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

我最终为这个添加了一个类别到UIView:

 #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

这里的解释:在ios和mac中viewcontroller是更少的视图加载

@AVeryDev

6)将加载的视图附加到视图控制器的视图:

[self.view addSubview:myViewFromNib];

据推测，有必要将其从视图中删除以避免内存泄漏。

澄清一下:视图控制器有几个iboutlet，其中一些连接到原始nib文件中的项(像往常一样)，一些连接到加载的nib中的项。两个nib都有相同的所有者类。加载的视图覆盖了原始视图。

提示:在加载的笔尖中设置主视图的不透明度为零，那么它将不会从原始笔尖中模糊项目。

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
}

我有一种命名xib的约定，其中的视图与视图相同。和视图控制器一样。这样，我就不必在代码中写出类名了。我从同名的nib文件中加载一个UIView。

一个名为MyView的类的例子。

创建一个名为MyView的nib文件。接口生成器中的xib 在Interface Builder中添加一个UIView。将其类设置为MyView。自定义到你的内心的内容，连接MyView的实例变量到子视图，你可能想以后访问。 在你的代码中，像这样创建一个新的MyView: MyView * MyView = [MyView nib_viewfromnibwiowner:owner];

这是它的分类:

@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 {

}

然后，我将连接按钮与我正在使用的控制器的动作，并使用自定义视图子类中的outlet在标签上设置内容。

我发现Aaron Hillegass(作者，讲师，可可忍者)的这篇博客非常有启发性。即使您不采用他修改后的方法通过指定的初始化器加载NIB文件，您也至少可以更好地理解正在进行的过程。我最近一直在用这个方法，而且非常成功!