NetworkActivityStatus.h

@interface NetworkActivityStatus : NSObject

+ (instancetype)sharedStatus;
- (void)pushNetworkActivity;
- (void)popNetworkActivity;

@end

NetworkActivityStatus.m

#import "NetworkActivityStatus.h"

@interface NetworkActivityStatus ()

@property (nonatomic) dispatch_queue_t networkActivityCounterQueue;
@property (nonatomic) NSUInteger networkActivityCounter;

@end

@implementation NetworkActivityStatus

+ (instancetype)sharedStatus
{
    static NetworkActivityStatus *status;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        status = [self new];
    });

    return status;
}

- (id)init
{
    self = [super init];
    if (!self) return nil;

    self.networkActivityCounterQueue = dispatch_queue_create("NetworkActivityStatus Queue", NULL);

    return self;
}

#pragma mark - Public Methods

- (void)pushNetworkActivity
{
    dispatch_sync(self.networkActivityCounterQueue, ^{
        self.networkActivityCounter++;
        [self updateNetworkActivityIndicator];
    });
}

- (void)popNetworkActivity
{
    dispatch_sync(self.networkActivityCounterQueue, ^{
        self.networkActivityCounter--;
        [self updateNetworkActivityIndicator];
    });
}

#pragma mark - Private Methods

- (void)updateNetworkActivityIndicator
{
    [[NSOperationQueue mainQueue] addOperationWithBlock:^{
        if (self.networkActivityCounter == 0) {
            [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        } else {
            [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
        }
    }];
}

@end