How to load a UIView using a nib file created with

问题:

I\'m trying to do something a bit elaborate, but something that should be possible. So here is a challenge for all you experts out there (this forum is a pack of a lot of you guys :) ).

I\'m creating a Questionnaire \"component\", which I want to load on a NavigationContoller (my QuestionManagerViewController). The \"component\" is an \"empty\" UIViewController, which can load different views depending on the question that needs to be answered.

The way I\'m doing it is:

1. Create Question1View object as a UIView subclass, defining some IBOutlets.
2. Create (using Interface Builder) the Question1View.xib (HERE IS WHERE MY PROBLEM PROBABLY IS). I set both the UIViewController and the UIView to be of class Question1View.
3. I link the outlets with the view\'s component (using IB).

4. I override the initWithNib of my QuestionManagerViewController to look like this:

   - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
       if (self = [super initWithNibName:@\"Question1View\" bundle:nibBundleOrNil]) {
           // Custom initialization
       }
       return self;
   }
   

When I run the code, I\'m getting this error:

2009-05-14 15:05:37.152 iMobiDines[17148:20b] *** Terminating app due to uncaught exception \'NSInternalInconsistencyException\', reason: \'-[UIViewController _loadViewFromNibNamed:bundle:] loaded the \"Question1View\" nib but the view outlet was not set.\'

I\'m sure there is a way to load the view using the nib file, without needing to create a viewController class.

回答1:

There is also an easier way to access the view instead of dealing with the nib as an array.

1) Create a custom View subclass with any outlets that you want to have access to later. --MyView

2) in the UIViewController that you want to load and handle the nib, create an IBOutlet property that will hold the loaded nib\'s view, for instance

in MyViewController (a UIViewController subclass)

  @property (nonatomic, retain) IBOutlet UIView *myViewFromNib;

(dont forget to synthesize it and release it in your .m file)

3) open your nib (we\'ll call it \'myViewNib.xib\') in IB, set you file\'s Owner to MyViewController

4) now connect your file\'s Owner outlet myViewFromNib to the main view in the nib.

5) Now in MyViewController, write the following line:

[[NSBundle mainBundle] loadNibNamed:@\"myViewNib\" owner:self options:nil];

Now as soon as you do that, calling your property \"self.myViewFromNib\" will give you access to the view from your nib!

回答2:

Thank you all. I did find a way to do what I wanted.

1. Create your UIView with the IBOutlets you need.
2. Create the xib in IB, design it to you liking and link it like this: The File\'s Owner is of class UIViewController (No custom subclass, but the \"real\" one). The File Owner\'s view is connected to the main view and its class is declared as the one from step 1).
3. Connect your controls with the IBOutlets.

4. The DynamicViewController can run its logic to decide what view/xib to load. Once its made the decission, in the loadView method put something like this:

   NSArray* nibViews = [[NSBundle mainBundle] loadNibNamed:@\"QPickOneView\"
                                                     owner:self
                                                   options:nil];
   
   QPickOneView* myView = [ nibViews objectAtIndex: 1];
   
   myView.question = question;
   

That\'s it!

The main bundle\'s loadNibNamed method will take care of initializing the view and creating the connections.

Now the ViewController can display a view or another depending on the data in memory, and the \"parent\" screen doesn\'t need to bother with this logic.

回答3:

I\'m not sure what some of the answers are talking about, but I need to put this answer here for when I search in Google next time. Keywords: \"How to load a UIView from a nib\" or \"How to load a UIView from an NSBundle.\"

Here\'s the code almost 100% straight up from the Apress Beginning iPhone 3 book (page 247, \"Using The New Table View Cell\"):

- (void)viewDidLoad {
    [super viewDidLoad];
    NSArray *bundle = [[NSBundle mainBundle] loadNibNamed:@\"Blah\"
                                                 owner:self options:nil];
    Blah *blah;
    for (id object in bundle) {
        if ([object isKindOfClass:[Blah class]]) {
            blah = (Blah *)object;
            break;
        }
    }   
    assert(blah != nil && \"blah can\'t be nil\");
    [self.view addSubview: blah];
} 

This supposes you have a UIView subclass called Blah, a nib called Blah which contains a UIView which has its class set to Blah.

