0. Original Code.swift

for appID in appIDs {
    let urlString = "https://itunes.apple.com/lookup?id=" + appID
    if let
        url = NSURL(string:urlString),
        data = NSData(contentsOfURL: url),
        json = NSJSONSerialization.JSONObjectWithData(
            data, options: NSJSONReadingOptions(0),
            error: nil) as? NSDictionary,
        resultsList = json["results"] as? NSArray,
        results = resultsList.firstObject as? NSDictionary,
        name  : AnyObject = results["trackName"],
        price : AnyObject = results["formattedPrice"] {
            println("\(name): \(price)")
    }
}

1. Starting point.swift

func ShowPrices(productURLStrings: [String]) {
    println("Today's prices")
    for productURLString in productURLStrings {
        var urlString = FetchQuery(productURLString)
        if let json = JSON.fetchURLString(urlString),
            dict = json.rawValue as? NSDictionary,
            resultsList = dict["results"] as? NSArray,
            results = resultsList.firstObject as? NSDictionary,
            name = results["trackName"] as? NSString,
            formattedPrice = results["formattedPrice"] as? NSString {
                println("\(name): \(formattedPrice)")
        }
    }
    println()
}

func CheckRatings(productURLStrings: [String]) {
    println("Checking ratings")
    for productURLString in productURLStrings {
        var urlString = FetchQuery(productURLString)
        if let json = JSON.fetchURLString(urlString),
            dict = json.rawValue as? NSDictionary,
            resultsList = dict["results"] as? NSArray,
            results = resultsList.firstObject as? NSDictionary,
            name = results["trackName"] as? NSString {
                print("\(name): ")
                if let averageUserRating = results["averageUserRating"] as? NSNumber {
                    println("\(averageUserRating) stars") // iBooks
                } else if let trackContentRating = results["trackContentRating"] as? NSNumber {
                    println("\(trackContentRating) stars") // iOS, OS X
                } else {
                    println("ratings not available")
                }
        }
    }
    println()
}

2. With copious comments.swift

func ShowPrices(productURLStrings: [String]) {
    println("Today's prices")
    for productURLString in productURLStrings {
        var urlString = FetchQuery(productURLString) // format URL
        if let json = JSON.fetchURLString(urlString), // fetch JSON
            dict = json.rawValue as? NSDictionary, // fetch dict
            resultsList = dict["results"] as? NSArray, // fetch results array
            results = resultsList.firstObject as? NSDictionary, // fetch info
            name = results["trackName"] as? NSString, // fetch track name
            formattedPrice = results["formattedPrice"] as? NSString { // fetch price
                println("\(name): \(formattedPrice)")
        }
    }
    println()
}

func CheckRatings(productURLStrings: [String]) {
    println("Checking ratings")
    for productURLString in productURLStrings {
        var urlString = FetchQuery(productURLString) // format URL
        if let json = JSON.fetchURLString(urlString), // fetch JSON
            dict = json.rawValue as? NSDictionary, // fetch dict
            resultsList = dict["results"] as? NSArray, // fetch results array
            results = resultsList.firstObject as? NSDictionary, // fetch info
            name = results["trackName"] as? NSString { // fetch track name
                print("\(name): ")

                // Rating keys vary by content type
                if let averageUserRating = results["averageUserRating"] as? NSNumber {
                    println("\(averageUserRating) stars") // iBooks
                } else if let trackContentRating = results["trackContentRating"] as? NSNumber {
                    println("\(trackContentRating) stars") // iOS, OS X
                } else {
                    println("ratings not available")
                }
        }
    }
    println()
}

