I'm attempting to grab source from a page online to parse it and put the information into an array. The request goes through fine, and html has the source as a string as I would like. The problem is, after this function, even though html and sbcc are global, the values I've added disappear. Even the "Test" in the parse function does not appear. I think it has something to do with the request being asynchronous? I've searched, but it's only brought me to ideas I didn't quite understand, or doesn't really cover my specific question. My code snippets are below, if anyone can help I'd greatly appreciate it.
let url = NSURL(string: "http://www.google.com");
var html = String()
var sbcc = courselisting();
func getSource(url: NSURL){
let request = NSURLRequest(URL: url)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {
(response, data, error) in
if (error != nil) {
println("whoops, something went wrong")
let alert : UIAlertView = UIAlertView(title: "Oops!", message: "Something went wrong", delegate: nil, cancelButtonTitle: "Reload")
alert.show()
} else {
//println(self.html)
self.html = NSString(data: data, encoding: NSUTF8StringEncoding)!
self.parse()
}
}
}
func parse() {
sbcc.subjects.append("Test")
sbcc.subjects.append(html.substringToIndex(advance(html.startIndex, 2)))
println(self.html)
}
EDIT: following zisoft's advice i removed the passing of the html string into parse() in my above code, however my global string html still does not have the appended values. for more info here is the main portion of viewDidLoad
getSource(url!);
println(self.html)
it is printing blank in the viewDidLoad but the println inside of parse prints out the proper HTML.
Parameters are passed by value to functions. So you are appending to a copy of html.
Since you declared html in a global scope there is no need to pass it to the function:
{
...
self.parse()
}
func parse() {
sbcc.subjects.append("Test")
sbcc.subjects.append(html.substringToIndex(advance(html.startIndex, 2)))
println(self.html)
}
I've Solved it! using Rob's answer here. basically I need to do all asynchronous activity WITHIN the asynch call and just have everything refresh when complete.
Related
I’m trying to convert escaping closure code to async-await code in a certain file. I’m stuck with implementing the async-await part, specifically whether to still use a do block, with catch and resume, or to not use a do block, and assign the line of code with “try await URLSession.shared.dataTask(with: request)” (that's commented out in File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift in this post below, and meant to be used in the solution attempts to this file) to a variable, then use that variable later similar to how the file File2-GettingRestaurantBusinessDataUsingAsync-AwaitAndUsingCodable.swift does, which is posted further below in this post.
*Note: I used async-await and codable to get the restaurant business data for a certain searched city (thats searched by the user) which is done in a different file (and function). The file I’m having trouble with though is for getting the selected restaurant business’s detail info (name, address, business hours, etc.), and I’m not using codable in this file because some of the data I get when doing this URL request, I get by using NSDictionary; not codable.
How do I correctly implement this async-await concept in my file? The file I’m implementing this in is File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift which is posted further below in this post.
*Update: Where I thought my problem lied when first writing up this question post: At the line of code “URLSession.shared.dataTask(with: request) { (data, response, error) in” in File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift, specifically I thought that I should use the form of code that didn’t use the completionHandler (which is commented as V2 in that file), and whether to use a do block after it, and catch, and resume after the do block.
I’ve posted some attempted solutions so far, which are incomplete, since I’m having the problems mentioned in the first paragraph of this post. I know they don’t work, but this is my thought process so far. These solution attempts are below the code files that I’m working with which are posted further below.
I used the following article for learning more about async-await before attempting to make this current implementation: https://www.avanderlee.com/swift/async-await/.
My code:
Code files that I’m working with:
File that I’m attempting to implement this escaping closure to async-await concept in:
File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift:
import Foundation
import UIKit
import CoreLocation
extension UIViewController {
func retrieveSelectedRestaurantDetailViewInfo(
selected_restaurant_business_ID: String) async throws -> SelectedRestaurantDetailViewInfoNotUsingCodable? {
// MARK: Make API Call
let apiKey = "API key"
/// Create URL
let baseURL =
"https://api.yelp.com/v3/businesses/\(selected_restaurant_business_ID)"
let url = URL(string: baseURL)
/// Creating Request
var request = URLRequest(url: url!)
request.setValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
request.httpMethod = "GET"
///Initialize session and task
//V1: Code for using escaping closure version code.
