递归遍历未知结构的NSDictionary

Question

有没有人对未知结构的 NSDictionary 进行递归有序遍历？我想采用任何 NSDictionary 并按层次顺序处理每个级别。

1) 此数据来自经过验证的 JSON。是否可以肯定地说，从 SBJSON（JSON 框架）等框架创建的 NSDictionary 只会产生嵌套字典、数组和任意叶子的组合？

2) 如何使用适用于数组和字典的快速枚举来完成通用遍历？使用下面的代码，一旦我到达数组中的字典，它就会停止遍历。但是，如果我在数组条件中继续递归（以检查数组中的字典），它会在id value = [dict valueForKey:key]; 的下一次迭代中使用-[__NSCFDictionary length]: unrecognized selector sent to instance SIGABRT。我不知道为什么这会是个问题，因为我已经通过顶级字典（在其中找到子级字典数组）超过了那条线。

-(void)processParsedObject:(id)dict counter:(int)i parent:(NSString *)parent
{
    for (id key in dict) {
        id value = [dict valueForKey:key];
        NSLog(@"%i : %@ : %@ -> %@", i, [value class], parent, key);

        if ([value isKindOfClass:[NSDictionary class]])
        {
            i++;
            NSDictionary* newDict = (NSDictionary*)value;
            [self processParsedObject:newDict counter:i parent:(NSString*)key];
            i--;
        }
        else if ([value isKindOfClass:[NSArray class]])
        {
            for (id obj in value) {
                NSLog(@"Obj Type: %@", [obj class]);
            }
        }
    }
}

非常感谢

Answer 1

我做过类似的事情，我会遍历来自 Web 服务的 JSON 结构化对象并将每个元素转换为可变版本。

- (void)processParsedObject:(id)object
{
    [self processParsedObject:object depth:0 parent:nil];
}

- (void)processParsedObject:(id)object depth:(int)depth parent:(id)parent
{      
    if ([object isKindOfClass:[NSDictionary class]])
    {
        for (NSString* key in [object allKeys])
        {
            id child = [object objectForKey:key];
            [self processParsedObject:child depth:(depth + 1) parent:object];
        }
    }
    else if ([object isKindOfClass:[NSArray class]])
    {
        for (id child in object)
        {
            [self processParsedObject:child depth:(depth + 1) parent:object];
        }   
    }
    else
    {
        // This object is not a container you might be interested in it's value
        NSLog(@"Node: %@  depth: %d", [object description], depth);
    }
}

Answer 2

我需要知道值的键名，所以我重写了 Joel 的内容并想出了这个：

- (void)enumerateJSONToFindKeys:(id)object forKeyNamed:(NSString *)keyName
{
    if ([object isKindOfClass:[NSDictionary class]])
    {
        // If it's a dictionary, enumerate it and pass in each key value to check
        [object enumerateKeysAndObjectsUsingBlock:^(id key, id value, BOOL *stop) {
            [self enumerateJSONToFindKeys:value forKeyNamed:key];
        }];
    }
    else if ([object isKindOfClass:[NSArray class]])
    {
        // If it's an array, pass in the objects of the array to check
        [object enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
            [self enumerateJSONToFindKeys:obj forKeyNamed:nil];
        }];
    }
    else
    {
        // If we got here (i.e. it's not a dictionary or array) so its a key/value that we needed 
        NSLog(@"We found key %@ with value %@", keyName, object);
    }
}

然后你会这样称呼它：

[self enumerateJSONToFindKeys:JSON forKeyNamed:nil];

---

或者，如果您想让给定的键路径可变（这样您可以使用setValue:forKeyPath: 回写它），您可以执行以下操作：

- (void)makeDictionariesMutableForKeyPath:(NSString *)keyPath {
    NSArray *keys = [keyPath componentsSeparatedByString:@"."];

    NSString *currentKeyPath = nil;
    for (NSString *key in keys) {
        if (currentKeyPath) {
            NSString *nextKeyPathAddition = [NSString stringWithFormat:@".%@", key];
            currentKeyPath = [currentKeyPath stringByAppendingString:nextKeyPathAddition];
        } else {
            currentKeyPath = key;
        }

        id value = [self.mutableDictionary valueForKeyPath:currentKeyPath];
        if ([value isKindOfClass:NSDictionary.class]) {
            NSMutableDictionary *mutableCopy = [(NSDictionary *)value mutableCopy];
            [self.mutableDictionary setValue:mutableCopy forKeyPath:currentKeyPath];
        }
    }

}