I've a problem with accessing a specific (or any) key in a CFDictionary.
Honestly I don't really get the way you need to do this in Swift and I think it's overly complicated...
My Code:
if let session = DASessionCreate(kCFAllocatorDefault) {
let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: [], options: [])!
for volume in mountedVolumes {
if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL) {
let diskinfo = DADiskCopyDescription(disk);
var volumeValue = CFDictionaryGetValue(diskinfo, <#T##key: UnsafeRawPointer!##UnsafeRawPointer!#>)
}
}
What I want to achieve: Get the Value for the Key or field DAVolumeNetwork into the variable volumeValue.
I guess I need to pass the kDADiskDescriptionVolumeNetworkKey to the CFDictionaryGetValue Method? How do I achieve this?
Don't use CFDictionary in Swift. (It is possible, but not worth the effort, see below.)
CFDictionary is toll-free
bridged with NSDictionary, which in turn can be cast to a Swift Dictionary.
The value of the kDADiskDescriptionVolumeNetworkKey key is a
CFBoolean which can be cast to a Swift Bool.
Example:
if let session = DASessionCreate(kCFAllocatorDefault),
let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: []) {
for volume in mountedVolumes {
if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL),
let diskinfo = DADiskCopyDescription(disk) as? [NSString: Any] {
if let networkValue = diskinfo[kDADiskDescriptionVolumeNetworkKey] as? Bool {
print(networkValue)
}
}
}
}
Just for the sake of completeness: This is the necessary pointer
juggling to call CFDictionaryGetValue in Swift 3:
if let session = DASessionCreate(kCFAllocatorDefault),
let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: []) {
for volume in mountedVolumes {
if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL),
let diskinfo = DADiskCopyDescription(disk) {
if let ptr = CFDictionaryGetValue(diskinfo, Unmanaged.passUnretained(kDADiskDescriptionVolumeNetworkKey).toOpaque()) {
let networkValue = Unmanaged<NSNumber>.fromOpaque(ptr).takeUnretainedValue()
print(networkValue.boolValue)
}
}
}
}
You can cast CFDictionaryRef to a Swift dictionary:
if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL), let diskinfo = DADiskCopyDescription(disk) as? [String: AnyObject] {
}
and then cast kDADiskDescriptionVolumeNetworkKey to a Swift string:
var volumeValue = diskinfo[kDADiskDescriptionVolumeNetworkKey as String]
Related
until version 10.7.6 of Realm I could convert to dictionary and then to json with this code below, but the ListBase class no longer exists.
extension Object {
func toDictionary() -> NSDictionary {
let properties = self.objectSchema.properties.map { $0.name }
let dictionary = self.dictionaryWithValues(forKeys: properties)
let mutabledic = NSMutableDictionary()
mutabledic.setValuesForKeys(dictionary)
for prop in self.objectSchema.properties as [Property] {
// find lists
if let nestedObject = self[prop.name] as? Object {
mutabledic.setValue(nestedObject.toDictionary(), forKey: prop.name)
} else if let nestedListObject = self[prop.name] as? ListBase { /*Cannot find type 'ListBase' in scope*/
var objects = [AnyObject]()
for index in 0..<nestedListObject._rlmArray.count {
let object = nestedListObject._rlmArray[index] as! Object
objects.append(object.toDictionary())
}
mutabledic.setObject(objects, forKey: prop.name as NSCopying)
}
}
return mutabledic
}
}
let parameterDictionary = myRealmData.toDictionary()
guard let postData = try? JSONSerialization.data(withJSONObject: parameterDictionary, options: []) else {
return
}
List now inherits from RLMSwiftCollectionBase apparently, so you can check for that instead. Also, this is Swift. Use [String: Any] instead of NSDictionary.
extension Object {
func toDictionary() -> [String: Any] {
let properties = self.objectSchema.properties.map { $0.name }
var mutabledic = self.dictionaryWithValues(forKeys: properties)
for prop in self.objectSchema.properties as [Property] {
// find lists
if let nestedObject = self[prop.name] as? Object {
mutabledic[prop.name] = nestedObject.toDictionary()
} else if let nestedListObject = self[prop.name] as? RLMSwiftCollectionBase {
var objects = [[String: Any]]()
for index in 0..<nestedListObject._rlmCollection.count {
let object = nestedListObject._rlmCollection[index] as! Object
objects.append(object.toDictionary())
}
mutabledic[prop.name] = objects
}
}
return mutabledic
}
}
Thanks to #Eduardo Dos Santos. Just do the following steps. You will be good to go.
