Uiview and Initwithframe and a Nib File. How to Get the Nib File Loaded

UIView and initWithFrame and a NIB file. How can I get the NIB file loaded?

You have many options, depending on how your "baseView" class is meant to be used and integrated in to your application. It's not clear just how you intend to use this class -- as the view in a UIViewController subclass, or as a reusable modular component mean to be instantiated multiple times throughout your application, for use in many different view controllers.

If your view is meant to be the only view in a UIViewController subclass, then Phonitive is correct -- bundle it together with the UIViewController subclass .xib file and use the UIViewController's viewDidLoad to do final initialization.

But if you want your View class to be a subcomponent reused multiple times in different view controllers, integrated either via code or via inclusion in a .xib file for another controller, then you need to implement both the initWithFrame: init method, and awakeFromNib, to handle both cases. If your internal initialization always includes some objects from .xib, then in your initWithFrame you'll need to load your .xib manually in order to support "customer" classes that want to create your widget via code. And likewise, if a .xib file contains your object then you'll need to make sure you call any code-required finalization from awakeFromNib.

Here's an example of how to create a UIView subclass component with the UI design in a nib.

MyView.h:

@interface MyView : UIView
{
    UIView *view;
    UILabel *l;
}
@property (nonatomic, retain) IBOutlet UIView *view;
@property (nonatomic, retain) IBOutlet UILabel *l;

MyView.m:

#import "MyView.h"
@implementation MyView
@synthesize l, view;

- (id)initWithFrame:(CGRect)frame 
{
    self = [super initWithFrame:frame];
    if (self) 
    {
        // Initialization code.
        //
        [[NSBundle mainBundle] loadNibNamed:@"MyView" owner:self options:nil];
        [self addSubview:self.view];
    }
    return self;
}

- (void) awakeFromNib
{
    [super awakeFromNib];

    // commenters report the next line causes infinite recursion, so removing it
    // [[NSBundle mainBundle] loadNibNamed:@"MyView" owner:self options:nil];
    [self addSubview:self.view];
}

- (void) dealloc
{
     [l release];
     [view release];
     [super dealloc];
}

Here's what the nib file looks like (except that file's owner needs to be changed to MyView class).

be sure to hook up both the view and label outlets to File's Owner. That's it! A template for creating re-usable UIView widgets.

The really neat thing about this structure is that you can place instances of your MyView object in other nib files, just place a UIView at the location/size you want, then change the class in the identity inspector (CMD-4) to MyView, and boom, you've got an instance of your widget in whatever views you want! Just like UIKit objects you can implement delegate protocols so that objects using your widget can be notified of interesting events, and can provide data to display in the widget to customize it.

Load a UIView from nib in Swift

Original Solution

1. I created a XIB and a class named SomeView (used the same name for
   convenience and readability). I based both on a UIView.
2. In the XIB, I changed the "File's Owner" class to SomeView (in the identity inspector).
3. I created a UIView outlet in SomeView.swift, linking it to the top level view in the XIB file (named it "view" for convenience). I then added other outlets to other controls in the XIB file as needed.
4. in SomeView.swift, I loaded the XIB inside the "init with code" initializer. There is no need to assign anything to "self". As soon as the XIB is loaded, all outlets are connected, including the top level view. The only thing missing, is to add the top view to the view hierarchy:

.

class SomeView: UIView {
   required init(coder aDecoder: NSCoder) {
      super.init(coder: aDecoder)
      NSBundle.mainBundle().loadNibNamed("SomeView", owner: self, options: nil)
      self.addSubview(self.view);    // adding the top level view to the view hierarchy
   }
   ...
}

Note that this way I get a class that loads itself from nib. I could then use SomeView as a class whenever UIView could be used in the project (in interface builder or programmatically).

Update - using Swift 3 syntax

Loading a xib in the following extension is written as an instance method, which can then be used by an initializer like the one above:

extension UIView {

    @discardableResult   // 1
    func fromNib() -> T? {   // 2
        guard let contentView = Bundle(for: type(of: self)).loadNibNamed(String(describing: type(of: self)), owner: self, options: nil)?.first as? T else {    // 3
            // xib not loaded, or its top view is of the wrong type
            return nil
        }
        self.addSubview(contentView)     // 4
        contentView.translatesAutoresizingMaskIntoConstraints = false   // 5 
        contentView.layoutAttachAll(to: self)   // 6 
        return contentView   // 7
    }
}

