I have two arrays.
var searchedArray: NSMutableArray!
var libraryArray: NSMutableArray!
I'm trying to fix my searchBar functionality because it always shows nil(searchedArray = nil).
I've tried to downcast it in different ways but it doesn't work.
Here's the snippet.
let laMutableCopy = (downloadManager.libraryArray as NSArray).mutableCopy()
searchedArray = laMutableCopy.filter{
guard let dict = $0 as? Dictionary<String, Any> else {return false}
guard let title = dict["title"] as? String else {return false}
return title.range(of: searchText, options: [caseInsensitive, .anchored]) != nil
} as? NSMutableArray
Here's an example that would work:
var libraryArray = [
["title": "foo"],
["title": "bar"]
]
var filteredArray = libraryArray.filter{
// your production code doesn't have to be like this, but when attempting to debug
// its very helpful to break each cast out into its own assign to see where you
// are failing
guard let dict = $0 as? Dictionary<String, Any> else { return false }
guard let title = dict["title"] as? String else { return false }
return title.range(of: "fo", options: [.caseInsensitive, .anchored]) != nil
} as? Array<Dictionary<String, Any>>
The problem with your code is that you're casting the result of the filter (a swift Array) to an NSMutableArray. Swift arrays can be cast to NSArray, but they cannot be cast to NSMutableArray without constructing a copy like so:
(libraryArray as NSArray).mutableCopy()
Related
Tried the 'is' keyword.
// Initialize the dictionary
let dict = ["name":"John", "surname":"Doe"]
// Check if 'dict' is a Dictionary
if dict is Dictionary {
print("Yes, it's a Dictionary")
}
This will give an error saying "'is' is always true".
I just want to check if an object is a dictionary. It can be with any key any value pairs.
The key is hashable and it is not accepting the Any keyword.
If you want to check if an arbitrary object is a dictionary first of all you have to make the object unspecified:
let dict : Any = ["name":"John", "surname":"Doe"]
Now you can check if the object is a dictionary
if dict is Dictionary<AnyHashable,Any> {
print("Yes, it's a Dictionary")
}
But this way is theoretical and only for learning purposes. Basically it's pretty silly to cast up a distinct to an unspecified type.
If you just want to check if your object is Dictionary you can just do this:
if let dictionary = yourObject as? Dictionary{
print("It is a Dictionary")
}
Put this in a playground:
import UIKit
// Create a dictionary and an array to convert to and from JSON
let d = ["first": "Goodbye", "second": "Hello"]
let a = [1, 2, 3, 4, 5]
let dictData = try! JSONSerialization.data(withJSONObject: d, options: [])
let arrayData = try! JSONSerialization.data(withJSONObject: a, options: [])
// Now that we have set up our test data, lets see what we have
// First, some convenience definitions for the way JSON comes across.
typealias JSON = Any
typealias JSONDictionary = [String: JSON]
typealias JSONArray = [JSON]
// Lets see what we have
let dict = try! JSONSerialization.jsonObject(with: dictData, options: [])
let array = try! JSONSerialization.jsonObject(with: arrayData, options: [])
// testing functions
func isDictionary(_ object: JSON) -> Bool {
return ((object as? JSONDictionary) != nil) ? true : false
}
func isArray(_ object: JSON) -> Bool {
return ((object as? JSONArray) != nil) ? true : false
}
// The actual tests
isDictionary(dict) // true
isArray(dict) // false
isDictionary(array)// false
isArray(array) // true
JSON dictionaries arrays have specific types
I prefer using if let or guard let while parsing JSON objects
if let dict = jsonObject as? [AnyHashable:Any] {
print("Yes, it's a Dictionary")
}
guard let dict = jsonObject as? [AnyHashable:Any] else {
print("No, it's not a Dictionary")
return
}
Simply use is operator to check type conformance.
