Swift proper way to load xib file

Question

I have some strange problem with loading xib file in swift project. It's so frustrating because I already know how to do it in Obj-C. But since swift is swift so you can't do it like you did.. :/

So I have create IconTextFiled.xib and IconTextField.swift. (extends UITextField) In xib I fill field Class in Idenity inspector and in storyboard I do the same for some textFields. So we good to go just add loading from xib to init method? No.

In objc I would do it like this

- (instancetype)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"IconTextField" owner:self options:nil];
        self = [nib objectAtIndex:0];
    }
    return self;
}

So I thought if I translate to swift it will be good.

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    let nib:NSArray = NSBundle.mainBundle().loadNibNamed("IconTextField", owner: self, options: nil)
    self = nib.objectAtIndex(0)
}

But that doeasn't work. I don't know why but it try to create much more object and crash

Finally I found extension

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

So in ViewController it looks like

@IBOutlet var password: IconTextField!
override func viewDidLoad() {
    super.viewDidLoad()
    password = IconTextField.loadFromNibNamed("IconTextField")
}

And again fail. Could you tell me how you load and use xib files?

UPDATE

Ok following after Daniel anwser

My current code

class IconTextField: UITextField {
    @IBOutlet var icon: UIImageView!
    @IBOutlet weak var view: UIView!

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        NSLog("initWithCoder \(self)")
        NSBundle.mainBundle().loadNibNamed("IconTextField", owner: self, options: nil)
        self.addSubview(view)
    }   
}

Those two var are connected to those views

Consoleo output, was a lot bigger and end with EXC_BAD_ACCESS

2014-10-24 10:09:09.984 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7be7bfb0;>
2014-10-24 10:09:09.984 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7be7ddf0;>
2014-10-24 10:09:09.985 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7be7fa20;>
2014-10-24 10:09:09.985 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7be814f0;>
2014-10-24 10:09:09.986 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7be830c0;>
2014-10-24 10:09:10.083 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7d183270;>
2014-10-24 10:09:10.084 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7d187cd0;>
2014-10-24 10:09:10.084 testproject[20337:3757479] initWithCoder <stensgroup.IconTextField: 0x7d189960;>

It should be only two initWithCoder. It seams that func loadNibNamed is calling initWithCoder

Answer 1

This works for me:

class IconTextField: UITextField {
    @IBOutlet weak var view: UIView!
    @IBOutlet weak var test: UIButton!

    required init(coder: NSCoder) {
        super.init(coder: coder)
        NSBundle.mainBundle().loadNibNamed("IconTextField", owner: self, options: nil)
        self.addSubview(view)
        assert(test != nil, "the button is conected just like it's supposed to be")
    }
}

Once loadNibNamed:owner:options: is called the view and test button are connected to the outlets as expected. Adding the nib's view self's subview hierarchy makes the nib's contents visible.

Answer 2

I prefer to load from nib, by implementing loadFromNib() function in a protocol extension as follows:

(as explained here: https://stackoverflow.com/a/33424509/845027)

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
  }

}

Answer 3

You can use this:

if let customView = Bundle.main.loadNibNamed("MyCustomView", owner: self, options: nil)?.first as? MyCustomView {
        // Set your view here with instantiated customView
}