How To Handle json null values in Swift? - json

Question

My application is crashing while pursing null json
I was tying to solve this issue since long time
you are the best who can assist me with this issue
func downloadJsonWithURLJB() {
let url=URL(string:"http://ccm-hotels.com/RixosJBR/IOS/api/Con4s.php")
do {
let allContactsData = try Data(contentsOf: url!)
let allContacts = try JSONSerialization.jsonObject(with: allContactsData, options: JSONSerialization.ReadingOptions.allowFragments) as! [String : AnyObject]
if let arrJSON = allContacts["Con+4"] as? [[String : Any]] {
for index in 0...arrJSON.count-1 {
let aObject = arrJSON[index] as! [String : AnyObject]
Con4Array.append(Con4s(DateCon4: (aObject["Date"] as? String)!, TimeCon4: (aObject["Time"] as? String)!,GuestNameCon4: (aObject["GuestName"] as? String)!, RoomCon4: (aObject["Room"] as? String)!, LimoCoCon4: (aObject["LimoCo"] as? String)!, DriverCon4: (aObject["Driver"] as? String)!, VehicleCon4: (aObject["Vehicle"] as? String)!, FlightCon4: (aObject["Flight"] as? String)!, PickUpCon4: (aObject["PickUp"] as? String)!, DropToCon4: (aObject["DropTo"] as? String)!, PaxCon4: (aObject["Pax"] as? String)!,TotalCon4: (aObject["Total"] as? String)!, CompleteCon4: (aObject["complete"] as? String)!))
}
}
DispatchQueue.main.async {
self.tableCon4.reloadData()
}
}
catch {}}

Answer 1

The exception
Can't form Range with upperBound < lowerBound
occurs due to the ugly objective-c-ish for loop. If the array is empty the upper bound is -1 which is less than the lower bound.
In Swift never use index based for loops if the index is actually not needed.
Replace
for index in 0...arrJSON.count-1 {
let aObject = arrJSON[index] as! [String : AnyObject]
with
for aObject in arrJSON {
If you do need the index use the enumerated() syntax
for (index, aObject) in arrJSON.enumerated() {
or the safe half-open range operator
for index in 0..<arrJSON.count {
Other bad practices:
Never load data from a remote URL with synchronous API Data(contentsOf not even on a background thread.
A JSON dictionary in Swift 3+ is [String:Any], never [String:AnyObject].
Variable and property names start with a lowercase letter.
.allowFragments is pointless if the expected type is a collection type.