How to loop through JSON with SwiftyJSON?

问题

I have a json that I could parse with SwiftyJSON :

if let title = json["items"][2]["title"].string {
     println("title : \(title)")
}

Works perfectly.

But I couldn't loop through it. I tried two methods, the first one is

// TUTO :
//If json is .Dictionary
for (key: String, subJson: JSON) in json {
    ...
}
// WHAT I DID :
for (key: "title", subJson: json["items"]) in json {
    ...
}

XCode didn't accept the for loop declaration.

The second method :

// TUTO :
if let appArray = json["feed"]["entry"].arrayValue {
     ...
}
// WHAT I DID :
if let tab = json["items"].arrayValue {
     ...
}

XCode didn't accept the if statement.

What am I doing wrong ?

回答1:

If you want loop through json["items"] array, try:

for (key, subJson) in json["items"] {
    if let title = subJson["title"].string {
        println(title)
    }
}

As for the second method, .arrayValue returns non Optional array, you should use .array instead:

if let items = json["items"].array {
    for item in items {
        if let title = item["title"].string {
            println(title)
        }
    }
}

回答2:

I Find it a bit strange explained myself, because actually using:

for (key: String, subJson: JSON) in json {
   //Do something you want
}

gives syntax errors (in Swift 2.0 atleast)

correct was:

for (key, subJson) in json {
//Do something you want
}

Where indeed key is a string and subJson is a JSON object.

However I like to do it a little bit different, here is an example:

//jsonResult from API request,JSON result from Alamofire
   if let jsonArray = jsonResult?.array
    {
        //it is an array, each array contains a dictionary
        for item in jsonArray
        {
            if let jsonDict = item.dictionary //jsonDict : [String : JSON]?
            {
                //loop through all objects in this jsonDictionary
                let postId = jsonDict!["postId"]!.intValue
                let text = jsonDict!["text"]!.stringValue
                //...etc. ...create post object..etc.
                if(post != nil)
                {
                    posts.append(post!)
                }
            }
        }
   }

回答3:

In the for loop, the type of key can't be of the type "title". Since "title" is a string, go for : key:String. And then Inside the Loop you can specifically use "title" when you need it. And also the type ofsubJson has to be JSON.

And Since a JSON file can be considered as a 2D array, the json["items'].arrayValue will return multiple objects. It is highly advisable to use : if let title = json["items"][2].arrayValue.

Have a look at : https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Types.html

回答4:

Please check the README

//If json is .Dictionary
for (key: String, subJson: JSON) in json {
   //Do something you want
}

//If json is .Array
//The `index` is 0..<json.count's string value
for (index: String, subJson: JSON) in json {
    //Do something you want
}

回答5:

you can iterate through the json by:

for (_,subJson):(String, JSON) in json {

   var title = subJson["items"]["2"]["title"].stringValue

   print(title)

}

have a look at the documentation of SwiftyJSON. https://github.com/SwiftyJSON/SwiftyJSON go through the Loop section of the documentation

来源：https://stackoverflow.com/questions/28365939/how-to-loop-through-json-with-swiftyjson

标签

ios

json

swift

swifty-json