Customized UIView subclass from a xib file

I have already got a complete information about initializing views and controllers, however that one lacks a really particular case: making a customized view utilizing interface builder. 🤷‍♂️

Loading xib recordsdata

Utilizing the contents of a xib file is a reasonably rattling simple process to do. You should use the next two strategies to load the contents (aka. the view hierarchy) of the file.

let view = UINib(
    nibName: "CustomView", 
    bundle: .fundamental
).instantiate(
    withOwner: nil, 
    choices: nil
).first as! UIView

 

view.body = self.view.bounds
self.view.addSubview(view)

The snippet above will merely instantiate a view object from the xib file. You possibly can have a number of root objects within the view hierarchy, however this time let’s simply decide the primary one and use that. I assume that in 99% of the instances that is what you will want as a way to get your customized views. Additionally you’ll be able to lengthen the UIView object with any of the options above to create a generic view loader. Extra on that later… 😊

This methodology is fairly easy and low-cost, nonetheless there may be one little disadvantage. You possibly can’t get named pointers (shops) for the views, however just for the foundation object. In case you are placing design parts into your display, that is superb, but when it’s good to show dynamic information, you may wish to attain out for the underlying views as properly. 😃

Customized views with shops & actions

So the correct technique to load customized views from xib recordsdata goes one thing like this:

Inside your customized view object, you instantiate the xib file precisely the identical approach as I advised you proper up right here. 👆 The one distinction is that you just needn’t use the item array returned by the strategies, however you must join your view objects by means of the interface builder, utilizing the File’s Proprietor as a reference level, plus a customized container view outlet, that’ll comprise all the pieces you want. 🤨

class CustomView: View {

    
    @IBOutlet weak var containerView: UIView!

    
    @IBOutlet weak var textLabel: UILabel!

    override func initialize() {
        tremendous.initialize()

        
        let identify = String(describing: kind(of: self))
        let nib = UINib(nibName: identify, bundle: .fundamental)
        nib.instantiate(withOwner: self, choices: nil)

        
        self.addSubview(self.containerView)
        self.containerView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            self.containerView.topAnchor.constraint(equalTo: self.topAnchor),
            self.containerView.bottomAnchor.constraint(equalTo: self.bottomAnchor),
            self.containerView.leadingAnchor.constraint(equalTo: self.leadingAnchor),
            self.containerView.trailingAnchor.constraint(equalTo: self.trailingAnchor),
        ])
    }
}

So the initialize methodology right here is simply loading the nib file with the proprietor of self. After the loading course of completed, your outlet pointers are going to be crammed with correct values from the xib file. There may be one very last thing that we have to do. Even the views from the xib file are “programmatically” linked to our customized view object, however visually they don’t seem to be. So we now have so as to add our container view into the view hierarchy. 🤐

If you wish to use your customized view object, you simply should create a brand new occasion from it – inside a view controller – and at last be at liberty so as to add it as a subview!

One phrase about bounds, frames aka. springs and struts: fucking UGLY! That is two phrases. They’re thought of as a foul observe, so please use auto structure, I’ve a pleasant tutorial about anchors, they’re superb and studying them takes about quarter-hour. 😅

class ViewController: UIViewController {

    weak var customView: CustomView!

    override func loadView() {
        tremendous.loadView()

        let customView = CustomView()
        self.view.addSubview(customView)
        NSLayoutConstraint.activate([
            customView.topAnchor.constraint(equalTo: self.view.topAnchor),
            customView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),
            customView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
            customView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
        ])
        self.customView = customView
    }

    override func viewDidLoad() {
        tremendous.viewDidLoad()

        self.customView.textLabel.textual content = "Lorem ipsum"
    }
}

That is it, now you will have a very working customized UIView object that hundreds a xib file as a way to use it is contents. Wasn’t so unhealthy, proper? 🤪

Yet another additional factor. When you do not prefer to deal with views programmatically otherwise you merely do not wish to fiddle with the loadView methodology, simply take away it totally. Subsequent put the @IBOutlet key phrase proper earlier than your customized view class variable. Open your storyboard utilizing IB, then drag & drop a brand new UIView aspect to your controller and join the customized view outlet. It ought to work like magic. 💫

I promised shops and actions within the heading of this part, so let’s discuss slightly bit about IBActions. They work precisely the identical as you’d count on them with controllers. You possibly can merely hook-up a button to your customized view and delegate the motion to the customized view class. If you wish to ahead touches or particular actions to a controller, you need to use the delegate sample or go along with a easy block. 😎

Possession and container views

It’s attainable to depart out all of the xib loading mechanism from the view occasion. We are able to create a set of extensions as a way to have a pleasant view loader with a customized view class from a xib file. This fashion you do not want a container view anymore, additionally the proprietor of the file will be omitted from the sport, it is kind of the identical methodology as reusable cells for tables and collections created by Apple. 🍎

You must know that going this manner you’ll be able to’t use your default UIView init strategies programmatically anymore, as a result of the xib file will maintain the init course of. Additionally if you’re attempting to make use of this sort of customized views from a storyboard or xib file, you will not be capable to use your shops, as a result of the correspondig xib of the view class will not be loaded. In any other case if you’re attempting to load it manyally you will run into an infinite loop and finally your app will crash like hell. 😈

import UIKit

extension UINib {
    func instantiate() -> Any? {
        return self.instantiate(withOwner: nil, choices: nil).first
    }
}

extension UIView {

    static var nib: UINib {
        return UINib(nibName: String(describing: self), bundle: nil)
    }

    static func instantiate(autolayout: Bool = true) -> Self {
        
        func instantiateUsingNib<T: UIView>(autolayout: Bool) -> T {
            let view = self.nib.instantiate() as! T
            view.translatesAutoresizingMaskIntoConstraints = !autolayout
            return view
        }
        return instantiateUsingNib(autolayout: autolayout)
    }
}

class CustomView: UIView {

    @IBOutlet weak var textLabel: UILabel!
}

Identical to with desk or assortment view cells this time you must set your customized view class on the view object, as a substitute of the File’s Proprietor. It’s important to join your shops and mainly you are performed with all the pieces. 🤞

Any more you need to ALWAYS use the instantiate methodology in your customized view object. The excellent news is that the perform is generic, returns the correct occasion kind and it is extremely reusable. Oh, btw. I already talked about the unhealthy information… 🤪

There may be additionally yet one more method by overriding awakeAfter, however I’d not depend on that answer anymore. In a lot of the instances you’ll be able to merely set the File’s Proprietor to your customized view, and go along with a container, that is a secure wager. If in case you have particular wants you may want the second method, however please watch out with that. 😉