集合视图单元格导航

Question

Dear fellow coders please help me. I started to learn Swift 2 months ago and this will be my first app if I will be able to finish... First of all, I don't use storyboard. In my app, there are collection views in main window. When you tap the image in the cells, for example the cat image in the cat cell, Cat.swift file should open. But I can't implement it yet. And in the same way if you tap the dog image, Dog.swift file should be viewed. Here is the code.

this is the main screen when you open the app:

import UIKit

class FeaturedAnimalsController: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    var animalCategories: [AnimalCategory]?

    private let cellId = "cellId"

    override func viewDidLoad() {
        super.viewDidLoad()

        animalCategories = AnimalCategory.sampleAnimalCategories()

        collectionView?.backgroundColor = .white
        collectionView?.register(CategoryCell.self, forCellWithReuseIdentifier: cellId)
    }

    func showAnimalDetailForAnimal(animal: Animal) {
        let layout = UICollectionViewFlowLayout()
        let animalDetailController = AnimalDetailController(collectionViewLayout: layout)
        animalDetailController.animal = animal
        navigationController?.pushViewController(animalDetailController, animated: true)
    }


    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        if let count = animalCategories?.count {
            return count
        }
        return 0
    }

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

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! CategoryCell

        cell.featuredAnimalsController = self

        cell.animalCategory = animalCategories?[indexPath.item]

        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: view.frame.width, height: 230)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    } 
}

This is the CategoryCell:

import UIKit

class CategoryCell: UICollectionViewCell, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {

    var featuredAnimalsController: FeaturedAnimalsController?

    var animalCategory: AnimalCategory? {
        didSet {
            if let name = animalCategory?.name {
                nameLabel.text = name
            }
        }
    }

    private let cellId = "animalCellId"

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        if let count = animalCategory?.animals?.count {
            return count
        }
        return 0
    }


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

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! AnimalCell
        cell.animal = animalCategory?.animals?[indexPath.item]
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 100, height: frame.height - 32)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 0, left: 14, bottom: 0, right: 14)
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if let animal = animalCategory?.animals![indexPath.item] {
            featuredAnimalsController?.showAnimalDetailForAnimal(animal: animal)
        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)

        setupViews()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    let nameLabel: UILabel = {
        let label = UILabel()
        label.text = "Cardiology"
        label.font = UIFont.systemFont(ofSize: 16)
        //label.numberOfLines = 1  --> DEFAULT
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()

    let animalsCollectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.backgroundColor = .clear
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        return collectionView
    }()

    func setupViews() {
        backgroundColor = .clear

        animalsCollectionView.dataSource = self
        animalsCollectionView.delegate = self

        animalsCollectionView.register(AnimalCell.self, forCellWithReuseIdentifier: cellId)


        addSubview(nameLabel)
        addSubview(animalsCollectionView)

        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-14-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": animalsCollectionView]))
        addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[nameLabel(30)][v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": animalsCollectionView, "nameLabel": nameLabel]))

    }


}

class AnimalCell: UICollectionViewCell {

    var animal: Animal? {
        didSet {
            if let name = animal?.name {
                nameLabel.text = name
            }
            categoryLabel.text = animal?.category

            if let imageName = animal?.imageName {
                imageView.image = UIImage(named: imageName)
            }
        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)

        setupViews()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func setupViews() {
        backgroundColor = .clear

        addSubview(categoryLabel)
        addSubview(imageView)
        addSubview(nameLabel)

        categoryLabel.frame = CGRect(x: 0, y: frame.width + 38, width: frame.width, height: 20)
        imageView.frame = CGRect(x: 0, y: 0, width: frame.width, height: frame.width)
        nameLabel.frame = CGRect(x: 0, y: frame.width + 2, width: frame.width, height: 40)

    }

    let imageView: UIImageView = {
        let iv = UIImageView()
        //iv.image = UIImage(named: "cat")
        iv.contentMode = .scaleAspectFill
        iv.translatesAutoresizingMaskIntoConstraints = false
        iv.layer.cornerRadius = 16
        iv.layer.masksToBounds = true
        return iv
    }()

    let nameLabel: UILabel = {
        let label = UILabel()
        label.text = ""
        label.font = UIFont.systemFont(ofSize: 14)
        label.numberOfLines = 2
        return label
    }()

    let categoryLabel: UILabel = {
        let label = UILabel()
        label.text = ""
        label.font = UIFont.systemFont(ofSize: 13)
        label.numberOfLines = 2
        return label
    }()  
}

This is the animal category model:

import UIKit

class AnimalCategory: NSObject {

    var name: String?
    var animals: [Animal]?

