类 超类 子类

Question

我正在尝试将两个子类设为一个类：

// Old code

- (void)setPaging {
    [pagingScrollView addSubview:self.ImageScrollView];
}

@interface ImageScrollView : UIScrollView <UIScrollViewDelegate> {
    UIView        *imageView;
    NSUInteger     index;
}
@property (assign) NSUInteger index;
- (void)displayTiledImageNamed:(CGPDFPageRef)page size:(CGSize)imageSize;
@end

@implementation ImageScrollView
@synthesize index;
// ... my methods ...
@end

改为：

// NEW Code__________________________________________________________*

- (void)setPaging {
    if (D == 1) {
        // error: request for member 'ISVportrate' in something not a
        // structure or union
        [pagingScrollView addSubview:self.ISVportrate];
    } else if (D == 2) {
        //error: request for member 'ISVLandscape' in something not a
        // structure or union
        [pagingScrollView addSubview:self.ISVLandscape];
    }
}

@class ISVportrate;
@class ISVLandscape;
@interface ImageScrollView : UIScrollView <UIScrollViewDelegate> {
    UIView        *imageView;
    NSUInteger     index;
}
@property (assign) NSUInteger index;
- (void)displayTiledImageNamed:(CGPDFPageRef)page size:(CGSize)imageSize;
@end
@interface ISVportrate : ImageScrollView {}
@end
@interface ISVLandscape : ImageScrollView {}
@end

@implementation ISVportrate : ImageScrollView

// error: property 'index' attempting to use ivar 'index' declared in
// super class of 'ISVportrate'
@synthesize index;

// ... my methods ...
@end
@implementation ISVLandscape : ImageScrollView

// error: property 'index' attempting to use ivar 'index' declared in
// super class of 'ISVLandscape'
@synthesize index;

// ... my methods ...
@end

我做的不对，是吗？见上面我有4个错误……这是我第一次上课……帮助我理解，我想我几乎做对了。

Answer 1

@synthesize 在ImageScrollView 的@implementation 中，而不是在子类中。

self.ISVportrate 没有意义（除非你有一个名为-ISVportrate 的方法，这也没有意义）。

听起来您还没有完全了解面向对象的编程。您可能希望创建一个子类的适当实例并将其分配为包含它的任何视图的子视图....