Question

在HDScrollview.h中定义了UIImageView类别。它未在GoodDetailViewController.m中导入，但当代码cell = [[[NSBundle mainBundle] loadNibNamed: CellIdentifier owner: self options: nil] lastObject];运行时，-(id)initWithCoder:(NSCoder *)aDecoder中的HDScrollview.m将被调用。这里发生了什么？任何帮助将不胜感激。

PS。

HDScrollview.h已导入GoodDetailViewController.m但未导入GoodDetailViewController.h

GoodsListViewController.m

...
#import "GoodDetailViewController.h"
...

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row == _mutableArrayGoods.count) {
        return [self setLoadMoreCell];
    }

    static NSString *CellIdentifier = @"TableViewCellGoods";
    TableViewCellGoods *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
        cell = [[[NSBundle mainBundle] loadNibNamed: CellIdentifier owner: self options: nil] lastObject];
        [cell initGoodsCellDefaultStyle];
    }

    // Configure the cell...
    if ( indexPath.row < _mutableArrayGoods.count ) {
        Good *good = [_mutableArrayGoods objectAtIndex: indexPath.row];
        cell.good = good;
        cell.delegate = self;
    }

    return cell;
}

HDScrollview.h

#import <UIKit/UIKit.h>
#import "HdPageControl.h"
@protocol HDScrollviewDelegate <NSObject>
-(void)TapView:(int)index;
@end

@interface HDScrollview : UIScrollView<UIScrollViewDelegate>

@property (nonatomic,strong) HdPageControl *pagecontrol;
@property (nonatomic,assign) NSInteger currentPageIndex;
@property (assign,nonatomic) id<HDScrollviewDelegate> HDdelegate;

-(id)initWithFrame:(CGRect)frame withImageView:(NSMutableArray *)imageview;

-(id)initLoopScrollWithFrame:(CGRect)frame withImageView:(NSMutableArray *)imageview;
-(void)HDscrollViewDidScroll;
-(void)HDscrollViewDidEndDecelerating;
@end

@interface UIImageView (CopyImageview)<NSCoding>
@end

HDScrollview.m

...

@implementation UIImageView (CopyImageview)
-(void)encodeWithCoder:(NSCoder *)aCoder
{

    [aCoder encodeObject:self.backgroundColor forKey:@"backgroundColor"];
    [aCoder encodeObject:self.image forKey:@"image"];
    [aCoder encodeInt:self.contentMode forKey:@"contentMode"];
    [aCoder encodeInt:self.subviews.count forKey:@"subviewscount"];
    for(int i=0;i<self.subviews.count;i++)
    {
        UIView *view=self.subviews[i];
        [aCoder encodeObject:view forKey:[NSString stringWithFormat:@"view%d",i]];
    }
}
-(id)initWithCoder:(NSCoder *)aDecoder
{
    if (self=[super init]) {
        self.backgroundColor=[aDecoder decodeObjectForKey:@"backgroundColor"];
        self.image=[aDecoder decodeObjectForKey:@"image"];
        self.contentMode=[aDecoder decodeIntForKey:@"contentMode"];
        int subviewscount=[aDecoder decodeIntForKey:@"subviewscount"];
        for(int i=0;i<subviewscount;i++)
        {
           UIView* view=[aDecoder decodeObjectForKey:[NSString stringWithFormat:@"view%d",i]];
            [self addSubview:view];
        }
    }
    return self;
}
@end

...

Answer 1

当您从Nib文件实例化视图对象时，iOS将使用nib文件的XML详细信息，并将从中创建解码器。然后，它将调用视图的initWithCoder:方法，以便您的视图可以使用解码器信息初始化其状态和属性。

Answer 2

除非要在类别中添加新方法并在控制器中使用它，否则不需要显式导入类别（因为编译器知道方法可用，所以需要导入）。在这里发生的事情是你的Xib可能包含UIImageView，而Xib被加载时会创建图像视图，这将导致initWithCoder被调用，因为对象是从Xib实例化的（这是对于从Xib实例化的所有对象都是通用的。没有魔法在这里发生

initWithCoder：在不导入类别的情况下调用

2 个答案: