10 little UIKit ideas it is best to know

Customized UIColor with darkish mode help

Darkish mode and lightweight mode should not comply with the very same design patterns, typically you want to make use of a border when your app is in gentle mode, however in darkish mode you would possibly need to cover the additional line.

One attainable resolution is to outline a customized UIColor based mostly the given UITraitCollection. You possibly can test the userInterfaceStyle property of a trait to test for darkish look type.

extension UIColor {
    static var borderColor: UIColor {
        .init { (trait: UITraitCollection) -> UIColor in
            if trait.userInterfaceStyle == .darkish {
                return UIColor.clear
            }
            return UIColor.systemGray4
        }
    }
}

Primarily based on this situation you’ll be able to simply return totally different colours each for gentle and darkish mode. You possibly can create your personal set of static coloration variables by extending the UIColor object. It is a will need to have little trick if you’re planning to help darkish mode and also you’d wish to create customized colours. 🌈

Observing trait assortment modifications

This subsequent one can be associated to darkish mode help, typically you’d wish to detect look modifications of the person interface and that is the place the traitCollectionDidChange perform might be useful. It is out there on views, controllers and cells too, so it is fairly an common resolution.

class MyCustomView: UIView {
    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        guard traitCollection.hasDifferentColorAppearance(comparedTo: previousTraitCollection) else {
            return
        }
        layer.borderColor = UIColor.borderColor.cgColor
    }
}

For instance, inside this perform you’ll be able to test if the trait assortment has a distinct look type and you’ll replace your CoreGraphics layers based on that. The CoreGraphics framework is a low stage instrument and in case you work with layers and colours it’s a must to manually replace them if it involves darkish mode help, however the traitCollectionDidChange technique may help you numerous. 💡

UIButton with context menus

Creating buttons bought lots simpler with iOS 15, however do you know that you would be able to additionally use a button to show a context menu? It’s totally simple to current a UIMenu you simply need to set the menu and the showsMenuAsPrimaryAction property of the button to true.

import UIKit

class TestViewController: UIViewController {
    
    weak var button: UIButton!

    override func loadView() {
        tremendous.loadView()
     
        let button = UIButton(body: .zero)
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)
        self.button = button

        NSLayoutConstraint.activate([
            button.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            button.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            button.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            button.heightAnchor.constraint(equalToConstant: 44),
        ])
    }

    override func viewDidLoad() {
        tremendous.viewDidLoad()

        button.setTitle("Open menu", for: .regular)
        button.setTitleColor(.systemGreen, for: .regular)
        button.menu = getContextMenu()
        button.showsMenuAsPrimaryAction = true
    }

    func getContextMenu() -> UIMenu {
        .init(title: "Menu",
              kids: [
                UIAction(title: "Edit", image: UIImage(systemName: "square.and.pencil")) { _ in
                    print("edit button clicked")
                },
                UIAction(title: "Delete", image: UIImage(systemName: "trash"), attributes: .destructive) { _ in
                    print("delete action")
                },
              ])
    }
    
}

This manner the UIButton will act as a menu button, you’ll be able to assign numerous actions to your menu merchandise. I consider this API is particularly helpful in some circumstances, these days I desire to make use of context menus as a substitute of swipe-to-x-y actions, as a result of it is a bit extra handy for the person if we visually present them (normally with 3 dots) that there are extra actions out there on a given UI aspect. 🧐

Do not be afraid of subclassing views

UIKit is an OOP framework and I extremely suggest to subclass customized views as a substitute of multi-line view configuration code snippets inside your view controller. The earlier code snippet is a superb instance for the other, so let’s repair that actual fast.

import UIKit

class MenuButton: UIButton {

    @out there(*, unavailable)
    override init(body: CGRect) {
        tremendous.init(body: body)
        
        self.initialize()
    }

    @out there(*, unavailable)
    required public init?(coder: NSCoder) {
        tremendous.init(coder: coder)
        
        self.initialize()
    }
   
    public init() {
        tremendous.init(body: .zero)
        
        self.initialize()
    }
    
    open func initialize() {
        self.translatesAutoresizingMaskIntoConstraints = false

        setTitle("Open menu", for: .regular)
        setTitleColor(.systemGreen, for: .regular)
        menu = getContextMenu()
        showsMenuAsPrimaryAction = true
    }
    
    func getContextMenu() -> UIMenu {
        .init(title: "Menu",
              kids: [
                UIAction(title: "Edit", image: UIImage(systemName: "square.and.pencil")) { _ in
                    print("edit button clicked")
                },
                UIAction(title: "Delete", image: UIImage(systemName: "trash"), attributes: .destructive) { _ in
                    print("delete action")
                },
              ])
    }

    func layoutConstraints(in view: UIView) -> [NSLayoutConstraint] {
        [
            centerYAnchor.constraint(equalTo: view.centerYAnchor),
            leadingAnchor.constraint(equalTo: view.leadingAnchor),
            trailingAnchor.constraint(equalTo: view.trailingAnchor),
            heightAnchor.constraint(equalToConstant: 44),
        ]
    }
}


class TestViewController: ViewController {
    
    weak var button: MenuButton!

