最短的版本:

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

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;
}

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
}

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

还有一种更简单的方法来访问视图，而不是将nib作为数组处理。

1)创建一个自定义的View子类，其中包含你以后想要访问的任何出口。——MyView

2)在你想要加载和处理nib的UIViewController中，创建一个IBOutlet属性来保存加载的nib的视图

在MyViewController中(一个UIViewController子类)

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

(别忘了合成它并在你的。m文件中发布它)

3)在IB中打开你的nib(我们称之为'myViewNib.xib')，设置你文件的所有者为MyViewController

4)现在连接你的文件的所有者出口myViewFromNib到nib的主视图。

5)现在在MyViewController中，写以下一行:

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

当你这样做的时候，把你的财产称为“自我”。myViewFromNib”将让你从你的nib访问视图!

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.