---

Category: NSObject+LoadFromNib

#import \"NSObject+LoadFromNib.h\"

@implementation NSObject (LoadFromNib)

+ (id)loadFromNib:(NSString *)name classToLoad:(Class)classToLoad {
    NSArray *bundle = [[NSBundle mainBundle] loadNibNamed:name owner:self options:nil];
    for (id object in bundle) {
        if ([object isKindOfClass:classToLoad]) {
            return object;
        }
    }
    return nil;
}

@end

---

Swift Extension

extension UIView {
    class func loadFromNib<T>(withName nibName: String) -> T? {
        let nib  = UINib.init(nibName: nibName, bundle: nil)
        let nibObjects = nib.instantiate(withOwner: nil, options: nil)
        for object in nibObjects {
            if let result = object as? T {
                return result
            }
        }
        return nil
    }
}

And an example in use:

class SomeView: UIView {
    class func loadFromNib() -> SomeView? {
        return self.loadFromNib(withName: \"SomeView\")
    }
}

回答4:

For all those that need to manage more than one instance of the custom view, that is an Outlet Collection, I merged and customized the @Gonso, @AVeryDev and @Olie answers in this way:

1. Create a custom MyView : UIView and set it as \"Custom Class\" of the root UIView in the desired XIB;

2. Create all outlets you need in MyView (do it now because after point 3 the IB will propose you to connect outlets to the UIViewController and not to the custom view as we want);

3. Set your UIViewController as \"File\'s Owner\" of the custom view XIB;

4. In the UIViewController add a new UIViews for each instance of MyView you want, and connect them to UIViewController creating an Outlet Collection: these views will act as \"wrapper\" views for the custom view instances;

5. Finally, in the viewDidLoad of your UIViewController add the following lines:

NSArray *bundleObjects;
MyView *currView;
NSMutableArray *myViews = [NSMutableArray arrayWithCapacity:myWrapperViews.count];
for (UIView *currWrapperView in myWrapperViews) {
    bundleObjects = [[NSBundle mainBundle] loadNibNamed:@\"MyView\" owner:self options:nil];
    for (id object in bundleObjects) {
        if ([object isKindOfClass:[MyView class]]){
            currView = (MyView *)object;
            break;
        }
    }

    [currView.myLabel setText:@\"myText\"];
    [currView.myButton setTitle:@\"myTitle\" forState:UIControlStateNormal];
    //...

    [currWrapperView addSubview:currView];
    [myViews addObject:currView];
}
//self.myViews = myViews; if need to access them later..

回答5:

I would use UINib to instantiate a custom UIView to be reused

UINib *customNib = [UINib nibWithNibName:@\"MyCustomView\" bundle:nil];
MyCustomViewClass *customView = [[customNib instantiateWithOwner:self options:nil] objectAtIndex:0];
[self.view addSubview:customView];

Files needed in this case are MyCustomView.xib, MyCustomViewClass.h and MyCustomViewClass.m Note that [UINib instantiateWithOwner] returns an array, so you should use the element which reflects the UIView you want to re-use. In this case it\'s the first element.

回答6:

You should not be setting the class of your view controller to be a subclass of UIView in Interface Builder. That is most definitely at least part of your problem. Leave that as either UIViewController, some subclass of it, or some other custom class you have.

As for loading only a view from a xib, I was under the assumption that you had to have some sort of view controller (even if it doesn\'t extend UIViewController, which may be too heavyweight for your needs) set as the File\'s Owner in Interface Builder if you want to use it to define your interface. I did a little research to confirm this as well. This is because otherwise there would be no way to access any of the interface elements in the UIView, nor would there be a way to have your own methods in code be triggered by events.

If you use a UIViewController as your File\'s Owner for your views, you can just use initWithNibName:bundle: to load it and get the view controller object back. In IB, make sure you set the view outlet to the view with your interface in the xib. If you use some other type of object as your File\'s Owner, you\'ll need to use NSBundle\'s loadNibNamed:owner:options: method to load the nib, passing an instance of File\'s Owner to the method. All its properties will be set properly according to the outlets you define in IB.

回答7:

You can also use UIViewController\'s initWithNibName instead of loadNibNamed. It is simpler, I find.

UIViewController *aViewController = [[UIViewController alloc] initWithNibName:@\"MySubView\" bundle:nil];
[self.subview addSubview:aViewController.view];
[aViewController release];  // release the VC

Now you just have to create MySubView.xib and MySubView.h/m. In MySubView.xib set the File\'s Owner class to UIViewController and view class to MySubView.

You can position and size of the subview using the parent xib file.

