alloc() error in swift - parsing

Question

So I've just updated my swift to 2.0 and obviously a couple of errors appeared in my code.
Thats what I have right now.
unc loadRssFeed(data: NSURL) {
var myRssParser : ParserManager = ParserManager.alloc().initWithURL(data) as! ParserManager
myRssFeed = myRssParser.feeds
tableView.reloadData()
}
Fixit suggests to change 'var' to 'let' and use object initializer instead of alloc(). But the problem is I've never used it before (granted my Swift experience is like four weeks).
Should I follow fixit instruction?
And how do I fix the alloc() problem.
Thanks!
Updated wit parser code:
class ParserManager: NSObject, NSXMLParserDelegate {
var parser = NSXMLParser()
var feeds = NSMutableArray()
var elements = NSMutableDictionary()
var element = NSString()
var ftitle = NSMutableString()
var link = NSMutableString()
var fdescription = NSMutableString()
var fdate = NSMutableString()
func initWithURL(url :NSURL) -> AnyObject {
startParse(url)
return self
}
func startParse(url :NSURL) {
feeds = []
parser = NSXMLParser(contentsOfURL: url)!
parser.delegate = self
parser.shouldProcessNamespaces = false
parser.shouldReportNamespacePrefixes = false
parser.shouldResolveExternalEntities = false
parser.parse()
}
func allFeeds() -> NSMutableArray {
return feeds
}
func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) {
self.element = elementName
if self.element == "item" {
self.ftitle = ""
self.fdescription = ""
self.fdate = ""
}
}
func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
if (elementName as NSString).isEqualToString("item") {
if ftitle != "" {
elements.setObject(ftitle, forKey: "title")
}
if fdescription != "" {
elements.setObject(fdescription, forKey: "description")
}
if fdate != "" {
elements.setObject(fdate, forKey: "pubDate")
}
feeds.addObject(elements)
}
}
func parser(parser: NSXMLParser, foundCharacters string: String?) {
if element.isEqualToString("title") {
ftitle.appendString(string!)
}else if element.isEqualToString("description") {
fdescription.appendString(string!)
}else if element.isEqualToString("pubDate") {
fdate.appendString(string!)
}
}
}

Answer 1

The fix should look like this:
let myRssParser = ParserManager(URL: data) as! ParserManager
Or maybe like this, depends upon how ParserManager has been written:
let myRssParser = ParserManager(url: data) as! ParserManager
There's even a possibility that you don't have to use the argument name:
let myRssParser = ParserManager(data) as! ParserManager

Answer 2

As discussed above, you should not call alloc and init... methods directly. Furthermore, the ParserManager class should not have a initWithURL method, but rather an init method with a URL parameter. The existing code is appearing to follow Objective-C patterns, but Swift has its own conventions.
But more broadly, I would advise against performing synchronous network requests, and when you're calling NSXMLParser(contentsOfURL:), that's what's happening. It's better to request data asynchronously, and then refactor the code to follow asynchronous patterns (e.g. completionHandler closures). For example:
class ParserManager: NSObject, NSXMLParserDelegate {
/// The NSMutableArray used internally by this class
private var feeds = NSMutableArray()
/// Initiate parsing asynchronously; note, I'm returning the `NSURLSessionTask` in case you want to cancel it at some later point
func parse(URL: NSURL, completionHandler: (NSMutableArray?, NSError?)->()) -> NSURLSessionTask {
let task = NSURLSession.sharedSession().dataTaskWithURL(URL) { data, response, error in
guard data != nil else {
dispatch_async(dispatch_get_main_queue()) {
completionHandler(nil, error)
}
return
}
let parser = NSXMLParser(data: data!)
parser.delegate = self
if parser.parse() {
dispatch_async(dispatch_get_main_queue()) {
completionHandler(self.feeds, nil)
}
} else {
dispatch_async(dispatch_get_main_queue()) {
completionHandler(nil, parser.parserError)
}
}
}
task.resume()
return task
}
// NSXMLParserDelegate methods implemented here
}
Then, you can use the completion handler syntax to specify what you want to do when the network request and parsing is done:
let URL = NSURL(string: "...")
let myRssParser = ParserManager()
myRssParser.parse(URL) { feeds, error in
guard feeds != nil else {
print(error)
return
}
// use `feeds` here, e.g.
self.feeds = feeds // update your local property
self.tableView.reloadData() // and reload the table
}
// but don't use `feeds` here, since it won't be done by the time we get here