URLSession.shared.dataTask(with: request) { (data, response, error) in
//This version commented out right now, to show where I'm at with this proboem for clarity. This version is included in the solution attempts; both SoultionAttempt1 and SolutionAttempt2.
if let error = error {
completionHandler(nil, error)
}
//V2: Code for what I think is correct for using async-await version code. Not using the completionHandler here.
// URLSession.shared.dataTask(with: request)
do {
/// Read data as JSON
let json = try JSONSerialization.jsonObject(with: data!, options: [])
/// Main dictionary
guard let responseDictionary = json as? NSDictionary else {return}
//Code for accessing restaraunt detail view info, and assigning it to selectedRestarauntDetailViewInfo view model thats a struct.
var selectedVenue = SelectedRestaurantDetailViewInfoNotUsingCodable()
//Rest of code for accessing restaraunt detail view info, and assigning it to seelctedRestarauntDetailViewInfo view model thats a struct.
selectedVenue.name = responseDictionary.value(forKey: "name") as? String
//*Rest of code for getting business info including address, hours, etc..*
//Commented out for now, because am going with version 2 below.
//V1: Uses escaping closure code version.
// completionHandler(selectedVenue, nil)
//V2: Used for Async/Await code version.
return selectedVenue
} catch {
print("Caught error")
}
}.resume()
}
}
*Update: Below is the new file that shows the code that calls the function with the URLRequest in it in File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift, that uses the async-await concept, as mentioned in a response to a comment in this post:
File0.5-FileWithJustCodeThatCallsTheFunctionForMakingTheURLRequestInFile1.swift:
async let responseSelectedVenueDetailViewInfoNotUsingCodable = try await retrieveSelectedRestaurantDetailViewInfo(selected_restaurant_business_ID: venues.id)
File (file I'm referring to is below; is File2-GettingRestaurantBusinessDataUsingAsync-AwaitAndUsingCodable.swift) that uses async-await for getting the initial restaurant business data, after the user selects a city, which I’m using for reference for making the stated change from the escaping closure code to the async-await code in File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift above:
File2-GettingRestaurantBusinessDataUsingAsync-AwaitAndUsingCodable.swift:
import UIKit
import Foundation
import CoreLocation
class YelpApiSelectedRestaurantDetailViewInfo {
private var apiKey: String
init(apiKey: String) {
self.apiKey = apiKey
}
func searchBusinessDetailViewInfo(selectedRestaurantBusinessID: String) async throws -> SelectedRestaurantDetailViewInfo {
var resultsForTheSelectedRestaurantDetailViewInfo: SelectedRestaurantDetailViewInfo
// MARK: Make URL Request.
var urlComponents = URLComponents(string: "https://api.yelp.com/v3/businesses/\(selectedRestaurantBusinessID)")
guard let url = urlComponents?.url else {
throw URLError(.badURL)
}
var request = URLRequest(url: url)
request.setValue("Bearer \(self.apiKey)", forHTTPHeaderField: "Authorization")
let (data, _) = try await URLSession.shared.data(for: request)
let businessDetailViewInfoResults = try JSONDecoder().decode(SelectedRestaurantDetailViewInfo.self, from: data)
resultsForTheSelectedRestaurantDetailViewInfo = businessDetailViewInfoResults
return resultsForTheSelectedRestaurantDetailViewInfo
}
}
Solution Attempts:
*Note:
-Both of the below solution attempt code snippets start at the line of code: URLSession.shared.dataTask(with: request) { (data, response, error) in in File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift, and goes through the rest of that file, and ends at the same end point as that file (as file File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift).