回答8:

This is a great question (+1) and the answers were almost helpful ;) Sorry guys, but I had a heck of a time slogging through this, though both Gonso & AVeryDev gave good hints. Hopefully, this answer will help others.

MyVC is the view controller holding all this stuff.

MySubview is the view that we want to load from a xib

• In MyVC.xib, create a view of type MySubView that is the right size & shape & positioned where you want it.

• In MyVC.h, have

  IBOutlet MySubview *mySubView
  // ...
  @property (nonatomic, retain) MySubview *mySubview;
  

• In MyVC.m, @synthesize mySubView; and don\'t forget to release it in dealloc.

• In MySubview.h, have an outlet/property for UIView *view (may be unnecessary, but worked for me.) Synthesize & release it in .m
• In MySubview.xib
  • set file owner type to MySubview, and link the view property to your view.
  • Lay out all the bits & connect to the IBOutlet\'s as desired

• Back in MyVC.m, have

  NSArray *xibviews = [[NSBundle mainBundle] loadNibNamed: @\"MySubview\" owner: mySubview options: NULL];
  MySubview *msView = [xibviews objectAtIndex: 0];
  msView.frame = mySubview.frame;
  UIView *oldView = mySubview;
  // Too simple: [self.view insertSubview: msView aboveSubview: mySubview];
  [[mySubview superview] insertSubview: msView aboveSubview: mySubview]; // allows nesting
  self.mySubview = msView;
  [oldCBView removeFromSuperview];
  

The tricky bit for me was: the hints in the other answers loaded my view from the xib, but did NOT replace the view in MyVC (duh!) -- I had to swap that out on my own.

Also, to get access to mySubview\'s methods, the view property in the .xib file must be set to MySubview. Otherwise, it comes back as a plain-old UIView.

If there\'s a way to load mySubview directly from its own xib, that\'d rock, but this got me where I needed to be.

回答9:

This is something that ought to be easier. I ended up extending UIViewController and adding a loadNib:inPlaceholder: selector. Now I can say

self.mySubview = (MyView *)[self loadNib:@\"MyView\" inPlaceholder:mySubview];

Here\'s the code for the category (it does the same rigamarole as described by Gonso):

@interface UIViewController (nibSubviews)

- (UIView *)viewFromNib:(NSString *)nibName;
- (UIView *)loadNib:(NSString *)nibName inPlaceholder:(UIView *)placeholder;

@end

@implementation UIViewController (nibSubviews)

- (UIView *)viewFromNib:(NSString *)nibName
{
  NSArray *xib = [[NSBundle mainBundle] loadNibNamed:nibName owner:self options:nil]; 
  for (id view in xib) { // have to iterate; index varies
    if ([view isKindOfClass:[UIView class]]) return view;
  }
  return nil;
}

- (UIView *)loadNib:(NSString *)nibName inPlaceholder:(UIView *)placeholder
{
  UIView *nibView = [self viewFromNib:nibName];
  [nibView setFrame:placeholder.frame];
  [self.view insertSubview:nibView aboveSubview:placeholder];
  [placeholder removeFromSuperview];
  return nibView;
}

@end

回答10:

I too wanted to do something similar, this is what I found: (SDK 3.1.3)

I have a view controller A (itself owned by a Nav controller) which loads VC B on a button press:

In AViewController.m

BViewController *bController = [[BViewController alloc] initWithNibName:@\"Bnib\" bundle:nil];
[self.navigationController pushViewController:bController animated:YES];
[bController release];

Now VC B has its interface from Bnib, but when a button is pressed, I want to go to an \'edit mode\' which has a separate UI from a different nib, but I don\'t want a new VC for the edit mode, I want the new nib to be associated with my existing B VC.

So, in BViewController.m (in button press method)

NSArray *nibObjects = [[NSBundle mainBundle] loadNibNamed:@\"EditMode\" owner:self options:nil];
UIView *theEditView = [nibObjects objectAtIndex:0];
self.editView = theEditView;
[self.view addSubview:theEditView];

Then on another button press (to exit edit mode):

[editView removeFromSuperview];

and I\'m back to my original Bnib.

This works fine, but note my EditMode.nib has only 1 top level obj in it, a UIView obj. It doesn\'t matter whether the File\'s Owner in this nib is set as BViewController or the default NSObject, BUT make sure the View Outlet in the File\'s Owner is NOT set to anything. If it is, then I get a exc_bad_access crash and xcode proceeds to load 6677 stack frames showing an internal UIView method repeatedly called... so looks like an infinite loop. (The View Outlet IS set in my original Bnib however)

Hope this helps.

