I can't find a solution for the fact that the line with: "CNContactVCardSerialization" keeps throwing an error. Any ideas on what can be wrong here and/or how to fix it? Getting the array with CNContacts works ok.
let contactStore = CNContactStore()
var contacts = [CNContact]()
var vcardFromContacts = NSData()
let fetchRequest = CNContactFetchRequest(keysToFetch:[CNContactVCardSerialization.descriptorForRequiredKeys()])
do{
try contactStore.enumerateContacts(with: fetchRequest, usingBlock: {
contact, cursor in
contacts.append(contact)})
} catch {
print(">>>[ERROR] Unable to get contacts: \(error)")
}
// Returns the vCard representation of the specified contacts
print(">>>[INFO ] Number of contacts found: \(contacts.count)")
do {
try vcardFromContacts = CNContactVCardSerialization.data(with: contacts) as NSData
} catch {
print(">>>[ERROR] Unable to create Vcard information: \(error)")
}
Related
I am currently trying to download, parse and print JSON from an URL.
So far I got to this point:
1) A class (JSONImport.swift), which handles my import:
var data = NSMutableData();
let url = NSURL(string:"http://headers.jsontest.com");
var session = NSURLSession.sharedSession();
var jsonError:NSError?;
var response : NSURLResponse?;
func startConnection(){
let task:NSURLSessionDataTask = session.dataTaskWithURL(url!, completionHandler:apiHandler)
task.resume();
self.apiHandler(data,response: response,error: jsonError);
}
func apiHandler(data:NSData?, response:NSURLResponse?, error:NSError?)
{
do{
let jsonData : NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary;
print(jsonData);
}
catch{
print("API error: \(error)");
}
}
My problem is, that the data in
do{
let jsonData : NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary;
print(jsonData);
}
remains empty.
When I debug,the connection starts successfully, with the given url as a parameter. But my jsonData variable doesn't get printed. Instead the catch block throws the error, stating that there is no data in my variable:
API error: Error Domain=NSCocoaErrorDomain Code=3840 "No value."
Can someone please help me with this?
What am I missing?
Thank you all very much in advance!
[Edited after switching from NSURL Connection to NSURLSession]
Here's an example on how to use NSURLSession with a very convenient "completion handler".
This function contains the network call and has the "completion handler" (a callback for when the data will be available):
func getDataFrom(urlString: String, completion: (data: NSData)->()) {
if let url = NSURL(string: urlString) {
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithURL(url) { (data, response, error) in
// print(response)
if let data = data {
completion(data: data)
} else {
print(error?.localizedDescription)
}
}
task.resume()
} else {
// URL is invalid
}
}
You can use it like this, inside a new function, with a "trailing closure":
func apiManager() {
getDataFrom("http://headers.jsontest.com") { (data) in
do {
let json = try NSJSONSerialization.JSONObjectWithData(data, options: [])
if let jsonDict = json as? NSDictionary {
print(jsonDict)
} else {
// JSON data wasn't a dictionary
}
}
catch let error as NSError {
print("API error: \(error.debugDescription)")
}
}
}
I'm currently developing my first iOS app using Swift 2.0 and Xcode Beta 2. It reads an external JSON and generates a list in a table view with the data. However, I'm getting a strange little error that I can't seem to fix:
Extra argument 'error' in call
Here is a snippet of my code:
let task = session.dataTaskWithURL(url!, completionHandler: {data, response, error -> Void in
print("Task completed")
if(error != nil){
print(error!.localizedDescription)
}
var err: NSError?
if let jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as? NSDictionary{
if(err != nil){
print("JSON Error \(err!.localizedDescription)")
}
if let results: NSArray = jsonResult["results"] as? NSArray{
dispatch_async(dispatch_get_main_queue(), {
self.tableData = results
self.appsTableView!.reloadData()
})
}
}
})
The error is thrown at this line:
if let jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as? NSDictionary{
Can someone please tell me what I'm doing wrong here?
