I have a UITableView which loads its data from the web. It takes a while to load this data and therefore I would like an acitivity indicator to animate while the data is loading. I am doing the following in my attempt to make this work:
1) In viewDidLoad I add an observer to listen to when the data loading is done and after that I call loadDataFromWeb
2) loadDataFromWeb creates the activity indicator, adds it as a subview to self.view and then it loads the data. At last it posts a notification (the one that viewDidLoad observes) to indicate that the loading process is done.
3) Finally, when the observer catches the post from loadDataFromWeb, it calls removeLoadingScreen to remove the indicator.
Pretty obvious I am not seeing my indicator view. If I comment out the line that removes the indicator, it stays on the screen when everything is loaded. I am aware that I'm probably messing around with which methods are called when in the process, and this is where I need help.
I should mention that the whole purpose is that instead of the user's looking at a screen on which nothing is happening (while the data loads), I want a activity indicator to show up to indicate that there's something going on here.
Thanks
#Muncken have a look at this MBProgresHUD project, this will help you a lot to do a downloading progress in background (secondary thread not main thread) and shows a activity indicator over you view -
https://github.com/matej/MBProgressHUD
Related
I'm doing an app that uses a TabBarController and each Tab uses its own navigation controller.
The app has dynamic content and I use viewDidDisappear viewDidAppear methods to create or destroy the objects that I need each time I enter or exit into the ViewController.
My problem is when I start to sail very fast and I don't give time to load the Threads that I use for uploading content such as XML peta app or destroy objects when I leave the ViewController.
How I could control the tabs of the navigationbar or tabbarviewcontroller for not respond until the viewcontroller has loaded all contents?
Excuse me if I'm not well expressed. Thanks!
No matter you use synchronous request or asynchronous request, just show an UIAlertView while loading the data. This will both serve as a notification to the user that something is being loaded, and the it will block the interactions with all the other views on the screen.
As others have suggested in comments, I believe that what you want to do is rearrange the order in which things are triggered. Perhaps something like this:
On viewWillAppear:, clear (or disable or whatever is appropriate) your objects that are no longer valid and begin the load-new-content thread. Perhaps display a UIActivityIndicator or similar.
On viewWillDisappear:, tell the load-new-content thread that it can stop, its results are no longer needed. If you put up an activity indicator, take it down.
At the end of the load-new-content thread, take down any activity indicator, update the UI with the new contents and activate.
I don't really see any way around this -- if the UI is not valid until the new content is loaded, then you have to wait for it.
Another solution might be to cache the contents from the previous fetch, and always display those on viewDidLoad. Then, at the end of your new-content-thread, cache the new contents, and update the UI.
I've made a custom activity indicator (actually just an imageView)
When user clicks something and I expect it will take a bit long to process(alloc a UIViewController and push on to navigation stack),
I alloc the indicator and add it as subview of current view just before the lengthy process starts.
Strange thing is, indicator doesn't show up until the push (left-right) animation starts.
Is it because the lengthy job takes the system, and ui drawing for activity indicator is delayed?
Am I doing something wrong here?
Thank you
Edit
Looks like I can do the "push" in background.. i'm trying it now
IPhone SDK - Leaking Memory with performSelectorInBackground
Is your job synchrone or asynchrone ?
If it's the first case, then it can be the problem.
Check all the method like :
[ self performSelector:<#(SEL)aSelector#> ];
You can thread this to avoid your [potential] problem.
Good luck.
You should process your lengthy tasks in the background. The UI won't update if you block the main thread.
So you have to refactor your app, the alloc and push of the viewController should happen within the blink of an eye, because you can't do this in the background.
But you can do the processing (downloading data I guess) in the background.
There is plenty information available about background processing. The way to go varies heavily on what you want to do exactly.
I allow the user to manage records on other views. I set a flag if certain changes are made.
Then on the flag (where the data changes will have an impact) I run some methods / queries which create the data which is used in my table view(s). This workload currently happens in viewWillAppear(s).
This could take a few seconds and I'd like to show my progress indicator view which I wrote today, it uses a transparent view with a activity indicator in the center of the view.
[self performSelectorInBackground:#selector(startupStuff) withObject:sender];
However, viewWillAppear won't wait while I run the the work in the background.
Ideally I'm looking for a quick fix to work around this problem.
Any ideas ?
However, viewWillAppear won't wait while I run the the work in the background.
That's the whole point of it, isn't it? At the end of your startupStuff method, you should call another method on the main thread (with performSelectorOnMainThread:...) that is used to (a) inform the controller that your data is ready, (b) reload the table view and (c) dismiss your progress indicator view.
I have a subview where there is an uitableview that gets data from an online server (title, subtitle and image). When I click the button that shows the subview it takes a little time to get there using WiFi connection, but under 3G network it takes longer, so that you really feel the gap between loading the view and having pressed the button
what I'd like to do, is to display an uiactivityindicatorview when you press the button and after loading the view, and when it has loaded stop the activity indicator
how can I check that the uitableview has finished loading ?
do you have other suggestions ?
Thanks in advance
Use asynchronious requests or threading (take a look at NSOperation)
Look into doing network operations asynchronously, rather than blocking the main UI's thread. ASIHTTPRequest is a really good library for this: http://allseeing-i.com/ASIHTTPRequest/
As the others said, if you are not using an asynchronous approach to this, I strongly suggest you to do so, because otherwise you will block your application for as long as the data is being downloaded.
With that said, you could show the activity indicator while the data is being loaded, and that is until the delegate method
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
is called. Then, your table should be populated with the data and the indicator would dissapear.
I hope this helped you a bit
I am working on a an application which is very simple
a navigation controller with a table view
when the user clicks a row, he is directed to the details view.
However, the details view pulls data from Core Data. i am pulling a relatively large amount of data that takes about three seconds to load.
I wanted to add that UIActivityIndicatorView to show progress.
I tried to start the animation once the user clicks the row, so i set it to animate in didSelectRowAtIndexPath
For some reason, the Activity Indicator doesn't start before the pushing of the details view.
Any idea why? or the best way to implement such an idea?
~Adham
Because you start the animation and then start a large operation in the same thread. Consider running that 3 second operation in a new thread. Look at NSOperationQueue and then create a NSOperation to run that procedure. It will work this way.
The UI doesn't update until the end of your run loop. You are, in sequence, displaying the activity monitor, then pushing the new table view, and then the UI updates. You need to change this order.
You can either move something to a different thread, or you could perhaps delay the loading of the new table view by calling performSelector:afterDelay: with a delay of 0. That will delay the loading of the new table view until after the activity indicator appears in the UI. Now, it's still all on the same thread, so you will be blocked from doing anything, but if the animation is threaded in the activity monitor, it would make for a quick and easy solution.
Call method in thread:
[NSThread detachNewThreadSelector: #selector(loadMethod) toTarget:self withObject:nil];
See following for more details:
http://iphone.zcentric.com/?s=UIActivityIndicatorView