Constructing enter types for iOS apps

This technique is just not working, since cells within the kind are going to be reused and this results in some inconsistency… please learn my different publish. 🤷‍♂️

CollectionView and enter types

My CollectionView framework simply bought a HUGE replace. There are many new modifications, however one of many greatest enchancment is the best way I take care of view fashions. Prior to now, you had to make use of lengthy operate names in your view mannequin together with the generic view & mannequin class names. When you have ever learn my final UICollectionView information you need to know what I am speaking about. Excellent news: I’ve a means higher resolution now! 😉

This replace not simply cleans up my code loads, nevertheless it permits me so as to add customized view mannequin handlers, so I can work together with enter fields, toggles, and many others. in a ridiculously straightforward means. One other large enchancment is that I began to make use of view identifiers. It was unintentional discovery, I solely needed to search for an alternate resolution for figuring out views by tags, then I had this sensible concept: why not lookup cells by ids as nicely?

Because of this I am now capable of create types by utilizing the framework. I nonetheless imagine that assortment views are the final word constructing blocks for many of the functions. Yeah, you’ll be able to nonetheless say that there isn’t a silver bullet, however I am simply effective if this resolution can cowl 90% of the my use-cases. In spite of everything, many of the apps are simply visualizing JSON information in a pleasant, or not-so-nice means. 🤷‍♂️ #sarcasm

Reusable kind parts

Let’s construct a kind by utilizing the model new framework. To start with, you will have to combine it by utilizing a bundle supervisor. I actually hope that in a couple of weeks we are able to use Swift Package deal Supervisor, till than you you need to go along with CocoaPods or carthage.

supply 'https://github.com/CoreKit/CocoaPods.git'
pod 'CollectionView', '~> 2.0.0'


github "CoreKit/CollectionView" "2.0.0"

Now let’s create a reusable cell for our enter fields. Be happy to make use of a xib file as standard, the one distinction within the implementation goes to be that I take away the goal listener within the reset technique. We’ll add one in a while within the view-model. 🎯

import Basis
import CollectionView

class InputCell: Cell {

    @IBOutlet weak var textField: UITextField!

    override func reset() {
        tremendous.reset()

        self.textField.removeTarget(nil, motion: nil, for: .editingChanged)
    }
}

I am additionally going to create a easy entity for displaying a placeholder if the shape subject is empty and storing the precise worth of the enter subject, let’s name this InputEntity.

import Basis

struct InputEntity {
    var placeholder: String
    var worth: String?
}

Now the toughest half: making a connection between the view and the mannequin.

import Basis
import CollectionView

class InputViewModel: ViewModel<InputCell, InputEntity> {

    var editingChangeHandler: ViewModelHandler?

    override var peak: CGFloat {
        return 60
    }

    override func updateView() {
        self.view?.textField.placeholder = self.mannequin.placeholder
        self.view?.textField.textual content = self.mannequin.worth

        self.view?.textField.addTarget(self,
                                       motion: #selector(self.editingChanged(_:)),
                                       for: .editingChanged)
        self.view?.textField.addTarget(self,
                                       motion: #selector(self.editingDidEnd(_:)),
                                       for: .editingDidEnd)
    }

    func onEditingChange(_ handler: @escaping ViewModelHandler) -> Self {
        self.editingChangeHandler = handler
        return self
    }

    @objc func editingChanged(_ textField: UITextField) {
        self.mannequin.worth = textField.textual content
        self.editingChangeHandler?(self)
    }

    @objc func editingDidEnd(_ textField: UITextField) {
        print("nothing-to-do-here-now...")
    }
}

It is fairly a posh view mannequin, however it might probably do loads as nicely. The very first thing that you need to perceive is the ViewModelHandler which is principally a generic alias that you may make the most of within the view fashions. It provides you the power to move across the type-safe view-model for the callbacks. You will see that in a while.

The second main change is the updateView technique, which is used to replace the view primarily based on the information coming from the mannequin. I am additionally including my goal listeners to my view, so I can deal with person enter immediately contained in the view-model class.

The onEditingChange technique is the “public” api of the view-model. I take advantage of the on prefix now for including handlers, and listeners to my view-models. It principally calls the saved block if a change occasion occurs. You may add as many occasion handler blocks as you need. I actually hope that you’re going to get the grasp of this strategy.

Yet another factor: returning the the peak of the cell is a one-liner now! 🎊

Composing types and extra

The plan is for now to have an enter kind with two enter fields. One for the e-mail handle, the opposite goes for use for the password. The trick goes to be that this time I will not present you all the code, however it’s a must to determine the remainder.