-Also, the file that these solution attempts are to be implemented in is File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift.
SolutionAttempt1-DoesntUseDoBlock.swift:
///Initialize session and task
try await URLSession.shared.dataTask(with: request)
/// Read data as JSON
let json = try JSONSerialization.jsonObject(with: data!, options: [])
/// Main dictionary
guard let responseDictionary = json as? NSDictionary else {return}
//Code for accessing restaraunt detail view info, and assigning it to selectedRestarauntDetailViewInfo view model thats a struct.
var selectedVenue = SelectedRestaurantDetailViewInfoNotUsingCodable()
//Rest of code for accessing restaraunt detail view info, and assigning it to seelctedRestarauntDetailViewInfo view model thats a struct.
selectedVenue.name = responseDictionary.value(forKey: "name") as? String
//*Rest of code for getting business info including address, business hours, etc..*
return selectedVenue
} catch {
print("Caught error")
}
}.resume()
}
}
*Note about the following solution attempt file: The solution attempt here in my opinion (SolutionAttempt2-DoesUseDoBlock.swift) may not have to include indentation for the do block, where the do block is within the scope of the “try await URLSession.shared.dataTask(with: request)” line of code, but I included the below solution attempt to have this indentation, as it would seem that the do block would need to be within the scope of the “try await URLSession.shared.dataTask(with: request)” line of code, and the original file version of File1-GettingSelectedRestaurantBusinessDataUsingAsync-AwaitAndNotUsingCodable.swift, that uses the escaping closure (not the file being edited/worked on here) had the do block within the “URLSession.shared.dataTask(with: request) { (data, response, error) in” line of code’s scope, which is at the same position as the “try await URLSession.shared.dataTask(with: request)” line of code in this SolutionAttempt2-DoesUseDoBlock.swift file below.
SolutionAttempt2-DoesUseDoBlock.swift:
///Initialize session and task
try await URLSession.shared.dataTask(with: request)
do {
/// Read data as JSON
let json = try JSONSerialization.jsonObject(with: data!, options: [])
/// Main dictionary
guard let responseDictionary = json as? NSDictionary else {return}
//Code for accessing restaraunt detail view info, and assigning it to seelctedRestarauntDetailViewInfo view model thats a struct.
var selectedVenue = SelectedRestaurantDetailViewInfoNotUsingCodable()
//Rest of code for accessing restaraunt detail view info, and assigning it to seelctedRestarauntDetailViewInfo view model thats a struct.
selectedVenue.name = responseDictionary.value(forKey: "name") as? String
//*Rest of code for getting business info including address, business hours, etc.*
return selectedVenue
} catch {
print("Caught error")
}
}.resume()
}
}
Thanks!
When attempting an http request to my rest api, I continually get a 401 error when using the following code. I don not get this error making any other type of request. I have provided the function that makes the request below.
func deleteEvent(id: Int){
eventUrl.append(String(id))
let request = NSMutableURLRequest(url: NSURL(string: eventUrl)! as URL)
request.httpMethod = "DELETE"
print(eventUrl)
eventUrl.removeLast()
print(self.token!)
request.allHTTPHeaderFields = ["Authorization": "Token \(self.token)"]
let task = URLSession.shared.dataTask(with: request as URLRequest) { data, response, error in
if error != nil {
print("error=\(String(describing: error))")
//put variable that triggers error try again view here
return
}
print("response = \(String(describing: response))")
}
task.resume()
}
When sending the delete request with postman, the rest api just returns the data I want to delete but does not delete it. For reference I have posted the view and permissions classes associated with this request Any help understanding why this may be resulting in an error is greatly appreciated!