Here's a little snippet where I check if it's a Dictionaryor an Array
let dict = ["name":"John", "surname":"Doe"]
let array = [ "John", "Doe" ]
if dict is Dictionary<String, String>
{
print("Yes, it's a Dictionary")
}
else
{
print("No, It's other thing")
}
if array is Array<String>
{
print("Yes, it's a Array")
}
else
{
print("No, It's other thing")
}
I am trying to parse the emergency data in into emergency struct but it never statifies the condition and get into else case.Here is my code and structure.Some thing i have written woring in first line.
if let emergencyDict = snapshotValue["emergency"] as? [String:[String:Any]]{
for (emerId, emerData) in emergencyDict {
let emer = Emergency.init(emergency: emerData as NSDictionary)
emergency.append(emer)
}
}
else{
let emer = Emergency.init(emerg: "" as AnyObject)
emergency.append(emer)
}
struct Emergency{
var emer_id: String
var emer_name: String
var emer_phoneNo: String
init(emergency: NSDictionary) {
if emergency.object(forKey: "id") != nil {
emer_id = emergency.object(forKey: "id") as! String
}
else{
emer_id = ""
}
}
}
The problem you are having emergency as Array with type [Any] and if you remove the first object then you get Array of type [[String:Any]]. So try like this way.
if let array = snapshotValue["emergency"] as? [Any],
let emergencyArrar = Array(array.dropFirst()) as? [[String:Any]] {
print(emergencyArray)
for emergency in emergencyArray {
print(emergency)
}
}
You have written wrong in this line:
if let emergencyDict = snapshotValue["emergency"] as? [String:[String:Any]]{
It should be:
if let emergencyDict = snapshotValue["emergency"] as? [[String:Any]]{
This question should belong to query from firebase database.
// you have to get the children in emergency,
// then get the value(dictionary) of each child
ref.child("emergency").observeSingleEvent(of: .value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
let keys = value?.allKeys // [1, 2, 3 ....]
for key in keys {
ref.child("emergency").child(key)..observeSingleEvent(of: .value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
// Here is your dictionary
}
}
}) { (error) in
print(error.localizedDescription)
}
I am fairly new to the Swift syntax and am receiving this error with my code "Cannot assign through subscript: subscript is get only"
This is from the line: friendDictionary[(friendUID as? String)!] = ["name": friendsData!["name"]]
Any advice on the correct way of doing it would be very helpful.
func getFriendsUIDs() {
if FBSDKAccessToken.currentAccessToken() == nil {
print("failed to start graph request")
return
}else{
}
if FBSDKAccessToken.currentAccessToken() != nil {
}
let parameters = ["fields": "name, id, picture"]
FBSDKGraphRequest(graphPath: "/me/friends", parameters: parameters).startWithCompletionHandler {
(NSURLConnection, result, requestError) in
let friendIds = result["id"] as? NSDictionary
let friendsData = friendIds!["data"] as? [NSDictionary]
var ref: FIRDatabaseReference!
ref = FIRDatabase.database().reference()
ref.child("users").child((FIRAuth.auth()?.currentUser?.uid)!).child("friendUIDs").observeEventType(.Value, withBlock: { (snapshot) in
self.FriendUIDs = NSArray()
self.FriendUIDs = (snapshot.value as? NSArray)!
print(self.FriendUIDs)
var friendDictionary = NSDictionary()
for friendUID in self.FriendUIDs {
friendDictionary[(friendUID as? String)!] = ["name": friendsData!["name"]]
}
self.fetchFriendFeed(friendDictionary)
}) { (error) in
print(error.localizedDescription)
}
}
}
func fetchFriendFeed(friendDictionary: NSDictionary) {
var ref: FIRDatabaseReference!
