How to show the loading indicator in the top status bar

Question

I have noticed that some apps like Safari and Mail show a loading indicator in the status bar (the bar at the very top of the phone) when they are accessing the network. Is

Answer 1

I wrote a singleton that solves the problem of multiple connections by keeping a counter of what is happening (to avoid removing the status when a connection returns but another one is still active):

The header file:

#import 

@interface RMActivityIndicator : NSObject

-(void)increaseActivity;
-(void)decreaseActivity;
-(void)noActivity;

+(RMActivityIndicator *)sharedManager;

@end

and implementation:

#import "RMActivityIndicator.h"

@interface RMActivityIndicator ()

@property(nonatomic,assign) unsigned int activityCounter;

@end

@implementation RMActivityIndicator

- (id)init
{
    self = [super init];
    if (self) {
        self.activityCounter = 0;
    }
    return self;
}

    -(void)increaseActivity{
        @synchronized(self) {
             self.activityCounter++;
        }
        [self updateActivity];
    }
-(void)decreaseActivity{
    @synchronized(self) {
           if (self.activityCounter>0) self.activityCounter--;
    }
    [self updateActivity];
}
-(void)noActivity{
    self.activityCounter = 0;
    [self updateActivity];
}

-(void)updateActivity{
    UIApplication* app = [UIApplication sharedApplication];
    app.networkActivityIndicatorVisible = (self.activityCounter>0);
}

#pragma mark -
#pragma mark Singleton instance

+(RMActivityIndicator *)sharedManager {
    static dispatch_once_t pred;
    static RMActivityIndicator *shared = nil;

    dispatch_once(&pred, ^{
        shared = [[RMActivityIndicator alloc] init];
    });
    return shared;
}

@end

Example:

    [[RMActivityIndicator sharedManager]increaseActivity];
    [NSURLConnection sendAsynchronousRequest:urlRequest queue:self.networkReceiveProcessQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
    {
        [[RMActivityIndicator sharedManager]decreaseActivity];
    }