Views.py
class UserProfileFeedViewSet(viewsets.ModelViewSet):
"""Handles creating, reading and updating profile feed items"""
authentication_classes = (TokenAuthentication,)
serializer_class = serializers.ProfileFeedItemSerializer
queryset = models.ProfileFeedItem.objects.all()
permission_classes = (permissions.UpdateOwnStatus, IsAuthenticated)
def perform_create(self, serializer):
"""Sets the user profile to the logged in user"""
#
serializer.save(user_profile=self.request.user)
Permissions.py
class UpdateOwnStatus(permissions.BasePermission):
"""Allow users to update their own status"""
def has_object_permission(self, request, view, obj):
"""Check the user is trying to update their own status"""
if request.method in permissions.SAFE_METHODS:
return True
return obj.user_profile.id == request.user.id
HEADER SENT WITH DELETE REQUEST VIA POSTMAN
Preface: You leave out too much relevant information from the question for it to be properly answered. Your Swift code looks, and please don't be offended, a bit beginner-ish or as if it had been migrated from Objective-C without much experience.
I don't know why POSTMAN fails, but I see some red flags in the Swift code you might want to look into to figure out why your iOS app fails.
I first noticed that eventUrl seems to be a String property of the type that contains the deleteEvent function. You mutate it by appending the event id, construct a URL from it (weirdly, see below), then mutate it back again. While this in itself is not necessarily wrong, it might open the doors for racing conditions depending how your app works overall.
More importantly: Does your eventUrl end in a "/"? I assume your DELETE endpoint is of the form https://somedomain.com/some/path/<id>, right? Now if eventUrl just contains https://somedomain.com/some/path your code constructs https://somedomain.com/some/path<id>. The last dash is missing, which definitely throws your backend off (how I cannot say, as that depends how the path is resolved in your server app).
It's hard to say what else is going from from the iOS app, but other than this potential pitfall I'd really recommend using proper Swift types where possible. Here's a cleaned up version of your method, hopefully that helps you a bit when debugging:
func deleteEvent(id: Int) {
guard let baseUrl = URL(string: eventUrl), let token = token else {
// add more error handling code here and/or put a breakpoint here to inspect
print("Could not create proper eventUrl or token is nil!")
return
}
let deletionUrl = baseUrl.appendingPathComponent("\(id)")
print("Deletion URL with appended id: \(deletionUrl.absoluteString)")
var request = URLRequest(url: deletionUrl)
request.httpMethod = "DELETE"
print(token) // ensure this is correct
request.allHTTPHeaderFields = ["Authorization": "Token \(token)"]
let task = URLSession.shared.dataTask(with: request) { data, response, error in
if let error = error {
print("Encountered network error: \(error)")
return
}
if let httpResponse = response as? HTTPURLResponse {
// this is basically also debugging code
print("Endpoint responded with status: \(httpResponse.statusCode)")
print(" with headers:\n\(httpResponse.allHeaderFields)")
}
// Debug output of the data:
if let data = data {
let payloadAsSimpleString = String(data: data, encoding: .utf8) ?? "(can't parse payload)"
print("Response contains payload\n\(payloadAsSimpleString)")
}
}
task.resume()
}
This is obviously still limited in terms of error handling, etc., but a little more swifty and contains more console output that will hopefully be helpful.
The last important thing is that you have to ensure iOS does not simply block your request due to Apple Transport Security: Make sure your plist has the expected entries if needed (see also here for a quick intro).
I'm struggling with getting this to work to make request to my API. Without a token works, but when I try to add additional headers, things turn to be complicated, for me.
First, the structure.
one class called: APIAsyncTask that makes the requests
one class called APIParams, just a data holder to send parameters to the APIAsyncTask class.
one class called DatabaseAPI that makes that builds the parameters, and send that to the APIAsyncTask class.
DatabaseAPI
func someMethod()
{
let task = APIAsyncTasks()
task.registerCallback { (error, result) -> Void in
print("Finished task, back at DatabaseAPI")
}
let params2 = APIParams(request: .GET, apiPath: "Posts/1", apiToken: "4iTX-56w")
task.APIrequest(params2)
}
APIAsyncTask
This part is for fixing another error, because manager was not global, the task got cancelled quickly.
var manager : Manager!
init(authenticatedRequest : Bool, token: String?)
