iphone - UIKit中的类如何实现深拷贝？

Question

我有一个对象 imageView1。我想创建另一个对象来保留 imageView1 的深拷贝。像这样，

UIImageView *imageView1 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"background.png"]];
UIImageView *imageView2 = [imageView1 copy];

我知道它不起作用，因为 UIImageView 不符合 NSCopying。但应该如何 我愿意吗？

Answer 1

要创建 UIImageView 对象的深拷贝，您需要使用 NSKeyedArchiver 将其归档，然后使用 NSKeyedUnarchiver 将其取消归档，但这种方法存在一个问题，因为 UIImage 不符合 NSCoding 协议(protocol)。您首先需要做的是扩展 UIImage 类以支持 NSCoding。

在 UIImage 上添加一个名称为 NSCoding 的新类别，并放置以下代码:

UIImage+NSCoder.h

#import <UIKit/UIKit.h>

@interface UIImage (NSCoding)
- (id)initWithCoder:(NSCoder *)decoder;
- (void)encodeWithCoder:(NSCoder *)encoder;
@end

UIImage+NSCoder.m

#import "UIImage+NSCoder.h"

@implementation UIImage (NSCoding)
- (id)initWithCoder:(NSCoder *)decoder {
    NSData *pngData = [decoder decodeObjectForKey:@"PNGRepresentation"];
    [self autorelease];
    self = [[UIImage alloc] initWithData:pngData];
    return self;
}
- (void)encodeWithCoder:(NSCoder *)encoder {
    [encoder encodeObject:UIImagePNGRepresentation(self) forKey:@"PNGRepresentation"];
}

@end

然后在 UIImageView 上添加一个名为 DeepCopy 的新类别(例如)和以下代码:

UIImageView+DeepCopy.h

#import <UIKit/UIKit.h>

@interface UIImageView (DeepCopy)
-(UIImageView *)deepCopy;
@end

UIImageView+DeepCopy.m

#import "UIImageView+DeepCopy.h"
#import "UIImage+NSCoder.h"

@implementation UIImageView (DeepCopy)

-(UIImageView *)deepCopy
{
    NSMutableData *data = [[NSMutableData alloc] init];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    [archiver encodeObject:self forKey:@"imageViewDeepCopy"];
    [archiver finishEncoding];
    [archiver release];

    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    UIImageView *imgView = [unarchiver decodeObjectForKey:@"imageViewDeepCopy"];
    [unarchiver release];
    [data release];

    return imgView;
}

@end

用法:导入你的 UIImageView+DeepCopy.h

UIImageView *imgView1 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"picture.jpg"]];
UIImageView *imageView2 = [imgView1 deepCopy];