Pull to refresh returns empty array in Swift 3 iOS 10 - ios10

Question

I have recently migrated my iOS app to support iOS 10 with Swift 2.3 and have encountered an issue which was previously working fine on iOS 9 / Swift.
Problem goes like this:
I have a UITableView which loads up sections and rows, at the first instance everything loads fine. But when I do a pull to refresh i am clearing out the array by totalSectionData.removeAllObjects(). now when the refresh is executed it is throwing an error [__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array. It is obvious I am calling the function to reload the data from server after clearing out the array.
On further investigating and putting breakpoints I found that it is not going inside numberOfSectionsInTableView and numberOfRowsInSection while I do refresh; On the first time it does goes inside it. tableView and delegate are connected properly.
If i comment totalSectionData.removeAllObjects() then it works fine but I get duplicate rows.
It was working fine on previous iOS 9 / Swift 2, I tested the code again on previous version to double confirm.
Is there anything that's new in iOS 10 / Swift 2.3 that I am missing / doing wrong way.
Refresh code:
func refresh(sender:AnyObject)
{
// Code to refresh table view
tableView.allowsSelection = false
totalSectionData.removeAllObjects()
get_data_from_url(json_data_url)
}
After the JSON data is received I am calling reloadData
func do_table_refresh()
{
dispatch_async(dispatch_get_main_queue(), {
self.tableView.reloadData()
self.refreshControl.endRefreshing()
self.hideActivityIndicator()
self.tableView.allowsSelection = true
return
})
}
// Fetch JSON
func get_data_from_url(url:String)
{
let url:NSURL = NSURL(string: url)!
let session = NSURLSession.sharedSession()
let request = NSMutableURLRequest(URL: url)
request.HTTPMethod = "GET"
request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringCacheData
tableView.allowsSelection = false
let task = session.dataTaskWithRequest(request) {
(
data, response, error) in
guard let _:NSData = data, let _:NSURLResponse = response where error == nil else {
print("error")
return
}
self.showActivityIndicator()
dispatch_async(dispatch_get_main_queue(), {
let json = NSString(data: data!, encoding: NSASCIIStringEncoding)
self.extract_json(json!)
// self.activityIndicator.stopAnimating()
return
})
}
task.resume()
}
func extract_json(data:NSString)
{
var parseError: NSError?
let jsonData:NSData = data.dataUsingEncoding(NSASCIIStringEncoding)!
let json: AnyObject?
do {
json = try NSJSONSerialization.JSONObjectWithData(jsonData, options: [])
} catch let error as NSError {
parseError = error
json = nil
}
if (parseError == nil)
{
if let list:NSArray = json as? NSArray
{
print ("Inside if let")
let lblArray:NSArray = (list.valueForKey("level_number") as?NSArray)!
let data = NSOrderedSet(array: lblArray as [AnyObject])
for value in data {
let resultPredicate : NSPredicate = NSPredicate(format: "level_number == %d", value.integerValue)
let arrayData:NSArray = list.filteredArrayUsingPredicate(resultPredicate)
let lblArray:NSArray = (arrayData.valueForKey("part_number") as?NSArray)!
let dataValue = NSOrderedSet(array: lblArray as [AnyObject])
for index in dataValue {
let resultPredicate : NSPredicate = NSPredicate(format: "part_number == %d", index.integerValue)
totalSectionData.addObject(arrayData.filteredArrayUsingPredicate(resultPredicate))
}
}
for i in 0 ..< list.count
{
if let data_block = list[i] as? NSDictionary
{
TableData.append(datastruct(add: data_block))
}
}
do
{
try read()
}
catch
{
}
do_table_refresh()
}
}
}