    override func loadView() {
        tremendous.loadView()
     
        let button = MenuButton()
        view.addSubview(button)
        self.button = button
        NSLayoutConstraint.activate(button.layoutConstraints(in: view))
    }

    override func viewDidLoad() {
        tremendous.viewDidLoad()
        
    }
}

As you’ll be able to see the code contained in the view controller is closely diminished and many of the button configuration associated logic is now encapsulated contained in the MenuButton subclass. This method is nice as a result of you’ll be able to focus much less on view configuration and extra on your small business logic contained in the view controller. It will additionally provide help to to assume in reusable elements.

One extra be aware right here is that I are likely to create my interfaces from code that is why I mark the pointless init strategies with the @out there(*, unavailable) flag so different individuals in my workforce cannot name them unintentionally, however that is only a private choice. 😅

All the time massive navigation title

I do not learn about you, however for me all of the apps have glitches if it involves the big title function within the navigation bar. For private initiatives I’ve bought sick and uninterested in this and I merely pressure the big title show mode. It is comparatively easy, here is how you can do it.

import UIKit

class TestNavigationController: UINavigationController {

    override init(rootViewController: UIViewController) {
        tremendous.init(rootViewController: rootViewController)
        
        initialize()
    }

    @out there(*, unavailable)
    required init?(coder aDecoder: NSCoder) {
        tremendous.init(coder: aDecoder)

        initialize()
    }
    
    open func initialize() {
        navigationBar.prefersLargeTitles = true
        navigationItem.largeTitleDisplayMode = .at all times
        
        
        navigationBar.tintColor = .systemGreen
        
        let navBarAppearance = UINavigationBarAppearance()
        navBarAppearance.backgroundColor = .systemBackground
        navigationBar.standardAppearance = navBarAppearance
        navigationBar.scrollEdgeAppearance = navBarAppearance
    }
}

class TestViewController: UIViewController {
    
    override func loadView() {
        tremendous.loadView()
        
        
        view.addSubview(UIView(body: .zero))
        
        
    }
}

let controller = TestNavigationController(rootViewController: TestViewController())

You simply need to set two properties (you’ll be able to subclass UINavigationController or set these inside your view controller, however I desire subclassing) plus it’s a must to add an empty view to your view hierarchy to stop collapsing if you’re planning to make use of a UIScrollView, UITableView or UICollectionView contained in the view controller.

Since this tip can be based mostly on my private choice, I’ve additionally included a number of extra customization choices within the snippet. Should you check out the initialize technique you’ll be able to see how you can change the tint coloration and the background coloration of the navigation bar. 👍

Customized separators for navigation and tab bars

Since many apps desire to have a personalized navigation bar and tab bar look it is fairly a standard apply when it’s a must to additionally add a separator line to differentiate person interface parts a bit extra. That is how one can resolve it through the use of a single bar separator class.

import UIKit 

class BarSeparator: UIView {
    
    let peak: CGFloat = 0.3

    init() {
        tremendous.init(body: CGRect(x: 0, y: 0, width: 0, peak: peak))
        
        translatesAutoresizingMaskIntoConstraints = false
        backgroundColor = .systemGray4
    }
    
    @out there(*, unavailable)
    required init?(coder: NSCoder) {
        tremendous.init(coder: coder)
    }
    
    func layoutConstraints(for navigationBar: UINavigationBar) -> [NSLayoutConstraint] {
        [
            widthAnchor.constraint(equalTo: navigationBar.widthAnchor),
            heightAnchor.constraint(equalToConstant: CGFloat(height)),
            centerXAnchor.constraint(equalTo: navigationBar.centerXAnchor),
            topAnchor.constraint(equalTo: navigationBar.bottomAnchor),
        ]
    }
    
    func layoutConstraints(for tabBar: UITabBar) -> [NSLayoutConstraint] {
        [
            widthAnchor.constraint(equalTo: tabBar.widthAnchor),
            heightAnchor.constraint(equalToConstant: CGFloat(height)),
            centerXAnchor.constraint(equalTo: tabBar.centerXAnchor),
            topAnchor.constraint(equalTo: tabBar.topAnchor),
        ]
    }
}

class MyNavigationController: UINavigationController {
    
   override func viewDidLoad() {
        tremendous.viewDidLoad()
        
        let separator = BarSeparator()
        navigationBar.addSubview(separator)
        NSLayoutConstraint.activate(separator.layoutConstraints(for: navigationBar))
    }
}

class MyTabBarController: UITabBarController {
    
    override func viewDidLoad() {
        tremendous.viewDidLoad()
        
        let separator = BarSeparator()
        tabBar.addSubview(separator)
        NSLayoutConstraint.activate(separator.layoutConstraints(for: tabBar))
    }   
}

