So I have created a function which I use for all my requests, which will retry the request if fails and also add some of my headers to all requests for security.
The problem I am having is if data is nil, no values are being set in data.
Where am I going wrong here?
func performAndRetryRequestWithURL(method: Alamofire.Method, url: String, parameters: [String: AnyObject]?, completionHandler:(AnyObject?) -> Void) {
var data: [String: AnyObject]?
if (parameters != nil) {
data = parameters!
} else {
data = [String: AnyObject]?()
}
var unixTime = NSDate().timeIntervalSince1970
// I tried both ways to add timestamp
data?["timestamp"] = unixTime
data?.updateValue(unixTime, forKey: "timestamp")
data?.updateValue(hash("myfakekey"), forKey: "key")
println(data)
If parameters has data it seems to append, but if parameters is nil, data will be nil also.
Make data not optional:
var data = parameters ?? [String: AnyObject]()
If parameters is not nil, data will be assigned to parameter's unwrapped value. Otherwise, it will be initialized to an empty, non-optional dictionary.
The problem is in this line:
data = [String: AnyObject]?()
This looks at first glance like it should create an empty dictionary of type [String: AnyObject], but what it actually does is create an Optional dictionary that is initialized to nil. Get rid of the ? and it should work:
data = [String: AnyObject]()
Or, alternatively, since you've already identified data as being a dictionary of type [String: AnyObject]?, you could simply write:
data = [:]
That would create an empty dictionary as well.
Related
I'm a beginner in swift and I'm currently making an app that makes a web request. I've been trying to parse this JSON Data but the nested data is just really hard to wrap my head around:
"abilities": [
{
"ability": {
"name": "chlorophyll",
"url": "https://pokeapi.co/api/v2/ability/34/"
},
"is_hidden": true,
"slot": 3
},
{
"ability": {
"name": "overgrow",
"url": "https://pokeapi.co/api/v2/ability/65/"
},
"is_hidden": false,
"slot": 1
}
]
JSon Serialization Code
let jsonAny = try JSONSerialization.jsonObject(with: data, options: [])
guard let json = jsonAny as? [String: Any] else { return }
This is my attempt to manually parse the JSON Data
private func parsePokemonManual(json: [String: Any]) -> Pokemon {
let abilities = json["abilities"] as? [String: Any] ?? [String: Any]()
return Pokemon(abilities: abilities)
}
}
These are the structs that I made to hold the data.
struct Abilities {
let ability : Ability
struct Ability {
let name : String
}
}
How do I successfully parse the JSON Data into an object of Pokemon structure?
With this code so fat I am getting the error "Cannot convert the value of type '[String : Any]' to expected argument type '[Abilities]'. My problem is that I don't know what type to cast the abilities as and that my struct 'Abilities' is also incorrect.
There are 3 problems with your attempt although one might argue there is only 1, that you should use Codable instead but lets stay with JSONSerialization here. The problems are
You are reading the json wrong and should cast not to a dictionary but an array of dictionaries when accessing "abilities"
Your struct is to complicated, maybe because of the previous problem
Lastly, you can't cast into a custom type, you need to convert or map the data into your type by telling exactly what values to use and how because the compiler doesn't understand how to do it.
First the struct can be simplified to
struct Ability {
let name : String
}
And the rest is fixed in the function parsePokemonManual. First get "abilities" and cast to an array of dictionaries. Then map each item in the array by getting "ability" and casting it to a dictionary that is used to get the "name" value that is then used when creating an instance of Ability
private func parsePokemonManual(json: [String: Any]) -> [Ability] {
guard let abilities = json["abilities"] as? [[String: Any]] else {
return []
}
return abilities.compactMap { dict in
guard let ability = dict["ability"] as? [String: String], let name = ability["name"] else { return nil }
return Ability(name: name)
}
}
I got notification in didreceiveRemoteNotification but I can not cast userInfo to dictionary of type [String: Any]
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
let dict = userInfo as! [String: Any]
if let response = dict["message"] as? [String: Any], let baseResponse = Mapper<NotificationModel>().map(JSON: response) {
//do some stuff
}
}
when I try to cast dict["message"] as! [String: Any] error happens and it says:
Could not cast value of type '__NSCFString' (0x1cfa84f90) to 'NSDictionary' (0x1cfa85bc0).
