Issue raised, while retriving datas from JSON by using swift

问题

I am retrieving datas from JSON by using swift. I am new to JSON. I don't how to retrieve this nested values. My JSON format is below.

//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": ""
                }
            ]
        }
    ]
}

I have tried some ways. But, I failed to get proper elements in dictionary. My code is below:

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))
}

But, for both attempt, final output is wrong and same. Bcos, coding below.

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

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

Kindly guide me. I don't know what is that issue.

回答1:

First, it's important to visualize what kind of data you have.

Then you can get root objects like this, following which object is of which type:

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)
    }
}

You also might consider using a library like SwiftyJSON if you have a lot of decoding to do.

来源：https://stackoverflow.com/questions/29649862/issue-raised-while-retriving-datas-from-json-by-using-swift

标签

ios

swift

nsdictionary