ios - 如何在 Objective-C 中复制自定义对象？

Question

我有两个数组。首先包含自定义对象。现在我想将第一个数组的所有对象复制到另一个数组中。为此，我使用以下代码。

数组。

arr_post=[[NSMutableArray alloc]init];
copy_arr_user_post=[[NSMutableArray alloc]init];

我正在像这样将对象添加到其中。

for(i=0;i<[arr_main count];i++)
{
    Post *obj=[[Post alloc]init];
    obj.name=@"abc";
    obj.category=@"social";
   [arr_post addObject:obj];


}

现在我正在像这样复制到另一个数组

 [arr_post addObject:user_post];
 Post *objectCopy = [user_post copy]; //create a copy of our object
 [copy_arr_user_post addObject: objectCopy]; //insert copy into other array

在 Post.h 中

@interface Post : NSObject<NSCopying>

在 Post.m 中

- (id)copyWithZone:(NSZone *)zone
{
    // Copying code here.
    Post *another =[[[self class] allocWithZone:zone] init];
    another.id=self.id;
    another.category=self.category;
    return another;
}

但它不会复制我得到空值的对象。为什么？

Answer 1

我发现一种比 NSCopyng 更快的方法

-用这两个方法创建一个NSObject类

#import <objc/runtime.h>
-(id)deepCopy
{
NSArray *tmpArray = @[self];
NSData *buffer = [NSKeyedArchiver archivedDataWithRootObject:tmpArray];
return [NSKeyedUnarchiver unarchiveObjectWithData:buffer][0];
}

- (NSMutableArray *)allProperties
{
    NSMutableArray *props = [NSMutableArray array];
    unsigned int outCount, i;
    objc_property_t *properties = class_copyPropertyList([self class], &outCount);
    for (i = 0; i < outCount; i++) {
        objc_property_t property = properties[i];

        //Excluding all readOnly properties
        unsigned int numOfAttributes;
        objc_property_attribute_t *propertyAttributes = property_copyAttributeList(property, &numOfAttributes);

        BOOL foundReadonly = NO;

        for ( unsigned int ai = 0; ai < numOfAttributes; ai++ )
        {
            switch (propertyAttributes[ai].name[0]) {
                case 'T': // type
                    break;
                case 'R': // readonly
                    foundReadonly = YES;
                    break;
                case 'C': // copy
                    break;
                case '&': // retain
                    break;
                case 'N': // nonatomic
                    break;
                case 'G': // custom getter
                    break;
                case 'S': // custom setter
                    break;
                case 'D': // dynamic
                    break;
                default:
                    break;
            }
        }
        free(propertyAttributes);

        if (!foundReadonly)
        {
            NSString *propertyName = [[NSString alloc] initWithCString:property_getName(property) encoding:NSASCIIStringEncoding];
            [props addObject:propertyName];
        }
    }
    free(properties);
    return props;
}

-让你的对象符合NSCoding

#pragma mark - NSCoding
- (instancetype)initWithCoder:(NSCoder *)decoder {
    self = [super init];
    if (self)
    {
        NSArray *keys = [self allProperties];

        for (NSString *key in keys)
        {
            [self setValue:[decoder decodeObjectForKey:key] forKey:key] ;
        }

    }
    return self;
}
- (void)encodeWithCoder:(NSCoder *)aCoder
{
    NSArray *keys = [self allProperties];

    for (NSString *key in keys)
    {
        [aCoder encodeObject:[self valueForKey:key] forKey:key];
    }
}

-导入类别

现在你可以复制任何类型的对象了

MYObject *copy = [originalObject deepCopy];
NSArray *arrayWithCopiedObjects = [originalArray deepCopy];

等....