completionhandler

问题 I have read up a lot on this subject but have still been stumped on this specific problem. I have many Firebase calls that rely on each other. This is a kind of simplified example of my code. I had trouble making it any shorter and still getting the point across: class ScoreUpdater { static let ref = Database.database().reference() var userAranking = Int? var userBranking = Int? var rankingAreceived = false var rankingBreceived = false var sum = 0 // Pass in the current user and the current

问题 here is the thing, I wants to save the today steps into Core Data in completionHandler. But while I load this value,the complier shows it a nil. any solution? func fetchDataOfQuantityType(startDate: NSDate, endDate: NSDate, quantityType: HKQuantityType, completion:((NSArray, NSError!) -> Void)!) { // initial a predicate with startDate and endDate let predicate = HKQuery.predicateForSamplesWithStartDate(startDate, endDate: endDate, options: HKQueryOptions.StrictStartDate) // initialize a

问题 Having just learned about how to create completion handlers, I understand them in principle, but I don't know how to put the ideas into practice to accomplish what I need. I have the following general code and storyboard structure: sessionVC (a UIViewController) and its UIView hold a container view with an embed segue to animationVC (also a UIViewController) and its SKView. From sessionVC I want to run a series of animations in animationVC’s SKView. I’d like to prepare each animation as soon

问题 I am trying to use a completion handler in a for loop. The problem is that it will keep running the loop before the completion handler returns since it is an async call. Attached is my code. Do I need to use GCD? I am new (obviously)to swift/ios. Any advice would be much appreciated. Bob for srcTerm in sFields { //search using all search fields multiQuery (searchTerm: srcTerm) { if srResult.count < self.lastValue { self.lastValue = srResult.count self.lastSearch = srcTerm } } // Do more stuff

问题 I am attempting to open an app in one of two ways: If the user has no UserDefaults saved, then open up a WelcomeViewController If the user has UserDefaults saved, then open up a MenuContainerViewController as a home page In step 2, if there are UserDefaults saved, then I need to log a user in using Firebase which I have through a function with a completion handler. If step 2 is the case, I want to open MenuContainerViewController within the completion block without any UI hiccups. Here is the

问题 I am developing a networkUtil for my project, I need a method that gets a url and returns the JSON received from that url using NSURLSessionDataTask to get a JSON from server. the method is the following: + (NSDictionary*) getJsonDataFromURL:(NSString *)urlString{ __block NSDictionary* jsonResponse; NSURLSession *session = [NSURLSession sharedSession]; NSURLSessionDataTask *dataTask = [session dataTaskWithURL:[NSURL URLWithString:urlString] completionHandler:^(NSData *data, NSURLResponse

问题 I have a function performSync which runs through an array and for each item in this array, I am calling a function which in itself contains an async alamofire request. I need to be able to tell when this outer function has completed running all functions within the for loop, so I need to add a completion handler. I am unsure how to implement this. Also, in my for loop, I have used .userinitiated in order to try and not block the ui thread, however the thread is being blocked. I also tried

问题 I'm trying to figure out how to tell when the animation is finished for the following: self.mapView.setRegion(MKCoordinateRegionForMapRect(mapRect), animated: true) It doesn't look like setRegion supports a completion handler like other commands. I know how to create a generic completion handler using something like this: How could I create a function with a completion handler in Swift? But I don't know what variable to check to verify the animation has completed. 回答1: You can implement the

问题 The Javadoc for AsynchronousByteChannel.read() says the operation takes place asynchronously, but what happens when the end of stream has been reached? Is an implementation allowed to fire the completion handler within the same thread that invoked read()? From the implementation's point of view, there is no reason to carry out this operation asynchronously, because we already know the result. Similarly, if a user attempts to read into a ByteBuffer where remaining() returns 0 we know the read

问题 I have a method which handles a Apple Push Notification Service remote notification. When this method is executed, I want it to call my server and do a HTTP POST request using the Alamofire library. I want to execute another method that will handle the response of the POST request. The problem for me is that I am using an existing API to fetch a profile from the server in this POST request. So I need to use this existing API and figure out when this profile fetch is specifically triggered