Run timer in background thread

ViewController.H

@property (nonatomic) UIBackgroundTaskIdentifier backgroundTask;

ViewController.M

self.backgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{

        NSLog(@"Background handler called. Not running background taxsks anymore.");

        [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask];

        self.backgroundTask = UIBackgroundTaskInvalid;

    }];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(countup)userInfo:nil repeats:YES];

        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];

        [[NSRunLoop currentRunLoop] run];

    });

-(void)countup { 

  //Here i done another action run in main thread

 dispatch_async(dispatch_get_main_queue(), ^{  

               ViewController *Vc=[self.storyboard instantiateViewControllerWithIdentifier:@"view"];

                [self.navigationController pushViewController:Vc animated:YES];

            });

}

Assign placeholder image in tableview Cell(Load image asynchrous)

if u Load original image from server,it will take time at that time we show a another image still that original image loaded:

NSURL *imageURL = [NSURL URLWithString:Details.imageUrl];

    cell.imageView.image=[UIImage imageNamed:@"flower.png"];

    

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        

        NSData *data = [NSData dataWithContentsOfURL:imageURL];

        

        if (data) {

            UIImage *offersImage = [UIImage imageWithData:data];

            if (offersImage) {

                dispatch_async(dispatch_get_main_queue(), ^{

                    UITableViewCell *updateCell = [tableView cellForRowAtIndexPath:indexPath];

                    

                    if (updateCell) {

                        updateCell.imageView.image = offersImage;

                    }

                });

            }

        }

    });

show html file in webview

 NSString * localHtmlFilePath =[[NSBundle mainBundle]pathForResource:@"frnd " ofType:@"html"];

    NSString *html = [NSString stringWithContentsOfFile:localHtmlFilePath encoding:NSUTF8StringEncoding error:nil];

   [webview loadHTMLString:html baseURL:nil];

Navigation concepts

//Change the Title Image in  navigation bar:

self.navigationItem.titleView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"flower.png"]];

//Checking version 6 or 7 for changing background color of navigation bar

 NSString *version = [[UIDevice currentDevice] systemVersion];

    if ([version floatValue] < 7) { 

        self.navigationController.navigationBar.barTintColor=[UIColor blackColor];

    } else {

        self.navigationController.navigationBar.tintColor=[UIColor blackColor];

    }

//Hide the back button

    [self.navigationItem setHidesBackButton:YES animated:YES];

//Create custom Back button:

UIButton* customBackButton = [UIButton buttonWithType:101];

    [customBackButton setTitle:@"Back" forState:UIControlStateNormal];

    [customBackButton addTarget:self action:@selector(done:) forControlEvents:UIControlEventTouchUpInside];

    UIBarButtonItem    *myBackButton = [[UIBarButtonItem alloc] initWithCustomView:customBackButton];

    self.navigationItem.backBarButtonItem=myBackButton;

//Create Right bar button: (more than one button)

UIBarButtonItem* allFriends = [[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"frnds.png"] style:UIBarButtonItemStyleBordered target:self action:@selector(allfrnd:)];

    

    UIBarButtonItem* setting = [[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"options.png"] style:UIBarButtonItemStyleBordered target:self action:@selector(setting)];

    self.navigationItem.rightBarButtonItems=@[setting,allFriends];

//Programmatically pushing a root view controller it embedded with navigation controller

ViewController *user=[self.storyboard instantiateViewControllerWithIdentifier:@"user"];

                UINavigationController *navigationController = [[UINavigationController alloc]initWithRootViewController:user];

                [self.navigationController presentViewController:navigationController animated:YES completion:nil];

Get current Location using googlemaps

[GMSServices provideAPIKey:@"AIzaSyAemkuHXhydxhR286ECVVtspCVTstmgBQM"]; // This key is used for Google Maps.

    // Codes to start tracking the location of the user.

    locationManager = [[CLLocationManager alloc] init];

    locationManager.delegate = self;

    locationManager.distanceFilter = kCLDistanceFilterNone;

    locationManager.desiredAccuracy = kCLLocationAccuracyBest;

    [locationManager startUpdatingLocation];

    return YES;

}

- (void)locationManager:(CLLocationManager *)manager

     didUpdateLocations:(NSArray *)locations {

    CLLocation *clLocation = [locations lastObject];

    NSLog(@"Current latitude %f",clLocation.coordinate.latitude);

    NSLog(@"Current longitude %f",clLocation.coordinate.longitude);

}

Refer:https://developers.google.com/maps/documentation/ios/start

Convert TimeStamp into date

    double time=[timeStamp doubleValue]/1000;

    NSTimeInterval _interval=time;

    NSDate *date = [NSDate dateWithTimeIntervalSince1970:_interval];

    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];

    [formatter setDateFormat:@"dd/MM/yyyy hh:mm"];

    NSString *dateString=[formatter stringFromDate:date];