Assign xib to the UIView in Swift

Question

in objective c it can be done in init method by

-(id)init{
    self = [[[NSBundle mainBundle] loadNibNamed:@\"ViewBtnWishList\" owner:0 options:nil]     obje         


        

Answer 1

The true Swift approach is the use of protocols and protocol extensions.

I use it like this: To start I create a protocol

    protocol XibInitializable {
        static var name: String { get }
        static var bundle: Bundle? { get }

        static func fromXib() -> Self
    }

then I make a default implementation of this protocol use protocol extention

extension XibInitializable where Self : UIView {
    static var name: String {
        return String(describing: Self.self)
    }

    static var bundle: Bundle? {
        return nil
    }

    static func fromXib() -> Self {
        return UINib(nibName: name, bundle: bundle).instantiate(withOwner: nil, options: nil)[0] as! Self
    }
}

the implementation of our protocol is now complete

In order for this protocol to work, you need the name of our xib file and the class were the same. For example, for example

finally add the protocol and make your class "final", like here.

That's it

and use

Answer 2

Just subclass this simple class (swift 5):

open class NibView: UIView {

    open override func awakeAfter(using coder: NSCoder) -> Any? {
        if subviews.count == 0 {
            return UINib(nibName: "\(Self.self)", bundle: nil).instantiate(withOwner: nil, options: nil)[0] as! UIView
        }
        return self
    }
}

class CustomView: NibView {
}

As others pointed out, set File's Owner to your CustomView class (not xib's root view itself). Then set custom class to CustomView to any view that you want to be replaced by your custom view class. Also, autolayout respects all constraints inside your xib, at least as a subview of a UITableViewCell's content view. Not sure about other cases.

As simple, as it happens to be, somehow Apple did another quest for us for such a basic thing! What a wonderful company! Never gonna be bored with them!

Answer 3

This worked for me.

override func awakeAfterUsingCoder(aDecoder: NSCoder) -> AnyObject? {
    if self.subviews.count == 0 {
        return loadNib()
    }
    return self
}

private func loadNib() -> YourCustomView {
    return NSBundle.mainBundle().loadNibNamed("YourCustomViewNibName", owner: nil, options: nil)[0] as YourCustomView
}

Answer 4

I think this is the easies but also the cleanest way to assign a xib to a UIView. Xcode 7.3 and swift 2.0.

import UIKit

//Create CustomView class
class CustomView: UIView {

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

//Use it
let customView = CustomView.instanceFromNib() as! CustomView

Answer 5

for Swift 4

extension UIView {
    class func loadFromNibNamed(nibNamed: String, bundle: Bundle? = nil) -> UIView? {
      return UINib(
          nibName: nibNamed,
          bundle: bundle
      ).instantiate(withOwner: nil, options: nil)[0] as? UIView
  }
}

for Swift 3

You could create an extension on UIView:

extension UIView {
    class func loadFromNibNamed(nibNamed: String, bundle: NSBundle? = nil) -> UIView? {
        return UINib(
            nibName: nibNamed,
            bundle: bundle
        ).instantiateWithOwner(nil, options: nil)[0] as? UIView
    }
}

Note: Using UINib is faster because it does caching for you.

Then you can just do:

ViewDetailItem.loadFromNibNamed("ViewBtnWishList")

And you will be able to reuse that method on any view.

Answer 6

Just made a UINib extension to load a view from xib and embed into a container view using constraints, using generics and strong naming (without using Strings, assuming you have the same file name for xib and implementation):

extension UINib {

    static func instantiateViewAndEmbedWithConstraints <T: UIView> (viewType viewType: T.Type, embedInto containerView: UIView) -> T {
        let view = UINib(nibName: String(viewType), bundle: nil).instantiateWithOwner(nil, options: nil).first as! T
        containerView.addSubview(view)
        view.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint(item: view, attribute: .Leading, relatedBy: .Equal, toItem: containerView, attribute: .Leading, multiplier: 1, constant: 0).active = true
        NSLayoutConstraint(item: view, attribute: .Trailing, relatedBy: .Equal, toItem: containerView, attribute: .Trailing, multiplier: 1, constant: 0).active = true
        NSLayoutConstraint(item: view, attribute: .Top, relatedBy: .Equal, toItem: containerView, attribute: .Top, multiplier: 1, constant: 0).active = true
        NSLayoutConstraint(item: view, attribute: .Bottom, relatedBy: .Equal, toItem: containerView, attribute: .Bottom, multiplier: 1, constant: 0).active = true
        return view
    }

}

Usage:

...outlets...
@IBOutlet var containerView: UIView!
var customView: CustomView!

...viewDidLoad...
customView = UINib.instantiateViewAndEmbedWithConstraints(viewType: CustomView.self, embedInto: containerView)