1. Using a discardable return value since the returned view is mostly of no interest to caller when all outlets are already connected.
2. This is a generic method that returns an optional object of type UIView. If it fails to load the view, it returns nil.
3. Attempting to load a XIB file with the same name as the current class instance. If that fails, nil is returned.
4. Adding the top level view to the view hierarchy.
5. This line assumes we're using constraints to layout the view.
6. This method adds top, bottom, leading & trailing constraints - attaching the view to "self" on all sides (See: https://stackoverflow.com/a/46279424/2274829 for details)
7. Returning the top level view

And the caller method might look like this:

final class SomeView: UIView {   // 1.
   required init?(coder aDecoder: NSCoder) {   // 2 - storyboard initializer
      super.init(coder: aDecoder)
      fromNib()   // 5.
   }
   init() {   // 3 - programmatic initializer
      super.init(frame: CGRect.zero)  // 4.
      fromNib()  // 6.
   }
   // other methods ...
}

1. SomeClass is a UIView subclass that loads its content from a SomeClass.xib file. The "final" keyword is optional.
2. An initializer for when the view is used in a storyboard (remember to use SomeClass as the custom class of your storyboard view).
3. An initializer for when the view is created programmatically (i.e.: "let myView = SomeView()").
4. Using an all-zeros frame since this view is laid out using auto-layout.
   Note that an "init(frame: CGRect) {..}" method is not created independently, since auto-layout is used exclusively in our project.
5. & 6. Loading the xib file using the extension.

Credit: Using a generic extension in this solution was inspired by Robert's answer below.

Edit
Changing "view" to "contentView" to avoid confusion. Also changed the array subscript to ".first".

Correct way to load a Nib for a UIView subclass

MyViewClass *myViewObject = [[[NSBundle mainBundle] loadNibNamed:@"MyViewClassNib" owner:self options:nil] objectAtIndex:0]

I'm using this to initialise the reusable custom views I have.

---

Note that you can use "firstObject" at the end there, it's a little cleaner. "firstObject" is a handy method for NSArray and NSMutableArray.

Here's a typical example, of loading a xib to use as a table header. In your file YourClass.m

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    return [[NSBundle mainBundle] loadNibNamed:@"TopArea" owner:self options:nil].firstObject;
}

Normally, in the TopArea.xib, you would click on File Owner and set the file owner to YourClass. Then actually in YourClass.h you would have IBOutlet properties. In TopArea.xib, you can drag controls to those outlets.

Don't forget that in TopArea.xib, you may have to click on the View itself and drag that to some outlet, so you have control of it, if necessary. (A very worthwhile tip is that when you are doing this for table cell rows, you absolutely have to do that - you have to connect the view itself to the relevant property in your code.)

How to load a `.xib` / `.nib` file within a framework?

It should be enough to use

[NSBundle bundleForClass:[self class]]
instead of
[NSBundle mainBundle]

So basically [NSBundle mainBundle] returns bundle for current module which is your app, but not the actual framework

Here you can find more details
[NSBundle bundleForClass:[self class]]] what does that mean?

Interface Builder: How to load view from nib file

For loading the view you need to add on your window:-
Created custom class of view inheriting to NSViewController

#import 

@interface NewViewController : NSViewController

@end

#import "NewViewController.h"

@implementation NewViewController

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Initialization code here.
    }

    return self;
}

@end

Your xib name is yourview.xib

- (void)windowDidLoad {
    NSViewController *yourVC = [[NewViewController alloc] initWithNibName:@"NewViewController" bundle:nil];
    [[[self window] contentView] addSubview:[yourVC view]];
}

Nib-file loaded UIView in UITableViewCell does not stretch

I solved it by also adding a width constraint matching the tableViews width. This is code from CustomTableViewCell:

public override func layoutSubviews() {
    super.layoutSubviews()

    if let width = tableView()?.frame.width, !haveAddedWidthConstraint {
        haveAddedWidthConstraint = true
        rowView.addWidthConstraint(width: width)
    }
}

UIViewExtension:

public func addWidthConstraint(width: CGFloat) {
    let widthConstraint = NSLayoutConstraint(item: self, attribute: .width, relatedBy: .greaterThanOrEqual, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: width)
    widthConstraint.priority = 1000
    addConstraint(widthConstraint)
}

UITableViewCellExtension:

func tableView() -> UITableView? {
    var currentView: UIView = self
    while let superView = currentView.superview {
        if superView is UITableView {
            return (superView as! UITableView)
        }
        currentView = superView
    }
    return nil
}

---

Related Topics