MBProgressHUD showAnimated: whileExecutingBlock: not working - ios

Question

I'm using a method for scanning Bluetooth device, which I import from another framework. The scanning method would take a while, and it'll block the GUI, which is what we never want to happen.
I'm also having MBProgressHud, trying to show a hud while scanning, but it's not working (hud not showing up). Any help?
Here's the code I'm currently using:
[hud showAnimated:YES whileExecutingBlock:^{
self.btDevices = [Util scanBT];
}];
Edit 1: Okay, so if I use this code, it'll still block my UI for a while, then all suddenly continue to run.
hud = [[MBProgressHUD alloc] initWithView:self.view];
hud.labelText = #"Now scanning";
hud.dimBackground = YES;
hud.opacity = 0.5;
[hud show:YES];
[hud hide:YES afterDelay:5.0];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.001 * NSEC_PER_SEC), dispatch_get_main_queue(), ^(void){
self.btDevices = [Util scanBT];
});
Edit 2: Ok, I will post all my block of code:
hud = [[MBProgressHUD alloc] initWithView:[self getTopView:self.view]];
hud.labelText = #"Now scanning";
hud.dimBackground = YES;
hud.opacity = 0.5;
[hud showAnimated:YES whileExecutingBlock:^{
self.btDevices = [Util scanBT];
}];
dispatch_queue_t myqueue = dispatch_queue_create("queue", NULL);
dispatch_async(myqueue, ^{
//Whatever is happening in the BT scanning method will now happen in the background
dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUDForView:[self getTopView:self.view] animated:YES];
});
});
/** Recursion to get the top most view in view layer. */
- (UIView *)getTopView:(UIView *)view
{
if ([view.superview class]) {
return [self getTopView:view.superview];
}
return view;
}
I'm request scanning bt in a popover, but I want to show HUD in a main View, so I write a block to retrieve the main view. Maybe that's where the problem occur?

Answer 1

Try this:
In your viewDidload or the method where you want to place it
MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
[hud setDimBackground:YES];
[hud setOpacity:0.5f];
[hud show:YES];
[hud hide:YES afterDelay:5.0];
[self performSelector:#selector(startScanning) withObject:nil afterDelay:5.0];
And your method
- (void) startScanning {
self.btDevices = [Util scanBT];
}
OR I think you should try it running
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.001 * NSEC_PER_SEC), dispatch_get_main_queue(), ^(void){
// Insert task code here
self.btDevices = [Util scanBT];
});
Try it with completion block
[hud showAnimated:YES whileExecutingBlock:^{
self.btDevices = [Util scanBT];
} completionBlock:^{
//code for after completion
}];
OR you can also try this
[MBProgressHUD showHUDAddedTo:self.view animated:YES];
dispatch_queue_t myqueue = dispatch_queue_create("queue", NULL);
dispatch_async(myqueue, ^{
//Whatever is happening in the BT scanning method will now happen in the background
self.btDevices = [Util scanBT];
dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
});