Home » Ios » How to initialize/instantiate a custom UIView class with a XIB file in Swift

How to initialize/instantiate a custom UIView class with a XIB file in Swift

Posted by: admin November 30, 2017 Leave a comment

Questions:

I have a class called MyClass which is a subclass of UIView, that I want to initialize with a XIB file. I am not sure how to initialize this class with the xib file called View.xib

class MyClass: UIView {

    // what should I do here? 
    //init(coder aDecoder: NSCoder) {} ?? 
}
Answers:

I tested this code and it works great

class MyClass: UIView {

    class func instanceFromNib() -> UIView {
        return UINib(nibName: "nib file name", bundle: nil).instantiateWithOwner(nil, options: nil)[0] as UIView
    }

}

Initialise the view and use it like below

    var view = MyClass.instanceFromNib()
    self.view.addSubview(view)

OR

    var view = MyClass.instanceFromNib
    self.view.addSubview(view())

UDATE Swift 3.x

class func instanceFromNib() -> UIView {
    return UINib(nibName: "nib file name", bundle: nil).instantiate(withOwner: nil, options: nil)[0] as! UIView
}

Questions:
Answers:

As of Swift 2.0, you can add a protocol extension. In my opinion, this is a better approach because the return type is Self rather than UIView, so the caller doesn’t need to cast to the view class.

import UIKit

protocol UIViewLoading {}
extension UIView : UIViewLoading {}

extension UIViewLoading where Self : UIView {

  // note that this method returns an instance of type `Self`, rather than UIView
  static func loadFromNib() -> Self {
    let nibName = "\(self)".characters.split{$0 == "."}.map(String.init).last!
    let nib = UINib(nibName: nibName, bundle: nil)
    return nib.instantiateWithOwner(self, options: nil).first as! Self
  }

}

Questions:
Answers:

Sam’s solution is already great, despite it doesn’t take different bundles into account (NSBundle:forClass comes to the rescue) and requires manual loading, a.k.a typing code.

If you want full support for your Xib Outlets, different Bundles (use in frameworks!) and get a nice preview in Storyboard try this:

// NibLoadingView.swift
import UIKit

// Usage: Subclass your UIView from NibLoadView to automatically load a xib with the same name as your class

@IBDesignable
class NibLoadingView: UIView {

    @IBOutlet weak var view: UIView!

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

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        nibSetup()
    }

    private func nibSetup() {
        backgroundColor = .clearColor()

        view = loadViewFromNib()
        view.frame = bounds
        view.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]
        view.translatesAutoresizingMaskIntoConstraints = true

        addSubview(view)
    }

    private func loadViewFromNib() -> UIView {
        let bundle = NSBundle(forClass: self.dynamicType)
        let nib = UINib(nibName: String(self.dynamicType), bundle: bundle)
        let nibView = nib.instantiateWithOwner(self, options: nil).first as! UIView

        return nibView
    }

}

Use your xib as usual, i.e. connect Outlets to File Owner and set File Owner class to your own class.

Usage: Just subclass your own View class from NibLoadingView.

No additional code required anymore.

Credits where credit’s due: Forked this with minor changes from DenHeadless on GH. My Gist: https://gist.github.com/winkelsdorf/16c481f274134718946328b6e2c9a4d8

Questions:
Answers:

And this is the answer of Frederik on Swift 3.0

@IBDesignable
class NibLoadingView: UIView {

    @IBOutlet weak var view: UIView!

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

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        nibSetup()
    }

    private func nibSetup() {
        backgroundColor = .clear

        view = loadViewFromNib()
        view.frame = bounds
        view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        view.translatesAutoresizingMaskIntoConstraints = true

        addSubview(view)
    }

    private func loadViewFromNib() -> UIView {
        let bundle = Bundle(for: type(of: self))
        let nib = UINib(nibName: String(describing: type(of: self)), bundle: bundle)
        let nibView = nib.instantiate(withOwner: self, options: nil).first as! UIView

        return nibView
    }
}

Questions:
Answers:

Universal way of loading view from xib:

Example:

let myView = Bundle.loadView(fromNib: "MyView", withType: MyView.self)

Implementation:

extension Bundle {

    static func loadView<T>(fromNib name: String, withType type: T.Type) -> T {
        if let view = Bundle.main.loadNibNamed(name, owner: nil, options: nil)?.first as? T {
            return view
        }

        fatalError("Could not load view with type " + String(describing: type))
    }
}

Questions:
Answers:

Swift 3 Answer: In my case, I wanted to have an outlet in my custom class that I could modify:

class MyClassView: UIView {
    @IBOutlet weak var myLabel: UILabel!

    class func createMyClassView() -> MyClass {
        let myClassNib = UINib(nibName: "MyClass", bundle: nil)
        return myClassNib.instantiate(withOwner: nil, options: nil)[0] as! MyClassView
    }
}

When in the .xib, make sure that the Custom Class field is MyClassView. Don’t bother with the File’s Owner.

Make sure Custom Class is MyClassView

Also, make sure that you connect the outlet in MyClassView to the label:
Outlet for myLabel

To instantiate it:

let myClassView = MyClassView.createMyClassView()
myClassView.myLabel.text = "Hello World!"

Questions:
Answers:
override func draw(_ rect: CGRect) 
{
    AlertView.layer.cornerRadius = 4
    AlertView.clipsToBounds = true

    btnOk.layer.cornerRadius = 4
    btnOk.clipsToBounds = true   
}

class func instanceFromNib() -> LAAlertView {
    return UINib(nibName: "LAAlertView", bundle: nil).instantiate(withOwner: nil, options: nil)[0] as! LAAlertView
}

@IBAction func okBtnDidClicked(_ sender: Any) {

    removeAlertViewFromWindow()

    UIView.animate(withDuration: 0.4, delay: 0.0, options: .allowAnimatedContent, animations: {() -> Void in
        self.AlertView.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)

    }, completion: {(finished: Bool) -> Void in
        self.AlertView.transform = CGAffineTransform.identity
        self.AlertView.transform = CGAffineTransform(scaleX: 0.0, y: 0.0)
        self.AlertView.isHidden = true
        self.AlertView.alpha = 0.0

        self.alpha = 0.5
    })
}


func removeAlertViewFromWindow()
{
    for subview  in (appDel.window?.subviews)! {
        if subview.tag == 500500{
            subview.removeFromSuperview()
        }
    }
}


public func openAlertView(title:String , string : String ){

    lblTital.text  = title
    txtView.text  = string

    self.frame = CGRect(x: 0, y: 0, width: screenWidth, height: screenHeight)
    appDel.window!.addSubview(self)


    AlertView.alpha = 1.0
    AlertView.isHidden = false

    UIView.animate(withDuration: 0.2, animations: {() -> Void in
        self.alpha = 1.0
    })
    AlertView.transform = CGAffineTransform(scaleX: 0.0, y: 0.0)

    UIView.animate(withDuration: 0.3, delay: 0.2, options: .allowAnimatedContent, animations: {() -> Void in
        self.AlertView.transform = CGAffineTransform(scaleX: 1.1, y: 1.1)

    }, completion: {(finished: Bool) -> Void in
        UIView.animate(withDuration: 0.2, animations: {() -> Void in
            self.AlertView.transform = CGAffineTransform(scaleX: 1.0, y: 1.0)

        })
    })


}