前面的答案没有考虑iPhone SDK 2.0到2.1之间发生的NIB (XIB)结构的变化。用户内容现在从索引0开始，而不是1。

你可以使用2.1宏，它适用于所有2.1及以上版本(在IPHONE前面加两个下划线):

 // 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;

我们在大多数应用程序中都使用类似的技术。

巴尼

你不应该在Interface Builder中将视图控制器的类设置为UIView的子类。这肯定是你的部分问题。保留它为UIViewController，它的子类，或者其他自定义类。

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.

我也想做一些类似的事情，这是我发现的: (SDK 3.1.3)

我有一个视图控制器a(本身由一个导航控制器拥有)，它在一个按钮按下加载VC B:

在AViewController.m

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

现在VC B有它的接口从Bnib，但当一个按钮被按下，我想去一个“编辑模式”有一个独立的UI从不同的nib，但我不想要一个新的VC的编辑模式，我想新的nib与我现有的B VC相关联。

在BViewController中。M(按按钮方式)

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

然后按下另一个按钮(退出编辑模式):

[editView removeFromSuperview];

我又变回了原来的Bnib

这很好，但请注意我的EditMode。nib中只有一个顶级obj，一个UIView obj。 不管这个nib中的文件所有者是设置为BViewController还是默认的NSObject，但要确保文件所有者中的视图出口没有设置为任何东西。 如果是，那么我得到一个exc_bad_access崩溃，xcode继续加载6677个堆栈帧 显示一个内部UIView方法被反复调用…看起来像一个无限循环。 (视图出口是设置在我原来的Bnib然而)

希望这能有所帮助。

这是一件应该比较容易的事情。我最终扩展了UIViewController并添加了一个loadNib:inPlaceholder: selector。现在我可以说

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

下面是这个类别的代码(它和Gonso描述的一样):

@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

在Swift 4中以编程方式从nib/xib加载视图:

// 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
}

我做了一个我喜欢的分类:

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

然后，像这样调用:

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

如果你的nib不是你的类名，请使用一个nib名。

为了在你的子类中覆盖它以获得额外的行为，它可以看起来像这样:

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