3. After Allmanizing.swift

func ShowPrices(productURLStrings: [String])
{
    println("Today's prices")
    for productURLString in productURLStrings
    {
        var urlString = FetchQuery(productURLString) // format URL
        
        if let json = JSON.fetchURLString(urlString), // fetch JSON
            dict = json.rawValue as? NSDictionary, // fetch dict
            resultsList = dict["results"] as? NSArray, // fetch results array
            results = resultsList.firstObject as? NSDictionary, // fetch info
            name = results["trackName"] as? NSString, // fetch track name
            formattedPrice = results["formattedPrice"] as? NSString // fetch price
        {
                println("\(name): \(formattedPrice)")
        }
    }
    println()
}

func CheckRatings(productURLStrings: [String])
{
    println("Checking ratings")
    for productURLString in productURLStrings
    {
        var urlString = FetchQuery(productURLString) // format URL
        
        if let json = JSON.fetchURLString(urlString), // fetch JSON
            dict = json.rawValue as? NSDictionary, // fetch dict
            resultsList = dict["results"] as? NSArray, // fetch results array
            results = resultsList.firstObject as? NSDictionary, // fetch info
            name = results["trackName"] as? NSString // fetch track name
        {
                print("\(name): ")
            
                // Rating keys vary by content type
                if let averageUserRating = results["averageUserRating"] as? NSNumber
                {
                    println("\(averageUserRating) stars") // iBooks
                }
                else if let trackContentRating = results["trackContentRating"] as? NSNumber
                {
                    println("\(trackContentRating) stars") // iOS, OS X
                }
                else
                {
                    println("ratings not available")
                }
        }
    }
    println()
}

4.Other customization.swift

func ShowPrices(productURLStrings: [String])
{
    println("Today's prices")
    for productURLString in productURLStrings {
        var urlString = FetchQuery(productURLString)
        if let json = JSON.fetchURLString(urlString) {
            
            // Name
            if let name = json.valueForKeypath(
                ["results", 0, "trackName"]) as? String {
                    print("\(name): ") }
            
            // Formatted Price
            if let formattedPrice = json.valueForKeypath(
                ["results", 0, "formattedPrice"]) as? String {
                    println("\(formattedPrice)") }

        }
    }
    println()
}

func CheckRatings(productURLStrings: [String])
{
    println("Checking ratings")
    for productURLString in productURLStrings {
        var urlString = FetchQuery(productURLString)
        if let json = JSON.fetchURLString(urlString) {
            
            // Name
            if let name = json.valueForKeypath(
                ["results", 0, "trackName"]) as? String {
                print("\(name): ") }
            
            // Rating keys vary by content type
            if let averageUserRating = json.valueForKeypath(
                ["results", 0, "averageUserRating"]) as? NSNumber {
                println("\(averageUserRating) stars") // iBooks
            }
            else if let trackContentRating = json.valueForKeypath(
                ["results", 0, "trackContentRating"]) as? NSNumber {
                println("\(trackContentRating) stars") // iOS, OS X
            }
            else {
                println("ratings not available")
            }
        }
    }
    println()
}

5.JSON enum for#4.swift

extension Array {
    func atIndex(index: UInt) -> Element? {
        return Int(index) < count ? self[Int(index)] : nil
    }
}

public enum JSON : Printable {
    case NullValue
    case NumberValue(Double)
    case StringValue(String)
    case ArrayValue([NSObject])
    case DictionaryValue([NSObject:AnyObject])
    
    public var rawValue: AnyObject? {
        switch self {
        case .NullValue: return nil
        case .NumberValue (let d): return d
        case .StringValue (let s): return s
        case .ArrayValue (let a): return a
        case .DictionaryValue (let d): return d
        }
    }
    
    public var description : String {
        switch self {
        case .NullValue: return "Null"
        case .NumberValue (let d): return "Number<\(d)>"
        case .StringValue (let s): return "String<\(s)>"
        case .ArrayValue (let a): return "Array<\(a)>"
        case .DictionaryValue (let d): return "Dict<\(d)>"
        }
    }
    