回答11:

I made a category that I like:

UIView+NibInitializer.h

#import <UIKit/UIKit.h>

@interface UIView (NibInitializer)
- (instancetype)initWithNibNamed:(NSString *)nibNameOrNil;
@end

UIView+NibInitializer.m

#import \"UIView+NibInitializer.h\"

@implementation UIView (NibInitializer)

- (instancetype)initWithNibNamed:(NSString *)nibNameOrNil
{
    if (!nibNameOrNil) {
        nibNameOrNil = NSStringFromClass([self class]);
    }
    NSArray *viewsInNib = [[NSBundle mainBundle] loadNibNamed:nibNameOrNil
                                                        owner:self
                                                      options:nil];
    for (id view in viewsInNib) {
        if ([view isKindOfClass:[self class]]) {
            self = view;
            break;
        }
    }
    return self;
}

@end

Then, call like this:

MyCustomView *myCustomView = [[MyCustomView alloc] initWithNibNamed:nil];

Use a nib name if your nib is named something other than the name of your class.

To override it in your subclasses for additional behavior, it could look like this:

- (instancetype)initWithNibNamed:(NSString *)nibNameOrNil
{
    self = [super initWithNibNamed:nibNameOrNil];
    if (self) {
        self.layer.cornerRadius = CGRectGetHeight(self.bounds) / 2.0;
    }
    return self;
}

回答12:

In swift

Actually my resolution to this problem was, to load the view in a viewDidLoad in my CustonViewController where I wanted to use the view like that:

myAccessoryView = NSBundle.mainBundle().loadNibNamed(\"MyAccessoryView\", owner: self, options: nil)[0] as! MyAccessoryView

Don\'t load the view in a loadView() method! The loadView method serves for loading the view for your custom ViewController.

回答13:

I found this blog posting by Aaron Hillegass (author, instructor, Cocoa ninja) to be very enlightening. Even if you don\'t adopt his modified approach to loading NIB files through a designated initializer you will probably at least get a better understanding of the process that\'s going on. I\'ve been using this method lately to great success!

回答14:

For Swift user with designable option:

1. Create a custom UIView subclass and a xib files, that we will name after our own class name: in our case MemeView. Inside the Meme View class remember to define it as designable with the @IBDesignable attribute before the class declaration

2. Rember to set the File’s Owner in the xib with our custom UIView subclass in Indetity Inspector panel

   

3. In the xib file now we can build our interface, make constraints, create outlets, actions etc.

4. We need to implement few methods to our custom class to open the xib once initialized

   class XibbedView: UIView {

   weak var nibView: UIView!
   
   override convenience init(frame: CGRect) {
       let nibName = NSStringFromClass(self.dynamicType).componentsSeparatedByString(\".\").last!
       self.init(nibName: nibName)
   }
   
   required init?(coder aDecoder: NSCoder) {
       super.init(coder: aDecoder)
       let nibName = NSStringFromClass(self.dynamicType).componentsSeparatedByString(\".\").last!
       let nib = loadNib(nibName)
       nib.frame = bounds
       nib.translatesAutoresizingMaskIntoConstraints = false
       addSubview(nib)
       nibView = nib
       setUpConstraints()
   }
   
   init(nibName: String) {
       super.init(frame: CGRectZero)
       let nibName = NSStringFromClass(self.dynamicType).componentsSeparatedByString(\".\").last!
       let nib = loadNib(nibName)
       nib.frame = bounds
       nib.translatesAutoresizingMaskIntoConstraints = false
       addSubview(nib)
       nibView = nib
       setUpConstraints()
   }
   
   func setUpConstraints() {
       [\"V\",\"H\"].forEach { (quote) -> () in
           let format = String(format:\"\\(quote):|[nibView]|\")
           addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(format, options: [], metrics: nil, views: [\"nibView\" : nibView]))
       }
   }
   
   func loadNib(name: String) -> UIView {
       let bundle = NSBundle(forClass: self.dynamicType)
       let nib = UINib(nibName: name, bundle: bundle)
       let view = nib.instantiateWithOwner(self, options: nil)[0] as! UIView
   
       return view
   }
   

   }

5. In our custom class we can also define some inspecatable properties to have full control over them from interface builder
   

   @IBDesignable class MemeView: XibbedView {

   @IBInspectable var memeImage: UIImage = UIImage() {
       didSet {
           imageView.image = memeImage
       }
   }
   @IBInspectable var textColor: UIColor = UIColor.whiteColor() {
       didSet {
           label.textColor = textColor
       }
   }
   @IBInspectable var text: String = \"\" {
       didSet {
           label.text = text
       }
   }
   @IBInspectable var roundedCorners: Bool = false {
       didSet {
           if roundedCorners {
               layer.cornerRadius = 20.0
               clipsToBounds = true
           }
           else {
               layer.cornerRadius = 0.0
               clipsToBounds = false
           }
       }
   }
   
   @IBOutlet weak var label: UILabel!
   @IBOutlet weak var imageView: UIImageView!
   

