track view duration and upload as a Localytics event attribute for charting

XYZViewController.m

#import "XYZViewController.h"
#import "LocalyticsSession.h"
 
@interface XYZViewController ()
 
@end
 
@implementation XYZViewController

static NSDate *startOfOverallTime;
 
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}
 
- (void)viewDidLoad
{
    [super viewDidLoad];
    
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    
    //Localytics screen tag
    [[LocalyticsSession shared] tagScreen:@"XYZ screen"];
    
    //start duration
    startOfOverallTime = [[NSDate date] retain];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:(BOOL)animated];    
    
    //duration calculation
    NSString *duration;
    NSDate *endOfOverallTime = [NSDate date];
    NSTimeInterval overallTimeTaken = [endOfOverallTime timeIntervalSinceDate:startOfOverallTime];

    [startOfOverallTime release];

    //add duration to attributes dictionary
    NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys: 
      overallTimeTaken,
      @"Duration",      
      nil];

    //upload as attribute to Localytics
    [[LocalyticsSession shared] tagEvent:@"XYZ Screen Summary" attributes:dictionary]; 
    
}


@end