Nevertheless I will present you all the pieces that you’re going to ever have to know with the intention to make your individual types, even some complicated ones. Don’t be concerned, it is only a few traces of code.

import UIKit
import CollectionView

class ViewController: CollectionViewController {

    override func viewDidLoad() {
        tremendous.viewDidLoad()

        let grid = Grid(columns: 1, margin: UIEdgeInsets(all: 16), padding: .zero)
        self.collectionView.supply = .init(grid: grid, [
            [
                InputViewModel(id: "email-input", .init(placeholder: "Email", value: nil))
                .onEditingChange { viewModel in
                    guard let passwordViewModel = viewModel.by(id: "password-input") as? InputViewModel else {
                        return
                    }
                    passwordViewModel.model.value = viewModel.model.value ?? ""
                    passwordViewModel.updateView()
                },
                InputViewModel(id: "password-input", .init(placeholder: "Password", value: nil)),
            ],
        ])
        self.collectionView.reloadData()
    }
}

In the event you’ve ever labored with my assortment view framework, you need to know that I all the time use a grid system, as a result of I do not actually wish to calculate numbers.

The supply is a set of view-models, grouped by sections. The one attention-grabbing half right here is that sources can now be initialized with an array of sections and view-models.

In the event you initialize a view-model with and identifier, in a while you’ll be able to question that one by the id. That is precisely whats occurring contained in the modifying change handler block. Each view-model has the power to return another view-model by the id. View-models are type-safe by default, the viewModel handed contained in the block too, due to the generic ViewModelHandler alias.

So on this little instance, if you happen to kind one thing into the primary enter subject, the very same textual content will seem within the second textual content subject. You may get all of the view fashions by id while you want them. For instance if it’s a must to submit this manner, you’ll be able to seize the e-mail and password fields by utilizing the identical strategy.

Constructing a login kind

I problem you to construct a login kind by yourself by utilizing my framework. I assure yout that it should not take greater than 30mins of labor. I will present you the ultimate view controller that I might use, so this may provides you some assist.

If you wish to boost issues a bit of bit, you’ll be able to even add a checkbox for accepting the privateness coverage. The principle concept right here is that you need to create reusable parts for each single merchandise in your kind. So for instance a ToggleView with a corresponding view-model could be strategy (additionally works for buttons). 🤫

Right here is the ultimate trace, you solely need to make your individual view-models and views…

import UIKit
import CollectionView

class ViewController: CollectionViewController {

    enum Ids: String {
        case e-mail = "email-input"
        case password = "password-input"
        case privacyPolicy = "privacy-policy-checkbox"
        case submit = "submit-button"
    }

    override func viewDidLoad() {
        tremendous.viewDidLoad()

        let grid = Grid(columns: 1, margin: UIEdgeInsets(all: 16), padding: .zero)
        self.collectionView.supply = .init(grid: grid, [
            [
                InputViewModel(id: Ids.email.rawValue, .init(placeholder: "Email", value: nil))
                .onEditingEnd { viewModel in
                    guard let passwordViewModel = viewModel.by(id: Ids.password.rawValue) as? InputViewModel else {
                        return
                    }
                    passwordViewModel.view?.textField.becomeFirstResponder()
                },
                InputViewModel(id: Ids.password.rawValue, .init(placeholder: "Password", value: nil, secure: true))
                .onEditingEnd { viewModel in
                    viewModel.view?.textField.endEditing(true)
                },
            ],
            [
                ToggleViewModel(id: Ids.privacyPolicy.rawValue, .init(label: "Privacy policy", value: false))
                .onValueChange { viewModel in
                    guard let submitViewModel = viewModel.by(id: Ids.submit.rawValue) as? ButtonViewModel else {
                        return
                    }
                    var model = submitViewModel.model
                    model.enabled = viewModel.model.value
                    submitViewModel.model = model
                    submitViewModel.updateView()
                },
            ],
            [
                ButtonViewModel(id: Ids.submit.rawValue, .init(title: "Submit", enabled: false))
                .onSubmit { viewModel in
                    guard
                        let emailViewModel = viewModel.by(id: Ids.email.rawValue) as? InputViewModel,
                        let passwordViewModel = viewModel.by(id: Ids.password.rawValue) as? InputViewModel
                    else {
                        return
                    }
                    
                },
            ],
        ])
        self.collectionView.reloadData()
    }
}

That is it for now, an virtually full login kind, with only a few traces of code. After all there may be an underlying framework, however if you happen to verify the supply code, you will really see that it comprises nothing that may be thought of as black magic. 💫