ref = FIRDatabase.database().reference()
for friendUID in FriendUIDs {
ref.child("users").child(friendUID as! String).child("Agenda").observeEventType(.ChildAdded, withBlock: { (snapshot) in
print(snapshot)
if let dictionary = snapshot.value as? [String: AnyObject] {
let friendPost = FriendPost()
friendPost.picture = friendDictionary[friendUID as! String]? ["picture"] as? String
friendPost.activity = dictionary["activity"] as? String
friendPost.date = dictionary["date"] as? String
friendPost.time = dictionary["time"] as? String
friendPost.friendname = friendDictionary[friendUID as! String]? ["name"] as? String
self.friendPosts.append(friendPost)
dispatch_async(dispatch_get_main_queue(), {
self.collectionView?.reloadData()
Nothing to do with Swift. You've elected to use Objective-C, in effect, by making friendDictionary an NSDictionary. NSDictionary is immutable; you can't assign into it or alter it in any way. That is simply a fact about Objective-C. The Swift var declaration makes no difference to this fact.
A better choice, since you are writing in Swift, would be to use a Swift dictionary, which is [AnyHashable:Any]() (in Swift 3). This will interchange with NSDictionary when you are talking to Objective-C, but it will give you a mutable dictionary because you (rightly) declared it with var.
Have you tried using NSMutableDictionary? That solved the issue for me.
For those who get stuck here, another reason for this happens when you try to assign something that does not conform the actual dictionary, in my example i was doing something like this:
var dict = [Date : UUID]()
let randomUUID = UUID()
dict[randomUUID] = Date.now
whereas I meant to write UUID : Date but I was sleepy so i made a mistake, and Swift gave me a misleading error saying subscript is get-only. So this error also appears with type mismatch for Swift 5.7.
I am not an iOS dev and have to make a few changes to a Swift / AlamoFire project (not mine) and am a bit lost.
I have the following JSON:
{"metro_locations":
[
{
"name":"Ruby Red"
},
{
"name":"Blue Ocean"
}
]
}
class (I know that there are issues here):
class Location{
var name=""
init(obj:tmp){
self.name=tmp["name"]
}
}
and need to make an AlamoFire call
Alamofire.request(.GET, "https://www.domain.com/arc/v1/api/metro_areas/1", parameters: nil)
.responseJSON { response in
if let dataFromNetworking = response.result.value {
let metroLocations = dataFromNetworking["metro_locations"]
var locations: [Location]=[]
for tmp in metroLocations as! [Dictionary] { // <- not working, Generic Paramter 'Key' could not be inferred
let location=Location.init(obj: tmp)
locations.append(location)
}
}
}
I have included the error msg, the "not working" but feel that there are issues in other parts too (like expecting a dictionary in the initialization). What does the 'Key' could not be inferred mean and are there other changes I need to make?
edit #1
I have updated my Location to this to reflect your suggestion:
init?(dictionary: [String: AnyObject]) {
guard let id = dictionary["id"] else { return nil }
guard let name = dictionary["name"] else { return nil }
guard let latitude = dictionary["latitude"] else { return nil }
guard let longitude = dictionary["longitude"] else { return nil }
self.name = name as! String
self.id = id as! Int
self.latitude = latitude as! Double
self.longitude = longitude as! Double
}
but I get the error:
Could not cast value of type 'NSNull' (0x10f387600) to 'NSNumber' (0x10f77f2a0).
like this:
I would think that the guard statement would prevent this. What am I missing?
You can cast metroLocations as an array of dictionaries, namely:
Array<Dictionary<String, String>>
Or, more concisely:
[[String: String]]
Thus:
if let dataFromNetworking = response.result.value {
guard let metroLocations = dataFromNetworking["metro_locations"] as? [[String: String]] else {
print("this was not an array of dictionaries where the values were all strings")
return
}
var locations = [Location]()
for dictionary in metroLocations {
if let location = Location(dictionary: dictionary) {
locations.append(location)
}
}
}
Where
class Location {
let name: String
init?(dictionary: [String: String]) {
guard let name = dictionary["name"] else { return nil }
self.name = name
}
}
Clearly, I used [[String: String]] to represent an array of dictionaries where the values were all strings, as in your example. If the values included objects other than strings (numbers, booleans, etc.), then you might use [[String: AnyObject]].