{
manager = Alamofire.Manager()
print("Pre \(manager.session.configuration.HTTPAdditionalHeaders?.count)")
if(authenticatedRequest && token != nil)
{
var defaultHeaders = Alamofire.Manager.sharedInstance.session.configuration.HTTPAdditionalHeaders!
defaultHeaders["Authorization"] = "bearer \(token)"
let configuration = Manager.sharedInstance.session.configuration
configuration.HTTPAdditionalHeaders = defaultHeaders
manager = Alamofire.Manager(configuration: configuration)
}
print("Post \(manager.session.configuration.HTTPAdditionalHeaders?.count)")
}
After some decision making, it comes down to this part.
private func GetRequest(url: String!,token : String?, completionHandler: (JSON?, NSURLRequest?, NSHTTPURLResponse?, NSError?) -> () ) -> ()
{
print("Begin Get Request")
if(token != nil)//if token is not nil, make authenticated request
{
print("just before request: \(manager.session.configuration.HTTPAdditionalHeaders?.count)")
manager.request(.GET, url, parameters: nil, encoding: .JSON).responseJSON { (request, response, json, error) in
print("Get Request (authenticated), inside alamofire request")
var resultJson : JSON?
if(json != nil)
{
resultJson = JSON(json!)
}
completionHandler(resultJson, request, response, error)
}
}
else
{
//working part without token
So as the code is now, I get an error on completing:
Mattt himself gives the answer of using Alamofire.Manager.sharedInstance.session.configuration.HTTPAdditionalHeaders
, so that should be fine...
I suspect it has something to do with the multiple threads, according to this blog. Or, since it is something about CFNetwork, it could be because my API does not use SSL? I disabled NSAppTransportSecurity
I'm kind of new to swift, so examples would be really appreciated! Thankyou!
So the majority of your code looks solid.
The error leads me to believe that CFNetwork is having difficulty figuring out how to compute the protection space for the challenge. I would also assume you are getting a basic auth challenge since you are attaching an Authorization header.
Digging through your logic a bit more with this in mind led me to see that your not attaching your token to the string properly inside the Authorization header. You need to do the following instead.
defaultHeaders["Authorization"] = "bearer \(token!)"
Otherwise your Authorization header value is going to include Optional(value) instead of just value.
That's the only issue I can see at the moment. If you could give that a try and comment back that would be great. I'll update my answer accordingly if that doesn't actually solve your problem.
Best of luck!
You can add your headers in your request with Alamofire 2 and Swift 2.
For an example: go to example
I've created a script/api which is suppose to add a record to my database when running a specific url. However i'm not sure how to run this url. I do not expect anything back just to run this url? how can i do this?
var identifier = UIDevice.currentDevice().identifierForVendor.UUIDString
var addViewUrl = "http://url/addview.php?type=ios&identifier=\(identifier)&newsid=\(newsObject?.id)"
Based on my comment:
You should get a response and check for errors.
Also there is always the possibility to call a URL asynchronously to avoid blocking the GUI if the request takes a long time.
This can be made using delegate patterns or with completions handlers like in Objective-C.
Example:
var url = NSURL.URLWithString(addViewUrl)// Creating URL
var request = NSURLRequest(URL: url)// Creating Http Request
var queue: NSOperationQueue = NSOperationQueue()
NSURLConnection.sendAsynchronousRequest(request, queue: queue, completionHandler:{(response:NSURLResponse!, responseData:NSData!, error: NSError!) -> Void in
if error != nil
{
println(error.description)
}
else
{
var responseStr:NSString = NSString(data:responseData, encoding:NSUTF8StringEncoding)
//Everything went fine
}
})
I have the HTTP code in an AngularJS controller:
$http.post('/api/users/authenticate', {email: $scope.email, password: $scope.password})
.success(function (data, status, headers, config) {
authService.login($scope.email);
$state.go('home');
})
.error(function (data, status, headers, config) {
$scope.errorMessages = data;
$scope.password = "";
});
In the success case, the server will respond with a JSON representation of a user. In the error case the server will respond with a simple string such as User not found which can be accessed through the data parameter.
