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

更改为：

// 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

我做得不对，对吗？看到上面我有 4 个错误…这是我第一次上课…帮助我理解，我想我几乎已经做对了。

Answer 1

@synthesize 位于 ImageScrollView 的 @implementation 中，而不是位于子类中。

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

听起来您还没有完全理解面向对象编程。您可能想要创建一个子类的适当实例，并将其指定为包含它的任何视图的子视图......