}

Few examples:

If we need to add more information the view while is displayed inside a storyboard or another xib, to do that we can implement prepareForInterfaceBuilder(), this method will be executed only while opening the file in interface builder. If you did everything I wrote but nothing is working, the is a way to debug a sigle view by adding breakpoints in its implementation.
Here is the views hierarchy.

Hope this helps a full sample can be downloaded here

回答15:

The previous answer does not take into account a change in the NIB (XIB) structure that occurred between 2.0 and 2.1 of the iPhone SDK. User contents now start at index 0 instead of 1.

You can use the 2.1 macro which is valid for all version 2.1 and above (that\'s two underscores before IPHONE:

 // Cited from previous example
 NSArray* nibViews =  [[NSBundle mainBundle] loadNibNamed:@\"QPickOneView\" owner:self options:nil];
 int startIndex;
 #ifdef __IPHONE_2_1
 startIndex = 0;
 #else
 startIndex = 1;
 #endif
 QPickOneView* myView = [ nibViews objectAtIndex: startIndex];
 myView.question = question;

We use a technique similar to this for most of our applications.

Barney

回答16:

I had reason to do the same thing (programmatically loading a view from a XIB file), but I needed to do this entirely from the context of a subclass of a subclass of a UIView (i.e. without involving the view controller in any way). To do this I created this utility method:

+ (id) initWithNibName:(NSString *)nibName withSelf:(id)myself {

    NSArray *bundle = [[NSBundle mainBundle] loadNibNamed:nibName
                                                    owner:myself options:nil];
    for (id object in bundle) {
        if ([object isKindOfClass:[myself class]]) {
            return object;
        }
    }  

    return nil;
} 

Then I call it from my subclass\' initWithFrame method like so:

- (id)initWithFrame:(CGRect)frame {

    self = [Utilities initWithNibName:@\"XIB1\" withSelf:self];
    if (self) {
        // Initialization code.
    }
    return self;
}

Posted for general interest; if anyone sees any problems without doing it this way, please let me know.

回答17:

Here\'s a way to do it in Swift (currently writing Swift 2.0 in XCode 7 beta 5).

From your UIView subclass that you set as \"Custom Class\" in the Interface Builder create a method like this (my subclass is called RecordingFooterView):

class func loadFromNib() -> RecordingFooterView? {
    let nib = UINib(nibName: \"RecordingFooterView\", bundle: nil)
    let nibObjects = nib.instantiateWithOwner(nil, options: nil)
    if nibObjects.count > 0 {
        let topObject = nibObjects[0]
        return topObject as? RecordingFooterView
    }
    return nil
}

Then you can just call it like this:

let recordingFooterView = RecordingFooterView.loadFromNib()

回答18:

None of the answers explain how to create the stand alone XIB that is the root of this question. There is no Xcode 4 option to \"Create New XIB File\".

To do this

1) Choose \"New File...\"
2) Choose the \"User Interface\" category under the iOS section
3) Choose the \"View\" item
4) You will then be prompted to choose an iPhone or iPad format

This may seem simple but it can save you a few minutes poking around for it since the word \"XIB\" does not appear anywhere.

回答19:

@AVeryDev

6) To attach the loaded view to your view controller\'s view:

[self.view addSubview:myViewFromNib];

Presumably, it is necessary to remove it from the view to avoid memory leaks.

To clarify: the view controller has several IBOutlets, some of which are connected to items in the original nib file (as usual), and some are connected to items in the loaded nib. Both nib\'s have the same owner class. The loaded view overlays the original one.

Hint: set the opacity of the main view in the loaded nib to zero, then it won\'t obscure the items from the original nib.

回答20:

After spending many hours, I forged out following solution. Follow these steps to create custom UIView.

1) Create class myCustomView inherited from UIView.

2) Create .xib with name myCustomView.

