Put a boolean False inside a runloop while

Question

i'm trying to get directory file listing from my ftp server using Chilkat library. In this case, i want to animating a UIActivityIndicatorView when the process is running. But the problem is, the UIActivityIndicatorView never start to animate. The code I use is :

[self.activityIndicator startAnimating];
[selfgetListFromPath:ftpPath withConnection:ftpConnect];
[self.activityIndicator stopAnimating];

activityIndicator is an object of UIActivityIndicatorView, ftpPath is a NSString of my file path in FTP server, and getListFromPath is the method for getting list from FTP server using Chilkat algorithm, ftpConnect is an object of FTP Connection Class.

I was try to use NSRunLoop before called getListFromPath function, so I changed my code into :

[self.activityIndicator startAnimating];

BOOL waitingOnProcessing = YES;
NSRunLoop *currentRunLoop = [NSRunLoop currentRunLoop];
while (waitingOnProcessing && [currentRunLoop runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]) {

}

[self getListFromPath:ftpPath withConnection:ftpConnect];
[self.activityIndicator stopAnimating];

this make the activityIndicator animating, but the getListFromPath never fired. After a trial, i choosed to changed again my code into :

[self.activityIndicator startAnimating];

    BOOL waitingOnProcessing = YES;
    NSRunLoop *currentRunLoop = [NSRunLoop currentRunLoop];
    while (waitingOnProcessing && [currentRunLoop runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]) {
        waitingOnProcessing = NO;       
    }

    [self getListFromPath:ftpPath withConnection:ftpConnect];
    [self.activityIndicator stopAnimating];

it make the activityIndicator animating, and also fired the getListFromPath function. But i'm doubt with this code, am i right with this code? or maybe there is a bad practice for using NSRunLoop? can somebody tell me

Thank you

Finally, i have found the answer, this http://www.icodeblog.com/2010/03/04/iphone-coding-turbo-charging-your-apps-with-nsoperation/ link help me to find the solution — R. Dewi, Aug 02 '11 at 05:17

score 0 · Answer 1 · answered Jul 12 '11 at 09:38

0

I dont know the Chilkat library, but it must have some way of telling you that you receive an answer from your ftp server. When you got it, you should use a NSNotification or a protocol to tell your view controller that you got an answer. When that happen you stop the spinner.

answered Jul 12 '11 at 09:38

Rui Peres

25,741
9
87
137

I just have the answer from my FTP server, and i have all the list that i want to get, but the problem is, i can't start my activityIndicator to animating. But my last code, make me can do it. The problem is, i just doubt with that code, can i just do that? – R. Dewi Jul 12 '11 at 09:41
I don't think your last bit of code is the right way of doing it. You need to be sure that you got the answer, only need you stop the the spinner – Rui Peres Jul 12 '11 at 09:50
using the last code i've made, the spinner is stop after the file listing is showed. Can you tell me another way to do it? – R. Dewi Jul 12 '11 at 09:52
Tell me one thing, does the Chilkat library provide you some sort of a gotResponseFromServer method? – Rui Peres Jul 12 '11 at 09:54
Hmm, i think there is a logic like that in Chilkat library – R. Dewi Jul 12 '11 at 09:57
If there is, you can put a NSNotification inside. Or create a protocol, so the Chilkat library can communicate with your view controller. – Rui Peres Jul 12 '11 at 09:59
@JackyBoy let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/1356/discussion-between-risma-and-jacky-boy) – R. Dewi Jul 12 '11 at 10:01

score 0 · Accepted Answer · answered Jul 12 '11 at 09:42

0

This code runs as in a "black box" :

[self.activityIndicator startAnimating];
[self getListFromPath:ftpPath];
[self.activityIndicator stopAnimating];

So UI updates occur when your method returns, and you won't see the update.

What you need to do is startAnimating your activity indicator, then start your getListFromPath in another thread. When that method terminates, you call back your main thread telling it to stopAnimating the indicator.

Use this methods:

[NSObject performSelectorInBackground:withObject:]

to start your getListFromPath thread, then when it's done, call

[NSObject performSelectorOnMainThread:withObject:waitUntilDone:]

to give the control back to the main thread, which will stop the spinner animation.

answered Jul 12 '11 at 09:42

Cyrille

25,014
12
67
90

Forgot to tell you: just remember to *always* do UI updates on the main thread. – Cyrille Jul 12 '11 at 09:43
Thank you for your answer, but if i use a performSelectorInBackground:withObject:, it make me have to use @selector(getListFromPath:), right? How about the ftpPath parameter? i cant get the directory file listing without that parameter, can you give me another clue? – R. Dewi Jul 12 '11 at 09:47
You have to create a `threadedGetListFromPath` method, that will setup an autorelease pool, and start the getListFromPath from inside. Then, call `[self performSelectorInBackground:@selector(threadedGetListFromPath)]` from your main thread. The `ftpPath` will still be accessible from this method as long as it's a private member (variabe) of the same class. Beware not to modify it as you may run into concurrency problems. – Cyrille Jul 12 '11 at 09:50
Maybe take a look at this introduction: http://www.chrisumbel.com/article/asynchronous_iphone_nsthread_nstimer – Cyrille Jul 12 '11 at 09:51
hmmm...i'm not get it, can you give me an example of threadedGetListFromPath method? – R. Dewi Jul 12 '11 at 09:53
Take a look at this similar question : http://stackoverflow.com/questions/441345/does-uiactivityindicator-require-manual-threading-on-iphone – Cyrille Jul 12 '11 at 09:55
i have a problem with that link, if i have 2 parameter for running my function, what i have to do? please see my update for the getListFromPath method – R. Dewi Jul 12 '11 at 10:11
@Cyrille let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/1358/discussion-between-risma-and-cyrille) – R. Dewi Jul 12 '11 at 10:13
No matter how many parameters you have, as your method is called from threadedGetListFromPath (which takes *no* parameter). All you have to do is make them accessible from anywhere in your class, by declaring them @private in your header file. – Cyrille Jul 12 '11 at 10:13

Put a boolean False inside a runloop while

2 Answers2