How can I use swiftyJSON dictionaryValue as a usable string for a UILabel?

问题

I have a makeRequest() method inside a UITableViewController with the following code:

    func makeRequest() {

    Alamofire.request(.GET, self.foursquareEndpointURL, parameters: [
        //"VENUE_ID" : self.foursquareVenueID,
            "client_id" : self.foursquareClientID,
            "client_secret" : self.foursquareClientSecret,
            "v" : "20140806"
            ])
        .responseJSON(options: nil) { (_, _, data, error) -> Void in
        if error != nil {
            println(error?.localizedDescription)
        } else if let data: AnyObject = data {
            let jObj = JSON(data)
            if let venue = jObj["response"]["venue"].dictionaryValue as [String: JSON]? {
                self.responseitems = jObj
                println("venue is: \(venue)")
            }
            dispatch_async(dispatch_get_main_queue()) {
                self.tableView.reloadData() // Update UI
            }
        }
    }
}

also keep in mind that I have a property var responseitems:JSON = []

println("venue is: \(venue)") prints a nice looking response to console, so I know that is working correctly...

I also have a custom UITableViewCell class with a bindData() method with the following code:

func bindData() {
    println("VenueDetailHeaderCell data did set")
    self.venueDetailTitleLabel.text = self.headerInfo?["name"].stringValue
    let labelData = self.headerInfo?["name"].stringValue
    println("labelData is: \(labelData)")
}

As you can see, I am attempting to set a UILabel's text to the ["name"].stringValue in the JSON response. However, when I println("labelData is: \(labelData)") I get console output of labelData is: Optional("") which is obviously empty.

Here's a screenshot of what I'm trying to grab

What am I doing wrong here and how can I grab the name of the venue and assign my UILabel to it?

UPDATE:

I tried the following code

let labelData = self.headerInfo?["name"].error
    println("labelData is: \(labelData)")

And get a console output of: "Error Domain=SwiftyJSONErrorDomain Code=901 "Array[0] failure, It is not an array" UserInfo=0x7fd6d9f7dc10 {NSLocalizedDescription=Array[0] failure, It is not an array}" If that is of use to anyone. I am really confused here... Any ideas?

回答1:

The problem is that the headerInfo value is an error JSON object, because you're trying to access a dictionary with an integer index.

Note that var responseitems:JSON = [] does not create an array object. SwiftyJSON has auto-assignment-constructors (I'm new to swift, so not sure what the correct swift terminology is)... see this initialiser in the SwiftyJSON.swift source code:

extension JSON: ArrayLiteralConvertible {
    public init(arrayLiteral elements: AnyObject...) {
        self.init(elements)
    }
}

What this means is that when you do var responseitems:JSON = [] you are not creating an array, you are creating a JSON object that is constructed with an empty array using the above init method. Then when you do self.responseitems = jObj you are re-assigning that responseitems variable to a JSON object with a dictionary in it. Therefore self.responseitems[0] is invalid.

Also note that with SwiftyJSON, there is no such thing as an optional JSON object. I notice in your comment you say that you do var headerInfo:JSON? ... - it's not possible to have an optional JSON.

var headerInfo: JSON = nil

The above is possible - this uses another auto-initialiser that initialises a valid JSON object that represents the JSON null value.

So, how to fix it?

When you assign headerInfo do it like this:

let headerInfo = self.responseitems["response"]["venue"]

And now in bindData you can do:

self.venueDetailTitleLabel.text = self.headerInfo["name"].stringValue

Note that all of the above assumes Swift 1.2 and SwiftyJSON >= 2.2 - also after you've understood the above and corrected the issue, you will probably want to refactor the code a bit to reflect the corrected understanding of the data-model.

回答2:

The way to parse is the next

element: JSONValue //Something with JSONValue
if let title = element["name"]?.string {
    cell.title.text = title
}

来源：https://stackoverflow.com/questions/29725241/how-can-i-use-swiftyjson-dictionaryvalue-as-a-usable-string-for-a-uilabel