I want to start a wait animation/show UIAlertView before calling a segue so that the user will know they have to wait for a couple of seconds while the segue gets processed and the next ViewController gets populated with relevant data and shows up!
The problem is performSegueWithIdentifier prevents any kind of animation/UIAlertView to show up. Only after the segue finishes then the animations get their chance to popup!
How to solve this ?
You should be able to implement your animation logic in the prepareForSegue method. That method gets called and finished before the segue is executed.
Also, if this flow doesn't fit, fire off the performSegue method when the animation is over or the user responds to the UIAlertView that you have fired off.
OR if you haven't been using MBProgressHUD, take a look at that. I use this when I am dealing with external data and want the user to know something is going on (getting data from a web-service). It is easy and simple to implement.
Related
RESOLVED
I was performing the segue from inside a block and it was another thread. When I specifically move the operation back to the main thread it works great.
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
[self performSegueWithIdentifier:#"LoadToDisplay" sender:self];
}];
QUESTION
I want to programmatically present a view controller.
My app downloads some data from the internet, carries out some data handling and then loads the next view.
I use performSegueWithIdentifer successfully throughout the rest of the app however for some reason it is adding a huge delay with this specific transition.
I've used presentViewController with no delay but I can't use this, it was just to test whether I was missing something obvious.
I have an NSLog when the last data handling method completes and one when the next view controller is loaded. Using 'presentViewController' the time between logs is 14ms. When using performSegueWithIdentifer is a staggering 8.5secs!
I literally commented out one line and tested with the other. No other code changes.
Has anyone else experienced this or know what might be going on?
Thanks.
in a ViewController, that hosts a TableView, I load the data for the table view using AFNetworking in viewDidLoad.
This can take a couple of seconds. If during the network call, the users swipes back to the previous VC, the app crashes. I think it is because the network call is still running, comes back and the original callback for the network call is somehow lost?
I started using stuff like "userInteractionEnabled = false" and setting it back to true when the data finished loading or setting a global variable in viewWillDisappear and checking this in the callback. This works but seems quite wrong.
What is the proper method/func to load data for a table view?
How is a situation like this properly handled, e.g. should I cancel all AFNetworking request in viewWillDisappear?
Thanks a lot for a hint!
This is how my application is looking now:
After I perform a database update in my detail controller in view number 7 in the image above as soon as the save button is clicked the details are saved the the database. I'm taken back to tableView number 5 and expect the associated row to show latest updates by calling a special method from the parse.com framework that reloads objects and refreshes the table view e.g. [self loadObjects].
I use an unwind segue. In view 7 I make a connection between the save button and the exit symbol of it's controller window in interface builder and then in tableView number 5 I have my segue method that corresponds to this connect.
Unwind segue method:
-(IBAction)saveDetailsButtonTapped:(UIStoryboardSegue *)segue {
// alert goes here
[self performSelector:#selector(didTapRefreshButton:) withObject:self afterDelay:1.0];
}
This method clears the table and loads the first page of objects:
- (IBAction)didTapRefreshButton:(id)sender {
[self loadObjects];
}
When save is clicked on view number 7 the details are saved to the db and user is bought back to table view number 5 then the method above runs after 1.0 delay. I thought this was ok but didn't feel too right. I tried it on my phone and sometimes the delay wasn't long enough, meaning a failed refresh.
I then decided to try using a UIAlertView delegate method to detect when the ok button of the alertview was pressed and it worked ok most times but then the times I pressed OK to dismiss the alert really quickly upon arriving back on the view and the data wasn't reloaded.
Is there a better solid reliable way to refresh my data?
I need some way of knowing that the database update was successful and only then run the [self loadObjects] method and maybe do that automatically.
I have two methods that detect when objects will load (e.g. like when a button has been tapped) and when they have loaded. I have put some spinner code in there to show a spinner while loading is happening and take it away once it's done.
Isn't there some sort of way to queue methods, like some how in one method make it so one thing doesn't happen until another thing has happened?
If so, I'd really appreciate some insight and examples as I could just mark the app as complete but even though I'm not being paid and it's charity work I still have the urge to do my best.
Thanks for your time.
Kind regards
I have put some spinner code in there to show a spinner while loading is happening and take it away once it's done.
You should do something like that here.
I need some way of knowing that the database update was successful and only then run the [self loadObjects] method and maybe do that automatically.
Because you're saving to parse, it should be the parse SDK that tells you when the save is complete. If you're saving in the background (which you should be) then use the save method when provides you with a callback block that is called when the save has completed. This block being called is your trigger to remove the spinner and segue.
Side note :-
Yes, there are several different kinds of queues, most better than using performSelector:..., but there are also other ways of working with asynchronous activities and you should look at the asynchronous activity for guidance. i.e. can I get a callback when this is done, rather than how long should I wait and hope that it is done.
I have a UITableView that requests for more data from the server when the user hits the bottom of the table (similar to the Twitter application). However, I'm trying to use a modal segue to filter out data to the user's desire. In order to properly select which data to filter, I have to load ALL of the data to categorize it. In order to load everything, I am required to send out multiple NSURLConnections to load multiple pages. I am trying to have it so when one completes, the next one starts.
However since the connection completes with connectionDidFinishLoading, I have not figured out a way to send out simultaneous NSURLConnections from within prepareForSegue. I tried using a while loop in prepareForSegue as follows:
while (All of the data is not loaded) {
if (isLoading == NO) {
[self loadMoreResults];
}
}
where "isLoading" is a BOOL declared in my viewcontroller's implementation file. isLoading changes value to YES inside loadMoreResults, and changes back to NO at the end of connectionDidFinishLoading. However, within prepareForSegue, isLoading never changes back from YES to NO.
Is this a multithreading issue? I have done research on other questions and see that NSURLConnection has a class method sendAsynchronousRequest:queue:completionHandler: where the completion handler might help, but I'm unsure how I would use it.
ALSO: I want to continue executing prepareForSegue AFTER the last connection finishes, not right after it sends the request.
Thanks in advance!
Then you should not link the segue directly from the bar button item to the view controller in the storyboard.
Just link a general segue with identifier from the table view controller to the filter view controller.
And from the bar button item, create an action for it from the storyboard so that you can send out multiple NSURLConnections first.
Finally then in your code, after the last connection finishes, call the performSegueWithIdentifier method.
I'm using MBProgressBar in my app to display feedback whenever there is a call to a certain webService.
To do so, in the method "requestStarted" of ASIHTTPRequest, I call:
[NSThread detachNewThreadSelector:#selector(startLoader) toTarget:self];
Where startLoader is the method that pops the HUD.
Now, the thing is that whenever I call startLoader directly, the HUD gets displayed with no problem, but when I call the method using the detachNewThreadSelector thing (which is needed), the HUD is displayed but with no text label.
If I had to guess, I would say I need to force-refresh the component, but I don't know how to do that.
Anything having to do with the HUD will need to be done on the main/UI thread. If you are detach and put on a background thread, the HUD will likely never get those updates because your request will finish before getting back around to the main thread.