Change ListBase to RLMSwiftCollectionBase
Change _rlmArray to _rlmCollection
Import Realm
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 have a Realm database called NewsCount. I need to download a new news only if there is a new news (respectively when newsCount change). And I make a comparison with the data parsing. But I can not compare them properly. How do you compare them?
Thi is my code
private func parseJSONData(_ data: Data) {
do {
let temp: NSString = NSString(data: data, encoding: String.Encoding.utf8.rawValue)!
let myNSData = temp.data(using: String.Encoding.utf8.rawValue)!
guard let jsonResult = try JSONSerialization.jsonObject(with: myNSData, options: JSONSerialization.ReadingOptions.mutableContainers) as? NSDictionary else {
return
}
guard let jsonNews = jsonResult["categories"] as? [AnyObject] else {
print("Empty array")
return
}
let realm = try Realm()
let category = realm.objects(NewsCount.self)
var array = [Int]()
for i in category {
array.append(i.newsCount)
}
print(array)
print("News COUNT2 \(category)")
for jsonnewes in jsonNews {
let newsJson = NewsCount()
//HERE I COMPARE
if !UserDefaults.standard.bool(forKey: "AppStarted") || jsonnewes["count"] as! Int > array[jsonnewes as! Int]{
newsJson.newsID = jsonnewes["term_id"] as! Int
newsJson.newsCount = jsonnewes["count"] as! Int
//print("News COUNT2 \(newsJson.newsCount)")
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "downloadNew"), object: nil)
} else {
newsJson.newsID = jsonnewes["term_id"] as! Int
newsJson.newsCount = jsonnewes["count"] as! Int
//print("News COUNT3 \(newsJson.newsCount)")
}
insertOrUpdate(newsJson)
}
} catch {
print(error)
}
}
Because Realm uses RealmOptional to use Int values you have to call the value atribute to the RealmOptional
Try change this:
for i in category {
array.append(i.newsCount.value)
}
First off, it's probably more appropriate to use Int(string) instead of as! Int force-casting to convert your JSON data to integers.
From the looks of it, jsonnewes is a dictionary full of JSON data, but you're casting it as an array index in array[jsonnewes as! Int] which (given array is an array and not a dictionary) shouldn't work.
Instead, in order to make sure you're explicitly retrieving the item you want, I'd recommend using Realm's primary key query method in order to retrieve the item you want.
let realm = try! Realm()
for newsItem in jsonNews {
let newsPrimaryKey = Int(newsItem)
let realmNews = realm.object(ofType: NewsCount.self, forPrimaryKey: newsPrimaryKey)
// Don't continue if a Realm object couldn't be found
guard let realmNews = realmNews else {
continue
}
// Perform comparison
if Int(newsItem["count"]) > realmNews.newsCount {
// Perform the update
}
}
I have this code:
var address = Dictionary<String, AnyObject?>();
address["address1"] = "Here";
address["address2"] = "There";
...
let defaults = NSUserDefaults.standardUserDefaults();
var data = defaults.valueForKey("active_user")! as! Dictionary<String, AnyObject?>
data["address"] = address;
defaults.setValue(data, forKey: "active_user");
defaults.synchronize();
I want to change it into like this:
var address = Dictionary<String, AnyObject?>();
address["address1"] = "Here";
address["address2"] = "There";
...
let defaults = NSUserDefaults.standardUserDefaults();
defaults["active_user"]!["address"]! = address;
defaults.synchronize();
Is this possible? How can I do that?
This is somewhat possible by extending NSUserDefaults to have a subscript. See below:
extension NSUserDefaults {
subscript(key: String) -> Any {
get {
return value(forKey: key)
}
set {
setValue(newValue, forKey: key)
}
}
}
This can then be used like so:
let defaults = NSUserDefaults.standardUserDefaults()
defaults["myKey"] = "someValue"
let myValue = defaults["myKey"]
One limitation is that you won't be able to modify nested collections as you've done in your example. You'll always have to make a manual assignment back to the user defaults object to save something.