Here is dict["message"] when I print it in console:
▿ Optional<Any>
- some : {"sender":
{"avatar_url":"http:\/\/api.moneyar.com\/APIs\/images\/15783070400.jpg","user_id":"15783","name":"mahdi moqadasi"}
,"conversation_id":"15783"
,"message_id":103597,
"time":1546778745,
"type":1,"message":"foo"
}
For the following answer, the code is not tested against a compiler, there might be some typo issue that could be easily fixed, some of them are intentionally done to exergue the logic behind it, and not add with if let/guard let, as?, etc. that are needed but add noise in the explanation.
I won't repeat #vadian answer, which is correct an explain why it fails.
So we are clear that dict["message"] is a String.
A piece of information that you seem to be missing in the JSON acronym is for what stands the "N": Notation.
When you printed dict["message"], you didn't have really a key/value object, you have a String representing a key-value object, but not in a Swift representation. You printed JSON Stringified (because it's clearly more readable that hex data JSON). If after the answer you print jsonDict, you'll see that the output structure might be different.
So, as always, your basic tools are:
Data <== data(encoding:)/init(data:encoding:) ==> String
Data <== jsonObject(with:options:)/data(withJSONObject:options:) ==> Array or Dictionary //I bypass voluntarily the specific case of String at top level
Let's do it then!
let jsonStringifiedString = dict["message"] as String
let jsonStringifiedData = jsonStringifiedString.data(using: .utf8) as Data
let jsonDict = try JSONSerialization.jsonObject(with: jsonStringifiedData, options: []) as [String: Any]
let baseResponse = Mapper<NotificationModel>().map(JSON: jsonDict)
If I were you, I'd look into Mapper if there is no way to do something like:
let baseResponse = Mapper<NotificationModel>().map(JSONData: jsonStringifiedData)
or
let baseResponse = Mapper<NotificationModel>().map(JSONString: jsonStringifiedString)
Because there are sometimes JSONStringified embedded in JSON, where you might need to call it on a String or on a Data directly.
Or just because the basic URLSession request returns a Data object in its closure, and you want to use it directly.
The error
Could not cast value of type '__NSCFString' (0x1cfa84f90) to 'NSDictionary' (0x1cfa85bc0).
is clear. The value of key message is a string
of type is the real type
to is the expected wrong type
if let response = dict["message"] as? String, ...
This question already has answers here:
Printing optional variable
(15 answers)
Cannot get rid of Optional() string
(5 answers)
Closed 5 years ago.
this is my code:
func uplouadPost() {
// shortcut to data to be php
let parseJSON = UserDefaults.standard.value(forKey: "parseJSON") as?
NSDictionary
let userID = parseJSON!["userID"] as! String
....
if error == nil {
do {
// json containes $returnArray from php
let json = try JSONSerialization.jsonObject(with: data!,
options: .mutableContainers) as? NSDictionary
print("========================\(userID)")
print I get ========================Optional(23)
But I don't want Optioanl
how to just get 23
What's more, I tried to unwrap the "userID" by this way. However it doesn't work
let unwrappedUserID = [userID]
print (unwrappedUserID)
Thank you guys
The best method of checking for and unwrapping Optionals is using either a guard statement or if-let statements.
So suppose you have a dictionary defined as:
let parseJson: [String: Any]? = ["userId": 23]
Even though it has a value, it is still an Optional type so to access the values in the dictionary we want, we need to check for the possibility of it having a nil value, assuming we didn't create it and know that it has a real value.
Using if-let statements, we can do:
if let json = parseJson {
// WILL ONLY EXECUTE IF parseJson IS NOT nil
// json is now of type [String: Any] instead of [String: Any]?
let userId = json["userId"]
print("=========\(userId)") // =========23
}
This creates a new scope where the json constant now contains the non-nil and unwrapped optional value of parseJson. In that case if parseJson did equal nil, then the code inside of the if-let block would not execute.
The other option is a guard statement, which is very similar.
guard let json = parseJson else {
// ONLY EXECUTES IF parseJson IS nil
// MUST EXIT CURRENT SCOPE AS A RESULT
return // or throw NSError()
}
let userId = json["userId"]
print("==========\(userId)") // ==========23
In this case, the code after the guard will only execute if parseJson is non-nil because the inside of the guard block must exit the scope.
Try this, let unwrappedUserID = userID!
I am creating simple Json Parser that works like that: I have JsonData class that contains Anyobject as data. When I use jsonData["key"] it returns JsonData to i can chain jsonData["key"]["key2"] etc.
