dispatch_after CLLocationManager didUpdateLocations or didFailWithError - ios

Question

I have this piece of code managing a "pull to refresh" which updates the location of the device:
[self.glassScrollView.foregroundScrollView addPullToRefreshWithActionHandler:^{
int64_t delayInSeconds = 1.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
NSLog(#"Pulled");
[weakSelf.locationManager startUpdatingLocation];
[weakForegroundScrollView.pullToRefreshView stopAnimating];
});
}];
When it STARTS updating the location the animation stops, but NOT when it actually updates the location or returns an error for it. This creates the awkward situation in which it appears to have updated the location and the UI (the spinning wheel animation disappeared), but it is still processing it through the CLLocationManagerDelegate methods.
So, what's the best way to "connect" the locationManager:didUpdateLocations and the locationManager:didFailWithError methods with this queue?
I was thinking about adding some sort of "listener" in the code above waiting for a certain method to be called inside the CLLocationManagerDelegate methods.
Here's also my locationManager:didUpdateLocations method.
(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
NSLog(#"didUpdateLocations");
CLLocation *currentLocation = [locations lastObject];
// do stuff in the UI
// I stop updating the location to save battery
[self.locationManager stopUpdatingLocation];
}
Thanks!

Answer 1

Ok. This code might help:-
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(whenCompleted) name:#"whenCompleted" object:nil];
}
-(void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self name:#"whenCompleted" object:nil];
}
-(void)whenCompleted{
[weakForegroundScrollView.pullToRefreshView stopAnimating];
}
When all the methods are executed, before the end of the last method, post the notification:-
[[NSNotificationCenter defaultCenter]postNotificationName:#"whenCompleted" object:nil];
Then it will stopAnimating when the progress is completed.

Answer 2

You handle the pull request with something like:
[self.glassScrollView.foregroundScrollView addPullToRefreshWithActionHandler:^{
int64_t delayInSeconds = 1.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
NSLog(#"Pulled");
[weakSelf.locationManager startUpdatingLocation];
[weakForegroundScrollView.pullToRefreshView stopAnimating];
});
}];
I'm assuming that one second delay is because you want to hide the pull to refresh after one second, even though the refresh is still in progress.
What I'd suggest is:
[self.glassScrollView.foregroundScrollView addPullToRefreshWithActionHandler:^{
[weakSelf.locationManager startUpdatingLocation];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.5 * NSEC_PER_SEC);, dispatch_get_main_queue(), ^(void){
[weakSelf.glassScrollView.foregroundScrollView setContentOffset:CGPointZero animated:YES];
});
}];
This keeps the UIActivityIndicatorView spinning, but scrolls it off screen. If you pull it down again, you'll see it's still going. That's an easy way to keep the activity indicator going, but getting it out of the user's way.
And then, as Ricky says, only when the location is retrieved would you stopAnimating (or post a local notification to the [NSNotificationCenter defaultCenter] so your observer can do that). But do not just try to stopAnimating after a set period of time, but rather tie that to the actual completion of whatever asynchronous task you were performing.