Error parsing JSON in Swift2 - json

Question

Hello I am having an error when parsing some JSON in Swift, my error is:
'Invalid conversion from throwing function of type '(_, _, _) throws -> Void' to non-throwing function type '(NSData?, NSURLResponse?, NSError?) -> Void'
I think this is something to do with catching an error somewhere but I cannot figure out where this would go could anyone help me please? Here is my source code:
import UIKit
import CoreData
class MasterViewController: UITableViewController {
var detailViewController: DetailViewController? = nil
override func viewDidLoad() {
super.viewDidLoad()
var appDel: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
var context: NSManagedObjectContext = appDel.managedObjectContext
let url = NSURL(string: "https://www.googleapis.com/blogger/v3/blogs/10861780/posts?key=AIzaSyBwmI4AzMnBmr7oSVeL0EHdzMjXV1aATnQ")
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithURL(url!, completionHandler: { (data, response, error) -> Void in
if error != nil {
print(error)
} else {
//print(NSString(data: data!, encoding: NSUTF8StringEncoding))
do {
let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions(rawValue: 0)) as! NSDictionary
if jsonResult.count > 0 {
if let items = jsonResult["items"] as? NSArray {
for items in items {
print(items)
if let title = items["title"] as? String {
if let content = items["content"] as? String {
var newPost: NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName("Posts", inManagedObjectContext: context)
newPost.setValue(title, forKey: "title")
newPost.setValue(content, forKey: "content")
do {
try context.save()
}
}
}
}
}
}
} catch let error as NSError {
print(error)
}
var request = NSFetchRequest(entityName: "Posts")
request.returnsObjectsAsFaults = false
var results = try context.executeFetchRequest(request)
self.tableView.reloadData()
}
})
task.resume()
}
Thanks!

Answer 1

It looks like you haven't taken care of all the throwing functions using do-try-catch method.
According to the Swift 3 Documentation at https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/ErrorHandling.html
In your case, you seem to have forgotten to take care of the error thrown at var- results. Also, you haven't handled the throwing function session.dataTaskWithURL with a do-try-catch method.
You should not be getting this error if you modify your code as following:
override func viewDidLoad() {
super.viewDidLoad()
var appDel: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
var context: NSManagedObjectContext = appDel.managedObjectContext
let url = NSURL(string: "https://www.googleapis.com/blogger/v3/blogs/10861780/posts?key=AIzaSyBwmI4AzMnBmr7oSVeL0EHdzMjXV1aATnQ")
let session = NSURLSession.sharedSession()
do {
let task = try session.dataTaskWithURL(url!, completionHandler: { (data, response, error) -> Void in
if error != nil {
print(error)
} else {
//print(NSString(data: data!, encoding: NSUTF8StringEncoding))
do {
let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions(rawValue: 0)) as! NSDictionary
if jsonResult.count > 0 {
if let items = jsonResult["items"] as? NSArray {
for items in items {
print(items)
if let title = items["title"] as? String {
if let content = items["content"] as? String {
var newPost: NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName("Posts", inManagedObjectContext: context)
newPost.setValue(title, forKey: "title")
newPost.setValue(content, forKey: "content")
do {
try context.save()
} catch let error1 as NSError { // this is for context.save
print(error1)
}
}
}
}
}
}
}
var request = NSFetchRequest(entityName: "Posts")
request.returnsObjectsAsFaults = false
do{
var results = try context.executeFetchRequest(request)
} catch let error2 as NSError { // this is for context.executeFetchRequest
print(error2)
}
self.tableView.reloadData()
}
})
task.resume()
} catch let error3 as NSError { // this is for session.dataTaskWithURL
print(error3)
}
}
Hope this helps ! Cheers !