My question is how can I implement that class so i could cast it to lets say String:
jsonData["key"] as String without using some workarouds like
jsonData["key"].data as String
Code:
class JsonData:CustomStringConvertible{
let data:AnyObject
var description: String{
get{
return "\(data)"
}
}
init(_ data: Data) {
self.data = try! JSONSerialization.jsonObject(with: data, options: []) as! [[String:AnyObject]]
}
init(_ data: AnyObject) {
self.data = data
}
subscript(key:String) -> JsonData{
let newData = data as! [String:AnyObject]
let test = newData[key]!
return JsonData(test)
}
subscript(index:Int) ->JsonData{
let newData = data[index]!
return JsonData(newData)
}
}
In order to do this, you'd add another overload, but it won't work like you're thinking.
subscript(key: String) -> String {
let newData = data as! [String:AnyObject]
return newData[key] as! String
}
So then jsonData["key"] as String works, but jsonData["key"]["key2"] is ambiguous and you'd have to write it (jsonData["key"] as JsonData)["key2"] which probably isn't what you want.
The short answer to this is don't do this. If you need this much access to JSON, you're probably storing your data incorrectly. Parse it to structs as quickly as you can, and then work with structs. Convert the structs back to JSON when you want that. Extensive work with AnyObject is going to break your brain and the compiler over and over again. AnyObject is a necessary evil, not an every day tool. Soon you will encounter that terrible day that you have an AnyObject? and the compiler just breaks down in tears. Well, at least it isn't Any.
Putting that aside, the better solution is to use labeled-subscripts.
subscript(string key: String) -> String {
let newData = data as! [String:AnyObject]
return newData[key] as! String
}
Now you can access that as json[string: "key"] rather than json["key"] as String.
I have a function in Swift that needs to be able to handle multiple types. Specifically, it needs to be able to parse both Dicts and Strings.
The problem I have is the Dicts could be several types, depending on their origin. So I could be provided with [String:Any] or [String:String] (coming from Swift) or [String:AnyObject] (coming from objc). The top level parsing function takes Any, which it then tests for specific types and attempts to parse them.
At first I just tried testing for if let dict = object as? [String:Any], but if I passed in another type [String:AnyObject] or [String:String] it failed. So I tried testing each type:
func parseLink(object: Any) {
if let dict = object as? [String:Any] {
return self.parseDict(dict)
} else if let dict = object as? [String:AnyObject] {
return self.parseDict(dict)
} else if let dict = object as? [String:String] {
return self.parseDict(dict)
} else if let string = object as? String {
return parseURL(string)
}
}
func parseDict(dict: [String:Any]) { ..... }
So I've created some Unit Tests to test the behavior:
func testDictTypes() {
let testDict: [String:Any] = [ "orgId" : "123456789" ]
let link = OrgContextLinkParser().parseLink(testDict)
XCTAssertNotNil(link)
let testDict1: [String:AnyObject] = [ "orgId" : "123456789" ]
let link2 = OrgContextLinkParser().parseLink(testDict1)
XCTAssertNotNil(link2)
let testDict3: [String:String] = [ "orgId" : "123456789" ]
let link3 = OrgContextLinkParser().parseLink(testDict3)
XCTAssertNotNil(link3)
}
This all compiles fine, but I get a fatal runtime error if a [String:AnyObject] is passed in. This is troubling since Swift's type system is supposed to prevent these kind of errors and I get no warning or errors thrown when I compile.
I also really don't want to duplicate the exact same logic multiple times just to handle different dict types. I.E., handling [String:Any], [String:AnyObject] and [String:String] have virtually the exact same logic.
The only possible solution I've seen is to actually duplicate the dictionary, which seems rather expensive (Convert [String: AnyObject] to [String: Any]). For performance reasons, it seems better to just copy paste the code and change the function signatures... but really!? That's seems excessive.
The best solution seems to be to parse a Dict as [String:AnyObject] and copy the value only if it's [String:Any]:
if let dict = object as? [String:Any] {
var objDict: [String:AnyObject] = [:]
for (key, value) in dict {
if let obj = value as? AnyObject {
objDict[key] = obj
}
}
return self.parseDict(objDict)
I don't particularly like this, but so far it's be best I've been able to come up with.
Does anyone have any idea how to handle this properly? I'm especially concerned that I can cast Any as [String:AnyObject], pass it to a function that takes [String:Any] and I get no compiler errors, even though it crashes at runtime.