从Xib文件加载UIView的5种方式

// Instantiate the nib content without any reference to it.
NSArray *nibContents = [[NSBundle mainBundle] loadNibNamed:@"EPPZPlainView" owner:nil options:nil];
 
// Find the view among nib contents (not too hard assuming there is only one view in it).
UIView *plainView = [nibContents lastObject];
 
// Some hardcoded layout.
CGSize padding = (CGSize){ 22.0, 22.0 };
plainView.frame = (CGRect){padding.width, padding.height, plainView.frame.size};
 
// Add to the view hierarchy (thus retain).
[self.view addSubview:plainView];

@interface EPPZViewController ()
 
// Define an outlet for the custom view.
@property (nonatomic, weak) IBOutlet UIView *referencedView;
// An action that triggers showing the view.
-(IBAction)showReferencedView;
 
@end
 
@implementation EPPZViewController
 
-(IBAction)showReferencedView
{
    // Instantiate a referenced view (assuming outlet has hooked up in XIB).
    [[NSBundle mainBundle] loadNibNamed:@"EPPZReferencedView" owner:self options:nil];
 
    // Controller‘s outlet has been bound during nib loading, so we can access view trough the outlet.
    [self.view addSubview:self.referencedView];
}
 
@end

注意，不要把视图控制器跟包裹视图（相当于视图根容器）连起来（即使你觉得这样是对的，也不要这么做）。因为那会重新分配控制器的视图在实例化这个空视图的时候。

这种方式通过添加一个UITableViewCell到xib文件，也适用于UITableViewCell实例方法（不需要包裹视图）. 不过这个不在本次的讨论范围之内了。

@interface EPPZViewController ()
 
@property (nonatomic, weak) IBOutlet UIView *referencedView;
-(IBAction)showConnectedActionsView;
-(IBAction)connectedActionsViewTouchedUp:(UIButton*) button;
 
@end
 
@implementation EPPZViewController
 
-(IBAction)showConnectedActionsView
{
    // Instantiate a referenced view (assuming outlet has hooked up in XIB).
    [[NSBundle mainBundle] loadNibNamed:@"EPPZConnectedActionsView" owner:self options:nil];
 
    // Controller‘s outlet has been bound during nib loading, so we can access view trough the outlet.
    [self.view addSubview:self.referencedView];
}
 
-(IBAction)connectedActionsViewTouchedUp:(UIButton*) button
{
    // Any interaction (I simply remove the custom view here).
    [button.superview removeFromSuperview];
}
 
@end

@class EPPZSubclassedView;
@interface EPPZSubclassedViewOwner : NSObject
@property (nonatomic, weak) IBOutlet EPPZSubclassedView *subclassedView;
@end
 
@interface EPPZSubclassedView : UIView
+(void)presentInViewController:(UIViewController*) viewController;
-(IBAction)dismiss;
@end

@implementation EPPZSubclassedViewOwner
@end
 
@implementation EPPZSubclassedView
 
+(void)presentInViewController:(UIViewController*) viewController
{
    // Instantiating encapsulated here.
    EPPZSubclassedViewOwner *owner = [EPPZSubclassedViewOwner new];
    [[NSBundle mainBundle] loadNibNamed:NSStringFromClass(self) owner:owner options:nil];
 
    // Add to the view hierarchy (thus retain).
    [viewController.view addSubview:owner.subclassedView];
}
 
-(IBAction)dismiss
{ [self removeFromSuperview]; }
 
@end

@interface EPPZViewController
-(IBAction)showSubclassedView;
@end
 
@implementation EPPZViewController
 
-(IBAction)showSubclassedView
{
    // A tiny one-liner that has anything to do with the custom view.
    [EPPZSubclassedView presentInViewController:self];
}
 
@end

@class EPPZDecoupledView;
@interface EPPZDecoupledViewOwner : NSObject
@property (nonatomic, weak) IBOutlet EPPZDecoupledView *decoupledView;
@end
 
@protocol EPPZDecoupledViewDelegate
-(void)decoupledViewTouchedUp:(EPPZDecoupledView*) decoupledView;
-(void)decoupledViewDidDismiss:(EPPZDecoupledView*) decoupledView;
@end
 
@interface EPPZDecoupledView : UIView
// Indicate that this view should be presented only controllers those implements the delegate methods.
+(void)presentInViewController:(UIViewController<EPPZDecoupledViewDelegate>*) viewController;
-(IBAction)viewTouchedUp;
-(IBAction)dismiss;
@end

@implementation EPPZDecoupledViewOwner
@end
 
@interface EPPZDecoupledView ()
@property (nonatomic, weak) UIViewController <EPPZDecoupledViewDelegate> *delegateViewController;
@end
 
@implementation EPPZDecoupledView
 
+(void)presentInViewController:(UIViewController<EPPZDecoupledViewDelegate>*) viewController
{
    // Instantiating encapsulated here.
    EPPZDecoupledViewOwner *owner = [EPPZDecoupledViewOwner new];
    [[NSBundle mainBundle] loadNibNamed:NSStringFromClass(self) owner:owner options:nil];
 
    // Pass in a reference of the viewController.
    owner.decoupledView.delegateViewController = viewController;
 
    // Add (thus retain).
    [viewController.view addSubview:owner.decoupledView];
}
 
-(IBAction)viewTouchedUp
{
    // Forward to delegate.
    [self.delegateViewController decoupledViewTouchedUp:self];
}
 
-(IBAction)dismiss
{
    [self removeFromSuperview];
 
    // Forward to delegate.
    [self.delegateViewController decoupledViewDidDismiss:self];
}
 
@end

@class EPPZDecoupledView;
@protocol EPPZDecoupledViewDelegate
-(void)decoupledViewTouchedUp:(EPPZDecoupledView*) decoupledView;
-(void)decoupledViewDidDismiss:(EPPZDecoupledView*) decoupledView;
@end
 
@interface EPPZDecoupledView : UIView
+(void)presentInViewController:(UIViewController<EPPZDecoupledViewDelegate>*) viewController;
@end

@interface EPPZViewController () <EPPZDecoupledViewDelegate>
-(IBAction)showDecoupledView;
@end
 
@implementation EPPZViewController
 
-(IBAction)showDecoupledView
{ [EPPZDecoupledView presentInViewController:self]; }
 
-(void)decoupledViewTouchedUp:(EPPZDecoupledView*) decoupledView
{ /* Whatever feature. */ }
 
-(void)decoupledViewDidDismiss:(EPPZDecoupledView*) decoupledView
{ /* Acknowledge sadly. */ }
 
@end