forKey: PropertyKey.name) as? String else {
            os_log("Unable to decode the name for a Meal object.", log: OSLog.default, type: .debug)
            return nil
        }

        // Because photo is an optional property of Meal, just use conditional cast.
        let photo = aDecoder.decodeObject(forKey: PropertyKey.photo) as? UIImage

        let method = aDecoder.decodeObject(forKey: PropertyKey.method) as? String

        let ingredients = aDecoder.decodeObject(forKey: PropertyKey.ingredients) as? String



        // Must call designated initializer.
        self.init(name: name, photo: photo, method: method, ingredients: ingredients)

    }    }

Answer 1

好的，首先你需要了解这些collectionview属性，比如indexpath和stuff只能在collectionview的委托方法中使用，而不是在它们之外。

现在在您的代码中，您可以这样做。添加部分很容易。只需添加reloadData来电

即可

所以你将你的食物添加到你的数组列表中然后调用上面的方法

meals.append(meal)
saveMeals()
collectionView.reloadData()

棘手的部分是你如何编辑。因此，在编辑你可以做的事情是在你正在获得餐饮的价值，你还需要得到一些标识，用于编辑哪一餐，可能是餐饮ID。

然后在您的arrayList中，您只能编辑已编辑的ID的Meal对象，然后保存它。然后拨打collectionView.reloadData()。

或者你也可以做的是当你进行编辑时，将indexpath的indexpath传递给下一个ViewController并将其设置为属性。当您执行展开segue时，从sourceViewController.selectedIndexPathProperty之类的内容中获取该属性，然后在此处按照您目前使用它的方式使用它。

展开Segue以保存到集合视图中

错误

1 个答案: