关于model类归档与反归档

作者: iOS程序员asdf | 来源:发表于2017-02-06 17:41 被阅读0次

接到新需求要把整个页面缓存下来,在没有网络的情况下还能显示上次的页面,值得庆幸的是当初写的时候就都是用的model来存储的数据,我马上就想到用归档与反归档,更值得庆幸的是我的model有个baseModel,只要在baseModel中实现以下两个方法就可以了:

- (void)encodeWithCoder:(NSCoder *)aCoder;
- (id)initWithCoder:(NSCoder *)aDecoder;

可是如果在基类中你是不知道具体子类的属性的,这样就需要用到iOS中我认为最强大的runtime了。
废话不多说,直接上代码:

#pragma mark 归档
- (void)encodeWithCoder:(NSCoder *)aCoder {
    Class currentClass = self.class;
    if (currentClass == NSObject.class) {
        return;
    }
    while (currentClass && currentClass != [NSObject class])
    {
        unsigned int count = 0;
        objc_property_t *pList = class_copyPropertyList(currentClass, &count);
        if (count>0) {
            for (int i=0;i<count;i++) {
                NSString *key = [NSString stringWithUTF8String:property_getName(pList[i])];
                [aCoder encodeObject: [self valueForKey:key] forKey:key];
            }
        }
        currentClass = class_getSuperclass(currentClass);
        free(pList);
    }
}

- (id)initWithCoder:(NSCoder *)aDecoder {
    Class currentClass = self.class;
    if (currentClass == NSObject.class) {
        return nil;
    }
    while (currentClass && currentClass != [NSObject class])
    {
        unsigned int count = 0;
        objc_property_t *pList = class_copyPropertyList(currentClass, &count);
        if (count > 0) {
            for (int i = 0;i < count;i++) {
                NSString *key = [NSString stringWithUTF8String:property_getName(pList[i])];
                [self setValue:[aDecoder  decodeObjectForKey:key] forKey:key];
            }
        }
        currentClass = class_getSuperclass(currentClass);
        free(pList);
    }
    return  self;
}

稍微讲解一下代码。

objc_property_t *pList = class_copyPropertyList(currentClass, &count);
这句代码是为了拿到本类中的所有属性,其中count代表的是属性的个数。

for (int i=0;i<count;i++) {
NSString *key = [NSString stringWithUTF8String:property_getName(pList[i])];
[aCoder encodeObject: [self valueForKey:key] forKey:key];
}
这一段就是把每一个属性都encoding了。

currentClass = class_getSuperclass(currentClass);
这句是防止父类中有属性没有encoding,所以用了一个while循环。

这样你只需要在用的时候直接archived一下,转换成NSData类型的,这样就可以放到数组中,直接write到本地,用的时候直接unarchived一下就好了。
附上使用的代码:

- (void)writePointWithArray:(NSArray *)array {
    NSMutableArray *localArray = [NSMutableArray arrayWithCapacity:array.count];
    for (LYNewsModel *model in array) {
        NSData *data = [NSKeyedArchiver archivedDataWithRootObject:model];
        [localArray addObject:data];
    }
    [localArray writeToFile:kPointPath atomically:YES];
}
- (NSArray *)getPoints {
    NSMutableArray *array = [NSMutableArray array];
    NSArray *localArray = [NSArray arrayWithContentsOfFile:kPointPath];
    for (NSData *data in localArray) {
        LYNewsModel *model = [NSKeyedUnarchiver unarchiveObjectWithData:data];
        [array addObject:model];
    }
    return array;
}

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