    // Fallback initializer is null
    public init() {self = .NullValue}
    
    // Initialize with type
    public init?<T>(_ t : T){
        switch t {
        case let value as NSNull: self = .NullValue
        case let value as Double: self = .NumberValue(value)
        case let value as String: self = .StringValue(value)
        case let value as [NSObject]: self = .ArrayValue(value)
        case let value as [NSObject:AnyObject]: self = .DictionaryValue(value)
        default: return nil
        }
    }
    
    // Initializer entry point for optionals
    public init?<T>(_ t : T?){
        if let t = t {self.init(t)} else {self.init()}
    }
    
    public static func fetchURLString(urlString : String) -> JSON? {
        if let
            url = NSURL(string:urlString),
            data = NSData(contentsOfURL: url),
            jsonRep : AnyObject = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions(0), error: nil) {
                return JSON(jsonRep)
        }
        return nil
    }

    public func valueForKey(index : UInt) -> JSON? {
        switch self {
        case .ArrayValue(let array): return JSON(array.atIndex(index))
        default: return nil
        }
    }
    
    public func valueForKey(string: String) -> JSON? {
        switch self {
        case .DictionaryValue(let dict): return JSON(dict[string])
        default: return nil
        }
    }
    
    public func jsonForKeypath(keypath: ArraySlice<AnyObject>) -> JSON? {
        if isEmpty(keypath) {return self}
        switch keypath.first {
        case let stringValue as String: return valueForKey(stringValue)?.jsonForKeypath(dropFirst(keypath))
        case let uintValue as UInt: return valueForKey(uintValue)?.jsonForKeypath(dropFirst(keypath))
        default: return nil
        }
    }
    
    public func valueForKeypath(keypath : ArraySlice<AnyObject>) -> AnyObject? {
        return jsonForKeypath(keypath)?.rawValue
    }
}

How about a helper function?

func firstResult(productURLString: String) -> NSDictionary?
{
    if let json = JSON.fetchURLString(FetchQuery(productURLString)),
        dict = json.rawValue as? NSDictionary,
        resultsList = dict["results"] as? NSArray,
        result = resultsList.firstObject as? NSDictionary
    {
        return results
    }
    return nil
}

func ShowPrices(productURLStrings: [String])
{
    println("Today's prices")
    for productURLString in productURLStrings
    {
        if let result = firstResult(productURLString),
            name = result["trackName"] as? NSString,
            formattedPrice = result["formattedPrice"] as? NSString
        {
                println("\(name): \(formattedPrice)")
        }
    }
    println()
}

func CheckRatings(productURLStrings: [String])
{
    println("Checking ratings")
    for productURLString in productURLStrings
    {
        if let result = firstResult(productURLString),
            name = result["trackName"] as? NSString
        {
            print("\(name): ")

            // Rating keys vary by content type
            if let rating = results["averageUserRating"] as? NSNumber ?? result["trackContentRating"] as? NSNumber
            {
                println("\(rating) stars")
            }
            else
            {
                println("ratings not available")
            }
        }
    }
    println()
}

Great code challenge!

After some investment into helper functions and operators, we can do things like this:

// MARK: Main functions
func ShowPrices(productURLStrings: [String]) {
    println("Today's prices")

    productURLStrings 
        ➜ FetchQueryURL  
        ➜ NSURL.fetchJSON      
        ➜ usingFirst(JSON.extractPrice) 
        ➜ { "\($0.name): \($0.formattedPrice)" }
        ➜ println

    println()
}

func CheckRatings(productURLStrings: [String]) {
    println("Checking ratings")

    productURLStrings
        ➜ FetchQueryURL 
        ➜ NSURL.fetchJSON 
        ➜ usingFirst(JSON.extractRating)    
        ➜ { "\($0.name): \($0.starDescription)" } 
        ➜ println

    println()
}

See this gist.

Here's an example of how I'd approach the problem. Full gist can be found here

let json = JSONFromFile("example")

let product = json
  >>- toJSONArray("results")
  >>- first
  >>- productFromJSON

product?.name                 // Yelp
product?.formattedPrice       // Free
product?.averageUserRating    // 4
product?.trackContentRating   // 12+