In your revision, you show us a more complete Location implementation. You should avoid as! forced casting, and instead us as? in the guard statements:
class Location {
let id: Int
let name: String
let latitude: Double
let longitude: Double
init?(dictionary: [String: AnyObject]) {
guard let id = dictionary["id"] as? Int,
let name = dictionary["name"] as? String,
let latitude = dictionary["latitude"] as? Double,
let longitude = dictionary["longitude"] as? Double else {
return nil
}
self.name = name
self.id = id
self.latitude = latitude
self.longitude = longitude
}
}
I want to safely search through values in a swift Dictionary using if lets and making sure it is type safe as I get deeper and deeper into the dictionary. The dictionary contains dictionaries that contains NSArray that contains more dictionary.
At first attempt my code looks like this:
if let kkbox = ticket["KKBOX"] as? Dictionary<String, AnyObject> {
if let kkboxDlUrlDict = kkbox["kkbox_dl_url_list"] as? Dictionary<String, AnyObject> {
if let kkboxDlUrlArray = kkboxDlUrlDict["kkbox_dl_url"] as? NSArray {
for dict in kkboxDlUrlArray {
if let name = dict["name"] as? String {
if name == mediaType.rawValue {
urlStr = dict["url"] as String
}
}
}
} else { return nil }
} else { return nil }
} else { return nil }
How do I shorten it to perhaps one or 2 line?
I realised I can chain it if it is 2 layers. This works:
if let kkboxDlUrlArray = ticket["KKBOX"]?["kkbox_dl_url_list"] as? NSArray {
}
But any chain longer than that, will not compile.
Is there a way to chain through a dictionary more than once?
Thank you
You can chain, but with proper downcast at each step:
if let kkboxDlUrlArray = ((((ticket["KKBOX"] as? Dictionary<String, AnyObject>)?["kkbox_dl_url_list"]) as? Dictionary<String, AnyObject>)?["kkbox_dl_url"]) as? NSArray {
for dict in kkboxDlUrlArray {
println(dict)
}
}
That doesn't look good though - it's one line, but not readable.
Personally, without using any fancy functional way to do it, I would make the chain more explicit with just one optional binding:
let kkbox = ticket["KKBOX"] as? Dictionary<String, AnyObject>
let kkboxDlUrlDict = kkbox?["kkbox_dl_url_list"] as? Dictionary<String, AnyObject>
if let kkboxDlUrlArray = kkboxDlUrlDict?["kkbox_dl_url"] as? NSArray {
for dict in kkboxDlUrlArray {
println(dict)
}
}
In my opinion much easier to read, and with no unneeded indentation
Alternatively, you could use this extension, which mimics the original valueForKeyPath method that used to exist in NSDictionary but got axed for whatever reason:
Swift 4.1
extension Dictionary where Key: ExpressibleByStringLiteral {
func valueFor(keyPath: String) -> Any? {
var keys = keyPath.components(separatedBy: ".")
var val : Any = self
while keys.count > 0 {
if let key = keys[0] as? Key {
keys.remove(at: 0)
if let dic = val as? Dictionary<Key, Value> {
if let leaf = dic[key] {
val = leaf
} else {
return nil
}
} else {
return nil
}
} else {
return nil
}
}
return val
}
Your code would then read:
if let array = ticket.valueFor("KKBOX.kkbox_dl_url_list.kkbox_dl_url") as? [] {
// do something with array
}
Seems like swift 1.2 has added this feature.
"More powerful optional unwrapping with if let — The if let construct can now unwrap multiple optionals at once, as well as include intervening boolean conditions. This lets you express conditional control flow without unnecessary nesting."
https://developer.apple.com/swift/blog/