Downloaded Json Contains Null value and app Crash ios swift [duplicate] - ios

Question

This question already has answers here:
What does "Fatal error: Unexpectedly found nil while unwrapping an Optional value" mean?
(16 answers)
Closed 5 years ago.
i am working an app in which data is downloaded from server in JSON format. but if Image value is nill then app crashed. i also set a default picture but cursor did not enter in else statement. Kindly guide me how i do my task correctly. Here is my code
func downloadUsersData(){
let email = UserDefaults.standard.value(forKey: "userEmail")
var urlString = "http://nexusvision.net/zeroone/selectuserbasic.php"
urlString.append("?")
urlString.append("id=\(email!)")
print("This is URL : \(urlString)")
let url = URL(string: urlString)
var request = URLRequest(url: url!)
request.httpMethod = "GET"
let task = URLSession.shared.dataTask(with: request) { data, response, error in
if error != nil{
print(error?.localizedDescription)
}
let data = data
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 { // check for http errors
print("statusCode should be 200, but is \(httpStatus.statusCode)")
print("response = \(response)")
}
let responseString = String(data: data!, encoding: .utf8)
print("all Countary responseString = \(responseString)")
let responseData = responseString
do {
let jsonValue = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as! NSDictionary
print("This is Json : \(jsonValue.value(forKey: "product"))")
if let profile = jsonValue.value(forKey: "product") as? NSArray
{
for profileData in profile{
if let dict = profileData as? NSDictionary{
if let firstName = dict.value(forKey: "firstname"){
print("Name is : \(firstName)")
self.defaults.set(firstName, forKey: "firstName")
}
if let lastName = dict.value(forKey: "lastname"){
print("Last Name : \(lastName)")
self.defaults.set(lastName, forKey: "lastName")
}
if let imageData = dict.value(forKey: "picture") {
print("This is Image Json: \(imageData)")
let convertToImage = imageData
let decodedData : NSData = NSData(base64Encoded: convertToImage as! String, options: NSData.Base64DecodingOptions.ignoreUnknownCharacters)!
let decodedimage: UIImage = UIImage(data: decodedData as Data)!
print("Thats Decoded : \(decodedimage)")
self.profilePicImageShow.image = decodedimage
}
else{
self.profilePicImageShow.image = UIImage(named: "Empty")
}
}
}
}
}
catch let error as NSError {
print(error)
}
}.resume()
}

Answer 1

Technically, key "picture" is not nil, its empty string according to the JSON response. So when you execute the code, it will go into the if statement and finally crash at
let decodedimage: UIImage = UIImage(data: decodedData as Data)! as decodedData is nil.
Answer:
Modify the your if statement as below
if let imageData = dict.value(forKey: "picture"), (imageData as! String) != "" {
This should fix your crash problem.

Answer 2

Replace
if let imageData = dict.value(forKey: "picture") {
print("This is Image Json: \(imageData)")
let convertToImage = imageData
let decodedData : NSData = NSData(base64Encoded: convertToImage as! String, options: NSData.Base64DecodingOptions.ignoreUnknownCharacters)!
let decodedimage: UIImage = UIImage(data: decodedData as Data)!
print("Thats Decoded : \(decodedimage)")
self.profilePicImageShow.image = decodedimage
} else {
self.profilePicImageShow.image = UIImage(named: "Empty")
}
with
let imageData = dict["picture"] as? NSData ?? UIImageJPEGRepresentation(UIImage(named: "Empty")!, 1.0)
self.profilePicImageShow.image = UIImage(data: imageData!)
Also, make sure that the key "picture" actually contains nil

Answer 3

You could add guard statements as follow:
guard let decodedData = NSData(base64Encoded: convertToImage as! String, options: NSData.Base64DecodingOptions.ignoreUnknownCharacters) else {
return
}
guard let decodedimage: UIImage = UIImage(data: decodedData as Data) else {
return
}
Since you are forcing an unwrap, if it fails to create an image from the data, your app will crash.
As a side note, you could use this and this, those are really great libs to work with HTTP Requests.

Answer 4

In my case I'll get URL from JSON and then download image with URL; So if url is nil then I'll add dummy image else I'll download Image from URL. Here is My Stuff :
var news = respone.result.value as! Dictionary<String,Any>
if let result:NSArray = news["stories"] as? NSArray
{
for i in 0..<result.count
{
let str = (((result[i] as! NSDictionary).value(forKey: "ximg") as! NSDictionary).value(forKey: "ipath") as? String)
if str == nil
{
self.news_url.append("nil")
}
else
{
self.news_url.append(str!)
}
}
}
self.tableview.reloadData()