This manner you’ll be able to reuse the BarSeparator part so as to add a line to the underside of a navigation bar and to the highest of a tab bar. This snippet follows the very same rules that I confirmed you earlier than, so you need to be accustomed to the subclassing ideas by now. 🤓

Customized tab bar gadgets

I struggled rather a lot with tab bar merchandise icon alignment, however this the best way I can simply present / cover the title and align the icons to the middle of the bar if there aren’t any labels.

import UIKit

class MyTabBarItem: UITabBarItem {
    
    override var title: String? {
        get { hideTitle ? nil : tremendous.title }
        set { tremendous.title = newValue }
    }
        
    personal var hideTitle: Bool {
        true
    }

    personal func offset(_ picture: UIImage?) -> UIImage? {
        if hideTitle {
            return picture?.withBaselineOffset(fromBottom: 12)
        }
        return picture
    }
    
    
    
    public comfort init(title: String?, picture: UIImage?, selectedImage: UIImage?) {
        self.init()

        self.title = title
        self.picture = offset(picture)
        self.selectedImage = offset(selectedImage)
    }

    override init() {
        tremendous.init()
    }

    @out there(*, unavailable)
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been applied")
    }
}


tabBarItem = MyTabBarItem(title: "House", picture: UIImage(systemName: "home"), selectedImage: nil)

I might additionally like to say that SF Symbols are wonderful. If you’re not utilizing these form of icons simply but I extremely suggest to have a look. Apple made a very nice job with this assortment, there are such a lot of pretty icons that you need to use to visually enrich your app, so do not miss out. 😊

loadView vs viewDidLoad

Lengthy story quick, it is best to at all times instantiate and place constraints to your views contained in the loadView technique and configure your views contained in the viewDidLoad perform.

I at all times use implicitly unwrapped weak non-compulsory variables for customized views, because the addSubview perform will create a powerful reference to the view when it’s added to the view hierarchy. We do not need to have retain cycles, proper? That’d be actual dangerous for our utility. 🙃

import UIKit

class MyCollectionViewController: ViewController {
    
    weak var assortment: UICollectionView!

    override func loadView() {
        tremendous.loadView()
        
        view.addSubview(UIView(body: .zero))
        
        let assortment = UICollectionView(body: .zero, collectionViewLayout: UICollectionViewFlowLayout())
        assortment.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(assortment)
        self.assortment = assortment
        NSLayoutConstraint.activate([
            
        ])
    }
    
    override func viewDidLoad() {
        tremendous.viewDidLoad()
        
        assortment.backgroundColor = .systemBackground
        assortment.alwaysBounceVertical = true
        assortment.dragInteractionEnabled = true
        assortment.dragDelegate = self
        assortment.dropDelegate = self

        if let flowLayout = assortment.collectionViewLayout as? UICollectionViewFlowLayout {
            flowLayout.sectionHeadersPinToVisibleBounds = true
        }
        
        assortment.register(MyCell.self,
                            forCellWithReuseIdentifier: MyCell.identifier)
    }

Anyway, I might go along with a customized subclass for the gathering view right here as nicely and possibly outline a configure technique then name that one as a substitute of inserting the whole lot on to the controller. The choice is at all times up-to-you, I am simply making an attempt to indicate you the some attainable options. 😉

Stack views & auto-layout anchors

Benefit from stack views and auto format anchors as a lot as attainable. If you’re going to create person interfaces programmatically in Swift with the assistance of UIKit, then it is going to be a vital ability to grasp these methods in any other case you are going to battle lots.

I have already got a tutorial about utilizing auto format programmatically and one other one about mastering auto-layout anchors, they had been printed a number of years in the past, however the ideas are nonetheless legitimate and the code nonetheless works. I even have yet another article that it is best to learn if you wish to be taught about constructing kinds utilizing stack views. Studying these form of issues helped me lots to create advanced screens hassle-free. I am additionally utilizing yet another “greatest apply” to create assortment views.

When SwiftUI got here out I had the sensation that ultimately I might do the identical with UIKit, however after all Apple had the mandatory tooling to help the framework with view builders and property wrappers. Now that we’ve SwiftUI I am nonetheless not utilizing it as a result of I really feel prefer it lacks various options even in 2022. I do know it is nice and I’ve created a number of prototypes for screens utilizing it, but when it involves a fancy utility my intestine tells me that I ought to nonetheless go along with UIKit. 🤐

Create a reusable elements library

My remaining recommendation on this tutorial is that it is best to construct a customized Swift package deal and transfer all of your elements there. Possibly for the primary time it is going to eat various time however if you’re engaged on a number of initiatives it should velocity up growth course of on your second, third, and so forth. app.

You possibly can transfer all of your customized base courses right into a separate library and create particular ones on your utility. You simply need to mark them open, you need to use the supply API to handle what can be utilized and what needs to be marked as unavailable.

I’ve various tutorials concerning the Swift Bundle Supervisor on my weblog, it is a nice method to get accustomed to it and you can begin constructing your personal library step-by-step. 😊