CODEWITHSUNDEEP
iosobjective-ccocoa-touchuiactivityindicatorview
seidju
seidju

Reputation: 113

ActivityIndicator doesn't stop after computations

I'm trying to make activity indicator while uploading files, so i've found a lot of solutions, but i guess i don't fully understand them, so my code look like this:

- (void) startSpinner {

UIActivityIndicatorView  *spinner = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
[spinner setCenter:CGPointMake(self.view.frame.size.width/2.0, self.view.frame.size.height/2.0)];
[self.view addSubview:spinner];
[spinner startAnimating];

}


- (void)startSync {

[NSThread detachNewThreadSelector:@selector(startSpinner) toTarget:self withObject:nil];

// computations 

[self.spinner stopAnimating];
}

So after i do [self startSync] activityIndicator appears, but after uploading it didn't stop. Also if i declare activity indicator somewhere else (not in the (void)startSpinner), for example in viewDidLoad, and only do [self startAnimating] it didn't appear at all. Please help me find out errors.

Upvotes: 2

Views: 1431

Answers (3)

RealityOD
RealityOD

Reputation: 69

It happens become you declare local variable spinner inside startSpinner method.

When you call self.spinner, it does not affect the local variable spinner you declared inside startSpinner method. You have 2 separate variable with same name.

You have to declare

spinner = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

Upvotes: 1

Stavash
Stavash

Reputation: 14304

You're performing UI operations on a thread that isn't the main thread. You should never call detachNewThreadSelector with a selector that performs UI related tasks.

A better, more understandable way to do this is:

dispatch_async(dispatch_get_main_queue(), ^{
    [self.activityIndicator startAnimating];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        //Perform lengthy operations
        dispatch_async(dispatch_get_main_queue(), ^{
            [self.activityIndicator stopAnimating];
        });
    });
});

Also, if you choose to work with selectors - make sure your UIActivityIndicatorView is declared outside the scope of the method.

Upvotes: 4

ZGl6YXNt
ZGl6YXNt

Reputation: 1814

- (void) startSpinner
{
    self.spinner = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
    [spinner setCenter:CGPointMake(self.view.frame.size.width/2.0, self.view.frame.size.height/2.0)];
    [self.view addSubview:spinner];
    [spinner startAnimating];
}


- (void)startSync
{
    [NSThread detachNewThreadSelector:@selector(startSpinner) toTarget:self withObject:nil];

    // computations 

    [self.spinner performSelectorOnMainThread:@selector(stopAnimating) withObject:nil waitUntilDone:NO];
    self.spinner = nil;
}

Upvotes: 1

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