// this won't work
defaults["active_user"]!["address"]! = address;
// do this instead
let user = defaults["active_user"]!
user["address"] = address
defaults["active_user"] = user
Edit:
I figured out a way to overload the subscript so you can modify nested collections, with slightly different but very clean syntax. Only works at one level of nesting, but I think it could be taken further. Add this to your NSUserDefaults extension:
subscript(firstKey: String, secondKey: String) -> Any? {
get {
if let dict = value(forKey: firstKey) as? [String: Any] {
return dict[secondKey]
}
return nil
}
set {
if let dict = value(forKey: firstKey) as? [String: Any] {
dict[secondKey] = newValue
setValue(dict, forKey: firstKey)
}
}
}
Then you can do this:
defaults["active_user", "address"] = "some address"
let address = defaults["active_user", "address"]
Hi I retrived value from JSON and stored in NSMutableArray. I have tried this like Singleton. I have used empty swift file for this. Datas successfully retrieved and stored in NSMutableArray which is already declared in mainViewController. Then, if I use that NSMutableArray value in mainViewController, it shows empty array.
My coding is below. Kindly guide me.
Empty Swift File
public class json_file{
var prod_Obj = product_mainVC()
class var shared: json_file
{
struct Static
{
static let instance: json_file = json_file()
}
return Static.instance
}
func dataFromJSON()
{
let url = NSURL(string: "http://........--...4900a20659")!
var data : NSData = NSData(contentsOfURL: url, options: NSDataReadingOptions.DataReadingMapped, error: nil)!
var dict: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
let dataArray = dict["data"] as [[String:AnyObject]] // The array of dictionaries
for object in dataArray {
let category_name = object["category_name"] as String
prod_Obj.ct_name_arr.addObject(category_name)
let category_child = object["category_child"] as [[String:AnyObject]]
for child in category_child {
let sub_category_name = child["sub_category_name"] as String
prod_Obj.sub_ct_name_arr.addObject(sub_category_name)
}
}
println(prod_Obj.ct_name_arr) //Here value is Getting
println(prod_Obj.sub_ct_name_arr) //Here value is Getting
}
}
viewDidLoad
{
json_file.shared.dataFromJSON()
println(ct_name_arr) //Prints Empty Array [Intially Declared as NSMutableArray]
println(sub_ct_name_arr) //Prints Empty Array [Intially Declared as NSMutableArray]
}
I was trying understand the problem, but I can't see the product_mainVC. Because this I remake your class with little modifications.
class JsonFile
{
private(set) var categoryNames:[String];
private(set) var subCategoryNames:[String];
class let shared:JsonFile = JsonFile();
private init()
{
self.categoryNames = [];
self.subCategoryNames = [];
}
func dataFromJson()
{
let url = NSURL(string: "http://........--...4900a20659")!
if let data : NSData = NSData(contentsOfURL: url, options: NSDataReadingOptions.DataReadingMapped, error: nil)
{
if let dict: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as? NSDictionary
{
if let dataArray = dict["data"] as? [[String:AnyObject]] // The array of dictionaries
{
for object in dataArray {
let category_id = object["category_id"] as Int
let category_name = object["category_name"] as String
categoryNames.append(category_name);
let category_child = object["category_child"] as [[String:AnyObject]]
for child in category_child {
let sub_category_id = child["sub_category_id"] as Int
let sub_category_name = child["sub_category_name"] as String
subCategoryNames.append(sub_category_name);
}
}
}
}
}
println(categoryNames);
println(subCategoryNames);
}
}
I did
Modify your way to do Singleton to a safe and more simple mode, create the arrays categoryNames and subCategoryNames internal in class because this is better to manipulate, and protect your fetch data to safe from possibles crash.
Implementation
JsonFile.shared.dataFromJson();
println("count categoryNames");
println(JsonFile.shared.categoryNames.count);
println("count subCategoryNames");
println(JsonFile.shared.subCategoryNames.count);
You need think about
This code is sync, and because this if you have a big data or request slow, the main thread from your application will freeze waiting return and it is bad for your user. Think if is necessary be sync.
let category_id = object["category_id"] as Int is never used. Why do you stay with this in code?