    static func sampleAnimalCategories() -> [AnimalCategory] {


        let catFamilyCategory = AnimalCategory()
        catFamilyCategory.name = "Cat Family"
        var catFamilyAnimals = [Animal]()

        let catAnimal = Animal()
        catAnimal.name = "Cat"
        catAnimal.imageName = "cat"
        catAnimal.category = "Lovely"
        //catAnimal.dvcName = Cat.self()
        catFamilyAnimals.append(catAnimal)

        catFamilyCategory.animals = catFamilyAnimals



        let dogFamilyCategory = AnimalCategory()
        dogFamilyCategory.name = "Dog Family"
        var dogFamilyAnimals = [Animal]()

        let dogAnimal = Animal()
        dogAnimal.name = "Dog"
        dogAnimal.imageName = "dog"
        dogAnimal.category = "Friendly"
        //dogAnimal.dvcName = Dog.self
        dogFamilyAnimals.append(dogAnimal)

        dogFamilyCategory.animals = dogFamilyAnimals


        return [catFamilyCategory, dogFamilyCategory]
    }
}

This is the animal model:

import UIKit

class Animal: NSObject {

    //var id: NSNumber?
    var name: String?
    var category: String?
    var imageName: String?
    //var dvc: AnimalDetailController?

}

This is the animal detail controller and sample cat.swift:

import UIKit

class AnimalDetailController: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    var animal: Animal? {
        didSet {
            navigationItem.title = animal?.name
        }
    }
}

class Cat: AnimalDetailController {
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .brown
    }
}

After some changes thanks to @Paulw11, here is the code to present specific detail view controller for each animal:

func showAnimalDetailFor(_ animal: Animal) {
        let layout = UICollectionViewFlowLayout()

        var dvc = animal.dvc
        dvc = AnimalDetailController(collectionViewLayout: layout)
        self.show(dvc, sender: self)
    }

Here is the animal and animal category model:

struct Animal {

    let name: String
    let category: String
    let imageName: String
    let dvc: AnimalDetailController

}

struct AnimalCategory {

    var name: String
    private var _animals = [Animal]()

    var animals: [Animal] {
        get {
            return self._animals
        }
    }

    init(name: String) {
        self.name = name
    }

    static var sampleAnimalCategories: [AnimalCategory] = {

        var dogFamily = AnimalCategory(name: "Dog Family")
        dogFamily.addAnimal(Animal(name: "Dog", category: "Friendly", imageName: "dog", dvc: DogDetailViewController()))

        var catFamily = AnimalCategory(name: "Cat Family")
        catFamily.addAnimal(Animal(name: "Cat", category: "Lovely", imageName: "cat", dvc: CatDetailViewController()))

        let categories = [dogFamily,catFamily]
        return categories
    }()

    mutating func addAnimal(_ animal: Animal) {
        self._animals.append(animal)
    }

}

And animal detail controller class:

class AnimalDetailController: UICollectionViewController, UICollectionViewDelegateFlowLayout {


    var animal: Animal? {
        didSet {
            navigationItem.title = animal?.name
        }
    }
}

I don't wont transfer data between view controllers. I am planning to make specific swift files for each animal in the cell and then when you tp their icon I want those swift file to show up. And of course I am using nav controller and set it in app delegate.

Please help me. Thank you all.

Answer 1

In general, I would caution against tightly coupling your data and your code, but you can do what you want by storing a reference to the view controller class in your data model; You almost had it correct in your commented code; you just don't need the () after self .

It is best practice to use structs if you don't need mutability, so your Animal and AnimalCategory objects could be structs. You can also avoid all of those optionals.

struct Animal {
    let name: String
    let category: String
    let imageName: String
    let dvc: AnimalDetailController.Type
}

struct AnimalCategory {

    var name: String

    private var _animals = [Animal]()

    var animals: [Animal] {
        get {
            return self._animals
        }
    }

    init(name: String) {
        self.name = name
    }

    static var sampleAnimalCategories: [AnimalCategory] = {

        var dogs = AnimalCategory(name: "Dog Family")
        dogs.addAnimal(Animal(name: "Dog", category: "Friendly", imageName: "dog", dvc: DogDetailViewController.self))

        var cats = AnimalCategory(name: "Cat Family")
        cats.addAnimal(Animal(name: "Cat", category: "Lovely", imageName: "cat", dvc: CatDetailViewController.self))

        let categories = [dogs,cats]
        return categories
    }()

    mutating func addAnimal(_ animal: Animal) {
        self._animals.append(animal)
    }

}

Then your showAnimalDetailForAnimal will be something like:

func showAnimalDetailFor(_ animal: Animal) {
    let dvc = animal.dvc.init() 
    self.show(dvc, sender: self)
}

There is also a lot of cleaning up you can do with regard to your use of optionals. For example, animals , and animalCategories could all be implicitly unwrapped optionals.

You won't be able to have your AnimalDetailViewController subclass UICollectionViewController since you can't initialise with a layout. You will need to subclass UIViewController and add the collection view in your viewDidLoad