ios - 使用 swift 从 JSON 检索数据时出现问题

Question

我正在使用 swift 从 JSON 中检索数据。我是 JSON 的新手。我不知道如何检索这个嵌套值。我的 JSON 格式如下。

//JSON DATA
{
    "data": [
        {
            "category_id": 1,
            "category_name": "category1",
            "category_icon": "",
            "category_child": [
                {
                    "sub_category_id": 11,
                    "sub_category_name": "subcategoryname1",
                    "sub_category_icon": ""
                },
                {
                    "sub_category_id": 12,
                    "sub_category_name": "subcategoryname2",
                    "sub_category_icon": ""
                }
            ]
        },
        {
            "category_id": 2,
            "category_name": "category2",
            "category_icon": "",
            "category_child": [
                {
                    "sub_category_id": 21,
                    "sub_category_name": "subcategoryname12",
                    "sub_category_icon": ""
                },
                {
                    "sub_category_id": 22,
                    "sub_category_name": "subcategoryname22",
                    "sub_category_icon": ""
                }
            ]
        }
    ]
}

我尝试了一些方法。但是，我没能在字典中找到合适的元素。我的代码如下:

ATTEPMT 1:
var dict: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary

        for(var i = 0; i < (dict.valueForKey("data") as NSArray).count; i++)
        {
            self.categFromJson.addObject((dict.valueForKey("data") as NSArray) .objectAtIndex(i))

        }

        for(var i = 0; i < (categFromJson.valueForKey("category_child") as NSArray).count; i++)
        {
            self.sub_ct_FromArr.addObject((categFromJson.valueForKey("category_child") as NSArray) .objectAtIndex(i))

        }

        for(var i = 0; i < (sub_ct_FromArr.valueForKey("sub_category_name") as NSArray).count; i++)
        {
            self.sub_ct_name_arr.addObject((sub_ct_FromArr.valueForKey("sub_category_name") as NSArray) .objectAtIndex(i))

        }


//ATTEMPT 2
var dict: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary

for(var i = 0; i < (dict.valueForKey("data") as NSArray).count; i++)
{
    categFromJson.addObject((dict.valueForKey("data") as NSArray) .objectAtIndex(i))

    sub_ct_FromArr.addObject((categFromJson.valueForKey("category_child") as NSArray) .objectAtIndex(i))

    sub_ct_name_arr.addObject((sub_ct_FromArr.valueForKey("sub_category_name") as NSArray) .objectAtIndex(i))
}

但是，对于这两种尝试，最终输出都是错误的并且是相同的。 Bcos，编码如下。

//CODING
println(sub_ct_name_arr.objectAtIndex(0))

//Output for this Code
(subcategoryname1,subcategoryname2)
//REQUIRED Output
subcategoryname1

请多指教。我不知道那是什么问题。

Answer 1

首先，可视化您拥有的数据类型非常重要。

然后可以这样获取根对象，后面是哪个对象是哪个类型:

let dict = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSDictionary

let dataArray = dict["data"] as! [[String:AnyObject]]  // The array of dictionaries

for object in dataArray {
    let category_id = object["category_id"] as! Int
    let category_name = object["category_name"] as! String
    // etc
    let category_child = object["category_child"] as! [[String:AnyObject]]
    for child in category_child {
        let sub_category_id = child["sub_category_id"] as! Int
        let sub_category_name = child["sub_category_name"] as! String
        println(sub_category_id)
        println(sub_category_name)
    }
}

您也可以考虑使用类似 SwiftyJSON 的库如果您有很多解码工作要做。