I'm having trouble figuring out how to do something similar in Alamofire. Here's what I have right now:
#IBAction func LoginPressed(sender: AnyObject) {
let params: Dictionary<String,AnyObject> = ["email": emailField.text, "password": passwordField.text]
Alamofire.request(.POST, "http://localhost:3000/api/users/authenticate", parameters: params)
.responseJSON {(request, response, data, error) in
if error == nil {
dispatch_async(dispatch_get_main_queue(), {
let welcome = self.storyboard?.instantiateViewControllerWithIdentifier("login") as UINavigationController;
self.presentViewController(welcome, animated: true, completion: nil);
})
}
else{
dispatch_async(dispatch_get_main_queue(), {
// I want to set the error label to the simple message which I know the server will return
self.errorLabel.text = "something went wrong"
});
}
}
}
I have no idea if I'm handling the non-error case correctly either and would appreciate input on that as well.
You are are on the right track, but you are going to run into some crucial issues with your current implementation. There are some low level Alamofire things that are going to trip you up that I want to help you out with. Here's an alternative version of your code sample that will be much more effective.
#IBAction func loginPressed(sender: AnyObject) {
let params: [String: AnyObject] = ["email": emailField.text, "password": passwordField.text]
let request = Alamofire.request(.POST, "http://localhost:3000/api/users/authenticate", parameters: params)
request.validate()
request.response { [weak self] request, response, data, error in
if let strongSelf = self {
let data = data as? NSData
if data == nil {
println("Why didn't I get any data back?")
strongSelf.errorLabel.text = "something went wrong"
return
} else if let error = error {
let resultText = NSString(data: data!, encoding: NSUTF8StringEncoding)
println(resultText)
strongSelf.errorLabel.text = "something went wrong"
return
}
var serializationError: NSError?
if let json: AnyObject = NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments, error: &serializationError) {
println("JSON: \(json)")
let welcome = self.storyboard?.instantiateViewControllerWithIdentifier("login") as UINavigationController
self.presentViewController(welcome, animated: true, completion: nil)
} else {
println("Failed to serialize json: \(serializationError)")
}
}
}
}
Validation
First off, the validate function on the request will validate the following:
HTTPStatusCode - Has to be 200...299
Content-Type - This header in the response must match the Accept header in the original request
You can find more information about the validation in Alamofire in the README.
Weakify / Strongify
Make sure to weak self and strong self your closure to make sure you don't end up creating a retain cycle.
Dispatch to Main Queue
Your dispatch calls back to the main queue are not necessary. Alamofire guarantees that your completion handler in the response and responseJSON serializers is called on the main queue already. You can actually provide your own dispatch queue to run the serializers on if you wish, but neither your solution or mine are currently doing so making the dispatch calls to the main queue completely unnecessary.
Response Serializer
In your particular case, you don't actually want to use the responseJSON serializer. If you do, you won't end up getting any data back if you don't pass validation. The reason is that the response from the JSON serialization is what will be returned as the AnyObject. If serialization fails, the AnyObject will be nil and you won't be able to read out the data.
Instead, use the response serializer and try to parse the data manually with NSJSONSerialization. If that fails, then you can rely on the good ole NSString(data:encoding:) method to print out the data.
Hopefully this helps shed some light on some fairly complicated ways to get tripped up.
So Alamofire treats all requests successful. This really comes down to the API server http headers being returned.
You could use Alamofire.Request.validate()
It'll allow you to validate http headers, etc. Check out the example
https://github.com/Alamofire/Alamofire#validation
I am assuming the the error message will be in the data object.
to access the values from data you could do something like
I am not really sure about your api response looks but in this example
{
"message": "Could not authenticate"
}
let message: String? = data?.valueForKey("message") as String