3) Change Class of UIView inside your .xib file, assign myCustomView Class there.

4) Create IBOutlets

5) Load .xib in myCustomView * customView. Use following sample code.

myCustomView * myView = [[[NSBundle mainBundle] loadNibNamed:@\"myCustomView\" owner:self options:nil] objectAtIndex:0];
[myView.description setText:@\"description\"];

Note: For those who still face issue can comment, I will provide them link of sample project with myCustomView

回答21:

Shortest version:

RSFavoritePlaceholderView *favoritePlaceholderView = [[[NSBundle mainBundle] loadNibNamed:@\"RSFavoritePlaceholderView\" owner:self options:nil] firstObject];

回答22:

I have a convention of naming xibs with views in them the same as the view. Same as one would do for a view controller. Then, I don\'t have to write out class names in code. I load a UIView from a nib file with the same name.

Example for a class called MyView.

• Create a nib file called MyView.xib in Interface Builder
• In Interface Builder, add a UIView. Set its class to MyView. Customize to your heart\'s content, wire up instance variables of MyView to subviews you might want to access later.

• In your code, create a new MyView like this:

  MyView *myView = [MyView nib_viewFromNibWithOwner:owner];

Here\'s the category for this:

@implementation UIView (nib)

+ (id) nib_viewFromNib {
    return [self nib_viewFromNibWithOwner:nil];
}

+ (id) nib_viewFromNibWithOwner:(id)owner {
    NSString *className = NSStringFromClass([self class]);
    NSArray *nib = [[NSBundle mainBundle] loadNibNamed:className owner:owner options:nil];
    UIView *view = nil;
    for(UIView *v in nib) {
        if ([v isKindOfClass:[self class]]) {
            view = v;
            break;
        }
    }
    assert(view != nil && \"View for class not found in nib file\");
    [view nib_viewDidLoad];
    return view;
}

// override this to do custom setup
-(void)nib_viewDidLoad {

}

I\'d then wire up buttons with actions from the controller I am using, and set things on labels using the outlets in my custom view subclass.

回答23:

To programmatically load a view from a nib/xib in Swift 4:

// Load a view from a Nib given a placeholder view subclass
//      Placeholder is an instance of the view to load.  Placeholder is discarded.
//      If no name is provided, the Nib name is the same as the subclass type name
//
public func loadViewFromNib<T>(placeholder placeholderView: T, name givenNibName: String? = nil) -> T {

    let nib = loadNib(givenNibName, placeholder: placeholderView)
    return instantiateView(fromNib: nib, placeholder: placeholderView)
}

// Step 1: Returns a Nib
//
public func loadNib<T>(_ givenNibName: String? = nil, placeholder placeholderView: T) -> UINib {
    //1. Load and unarchive nib file
    let nibName = givenNibName ?? String(describing: type(of: placeholderView))

    let nib = UINib(nibName: nibName, bundle: Bundle.main)
    return nib
}

// Step 2: Instantiate a view given a nib
//
public func instantiateView<T>(fromNib nib: UINib, placeholder placeholderView: T) -> T {
    //1. Get top level objects
    let topLevelObjects = nib.instantiate(withOwner: placeholderView, options: nil)

    //2. Have at least one top level object
    guard let firstObject = topLevelObjects.first else {
        fatalError(\"\\(#function): no top level objects in nib\")
    }

    //3. Return instantiated view, placeholderView is not used
    let instantiatedView = firstObject as! T
    return instantiatedView
}

回答24:

I ended up adding a category to UIView for this:

 #import \"UIViewNibLoading.h\"

 @implementation UIView (UIViewNibLoading)

 + (id) loadNibNamed:(NSString *) nibName {
    return [UIView loadNibNamed:nibName fromBundle:[NSBundle mainBundle] retainingObjectWithTag:1];
 }

 + (id) loadNibNamed:(NSString *) nibName fromBundle:(NSBundle *) bundle retainingObjectWithTag:(NSUInteger) tag {
    NSArray * nib = [bundle loadNibNamed:nibName owner:nil options:nil];
    if(!nib) return nil;
    UIView * target = nil;
    for(UIView * view in nib) {
        if(view.tag == tag) {
            target = [view retain];
            break;
        }
    }
    if(target && [target respondsToSelector:@selector(viewDidLoad)]) {
        [target performSelector:@selector(viewDidLoad)];
    }
    return [target autorelease];
 }

 @end

explanation here: viewcontroller is less view loading in ios&mac