With Swift 2, the signature for NSJSONSerialization has changed, to conform to the new error handling system.
Here's an example of how to use it:
do {
if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? NSDictionary {
print(jsonResult)
}
} catch let error as NSError {
print(error.localizedDescription)
}
With Swift 3, the name of NSJSONSerialization and its methods have changed, according to the Swift API Design Guidelines.
Here's the same example:
do {
if let jsonResult = try JSONSerialization.jsonObject(with: data, options: []) as? [String:AnyObject] {
print(jsonResult)
}
} catch let error as NSError {
print(error.localizedDescription)
}
Things have changed in Swift 2, methods that accepted an error parameter were transformed into methods that throw that error instead of returning it via an inout parameter. By looking at the Apple documentation:
HANDLING ERRORS IN SWIFT:
In Swift, this method returns a nonoptional result and is marked with the throws keyword to indicate that it throws an error in cases of failure.
You call this method in a try expression and handle any errors in the catch clauses of a do statement, as described in Error Handling in The Swift Programming Language (Swift 2.1) and Error Handling in Using Swift with Cocoa and Objective-C (Swift 2.1).
The shortest solution would be to use try? which returns nil if an error occurs:
let message = try? NSJSONSerialization.JSONObjectWithData(receivedData, options:.AllowFragments)
if let dict = message as? NSDictionary {
// ... process the data
}
If you're also interested into the error, you can use a do/catch:
do {
let message = try NSJSONSerialization.JSONObjectWithData(receivedData, options:.AllowFragments)
if let dict = message as? NSDictionary {
// ... process the data
}
} catch let error as NSError {
print("An error occurred: \(error)")
}
This has been changed in Swift 3.0.
do{
if let responseObj = try JSONSerialization.jsonObject(with: results, options: .allowFragments) as? NSDictionary{
if JSONSerialization.isValidJSONObject(responseObj){
//Do your stuff here
}
else{
//Handle error
}
}
else{
//Do your stuff here
}
}
catch let error as NSError {
print("An error occurred: \(error)") }
I have tried the conversion tools to update these few lines of code, but unfortunately the process did not caught up these two errors.
Could you help me to understand if I need to introduce the do { and error handling? (I am new to swift!).
The error message I receive is the following: "Call can throw, but it is not marked with 'try' and the error is not handled"
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
query.findObjectsInBackgroundWithBlock {(result: [PFObject]?, error: NSError?) -> Void in
self.posts = result as? [Post] ?? []
// 1
for post in self.posts {
// 2
let data = post.imageFile?.getData() --> this is where I get the error message
// 3
post.image = UIImage(data: data!, scale:1.0)
}
self.tableview.reloadData()
}
Insted of this: let data = post.imageFile?.getData()
Use this instead:
do
{
try let data = post.imageFile?.getData()
}
catch
{
print("Error: \(error)")
//Handle the error instead of print probably
}
I want to convert the friend list ids that I am getting from facebook as an array to save in parse. My code is as below but I am getting a "unexpectedly found nil while unwrapping an Optional value" error. What should I do to save the result to parse and retrieve it as array when required?
let fbRequest = FBSDKGraphRequest(graphPath:"/me/friends", parameters: nil);
fbRequest.startWithCompletionHandler { (connection : FBSDKGraphRequestConnection!, result : AnyObject!, error : NSError!) -> Void in
if error == nil {
print("Friends are : \(result)")
if let dict = result as? Dictionary<String, AnyObject>{
let profileName:NSArray = dict["name"] as AnyObject? as! NSArray
let facebookID:NSArray = dict["id"] as AnyObject? as! NSArray
print(profileName)
print(facebookID)
}
}
else {
print("Error Getting Friends \(error)");
}
}
When I use the code below in print() I get the result below:
Friends are : {
data = (
{
id = 138495819828848;
name = "Michael";
},
{
id = 1105101471218892;
name = "Johnny";
}
);
The issue is that you are trying to access the name and id elements from the top-level dictionary, where you need to be accessing data.
