Interface Builder文件中的未知类PageContentViewController

Question

应用程序构建成功，但是当我开始运行应用程序时，程序停止并显示此错误

PageViewDemo[1355:8607] Unknown class PageContentViewController in Interface Builder file.
［UIViewController setImageFile:]: unrecognized selector sent to instance, 

界面是：

#import <UIKit/UIKit.h>
@interface PageContentViewController:UIViewController
@property (strong, nonatomic) IBOutlet UIImageView *backgroundImageView;
@property (strong, nonatomic) IBOutlet UILabel *titleLabel;
@property NSUInteger pageIndex;
@property NSString *titleText;
@property NSString *imageFile;
@end