When you call the FB Graph API for friends it will return an array of dictionaries (one per friend).
Try this:
let fbRequest = FBSDKGraphRequest(graphPath:"/me/friends", parameters: nil)
fbRequest.startWithCompletionHandler { (connection : FBSDKGraphRequestConnection!, result : AnyObject!, error : NSError!) -> Void in
if error == nil {
print("Friends are : \(result)")
if let friendObjects = result["data"] as? [NSDictionary] {
for friendObject in friendObjects {
println(friendObject["id"] as NSString)
println(friendObject["name"] as NSString)
}
}
} else {
print("Error Getting Friends \(error)");
}
}
You should also check out this SO post with more information on the FB Graph API. Here's a brief snippet.
In v2.0 of the Graph API, calling /me/friends returns the person's
friends who also use the app.
In addition, in v2.0, you must request the user_friends permission
from each user. user_friends is no longer included by default in every
login. Each user must grant the user_friends permission in order to
appear in the response to /me/friends. See the Facebook upgrade guide
for more detailed information, or review the summary below.
I am trying to print out the value "username" from my coredata entity.
var request = NSFetchRequest(entityName: "Users")
request.returnsObjectsAsFaults = false
var results = context.executeFetchRequest(request, error: nil)
if (results?.count > 0) {
for result: AnyObject in results! {
println(result.username)
}
}
The line println(result.username) is giving me a compile error of 'AnyObject' does not have a member named 'username'.
You have to cast the array of managed object to the correct type:
for result in results! as [Users] {
println(result.username)
}
This assumes that you have created a managed object subclass for the "Users" entity.
You should also distinguish whether executeFetchRequest() returned nil
(i.e. the fetch request failed), or 0 (i.e. no objects found),
and use the error parameter:
var error : NSError?
if let results = context.executeFetchRequest(request, error: &error) {
if (results.count > 0) {
for result in results as [Users] {
println(result.username)
}
} else {
println("No Users")
}
} else {
println("Fetch failed: \(error)")
// Handle error ...
}
Update for Swift 2/Xcode 7 with try/catch error handling:
do {
let results = try context.executeFetchRequest(request) as! [Users]
if (results.count > 0) {
for result in results {
print(result.username)
}
} else {
print("No Users")
}
} catch let error as NSError {
// failure
print("Fetch failed: \(error.localizedDescription)")
}
Note that the forced cast as! [Users] is acceptable here.
The returned objects are always instances of the corresponding class as configured in the Core Data model inspector, otherwise you have
a programming error which should be detected early.
Martin's answer definitely lets you access the properties of your object, but the cast is forced. Like it or not, Swift's strong type system is the future. When returning results from a fetch request, you might consider testing for the type.
func executeFetchRequestT<T:AnyObject>(request:NSFetchRequest, managedObjectContext:NSManagedObjectContext, error: NSErrorPointer = nil) -> [T]? {
var localError: NSError? = nil
if let results:[AnyObject] = managedObjectContext.executeFetchRequest(request, error: &localError) {
if results.count > 0 {
if results[0] is T {
let casted:[T] = results as [T]
return .Some(casted)
}
if error != nil {
error.memory = NSError(domain: "error_domain", code: 0, userInfo: [NSLocalizedDescriptionKey: "Object in fetched results is not the expected type."])
}
} else if 0 == results.count {
return [T]() // just return an empty array
}
}
if error != nil && localError != nil {
error.memory = localError!
}
return .None
}
Using this approach you can type your results and get an error if the type is incorrect.
var fetchError:NSError? = nil
if let results:[Users] = executeFetchRequestT(fetchRequest, managedObjectContext: managedObjectContext, error: &fetchError) {
for user in results {
// access the results with confidence of the correct type
}
} else {
// should have an error condition, handle it appropriately
assertFailure("something bad happened")
}
Change your for loop to this
for result: AnyObject in results! {
if let user: AnyObject = result.valueForKey("username") {
println(user)
}
}
The fix is using valueForKey("String")