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Sometimes we need to check synchronously, if there is an internet connection. For instance, when an app totally depends on internet connection. This is the simplest way to check internet connection on iOS app synchronously without using Reachability class:

NSURL *url = [NSURL URLWithString:@"http://www.google.com"];
NSData *data = [NSData dataWithContentsOfURL:url];
if (data != nil)
    NSLog(@"Device is connected to the internet");
else
    NSLog(@"Device is not connected to the internet");

Taken from here.

Instead of Google it is better to use another lightweight website. But I use google.com, since it is always online and reliable and not very heavy page.

If you just set only a self.title and self.tabBarItem.title, your tabBarItem title will change to the title of navigation controller.
So, this is the solution, taken from StackOverflow:

self.title = @"Title for TabBarItem";
 // TabBarItem.title inherits the viewController's self.title
self.navigationItem.title = @"Title for NavigationBar";

Recently I was shocked by the fact that two NSStrings that resemble each other on NSLog may be different. It is because sometimes NSString can contain a zero width space character. Be aware of that and consider:

    #define ZERO_WIDTH_SPACE_STRING @"\u200B"

To conquer this you should clean your string from zero width white space characters before comparing:

    NSMutableString *eMailToAdd = [NSMutableString string];
	
    NSMutableCharacterSet *charSet = \
[[NSCharacterSet whitespaceCharacterSet] mutableCopy];
    	//[charSet formUnionWithCharacterSet:\
[NSCharacterSet punctuationCharacterSet]];
    	
        NSString *rawStr = [[tokenField textField] text];
    	for (int i = 0; i < [rawStr length]; i++)
    	{
    		if (![charSet characterIsMember:\
[rawStr characterAtIndex:i]])
    		{
    			[eMailToAdd appendFormat:\
@"%@",[NSString stringWithFormat:@"%c",\
 [rawStr characterAtIndex:i]]];
    		}
    	}

Sometimes it is hard to use resignFirstResponder method on every textField, that is present on our view. It is much easier to hide keyboard by the following way:

[self.view endEditing:YES];

To change a delete button title use this:

- (NSString *)tableView:(UITableView *)tableView \
 titleForDeleteConfirmationButtonForRowAtIndexPath: \
(NSIndexPath *)indexPath {
    
    return @"Удалить из избранного";
    
}

To change a background color of a grouped table view in iOS we need to do two things:

self.tableView.backgroundColor = your_color;
self.tableView.backgroundView = nil;

It is the third answer here.

Animation pattern using blocks:

    [UIView animateWithDuration:1.0
                     animations:^{
                         
                     }
                     completion:^(BOOL finished){
                         
                     }
     ];

I will explain, how to create an animation, when you Default image comes to front with dissolving.

To create an animated Intro View in iOS App, which has a TabBarController you may do the following:

1. Create an Intro View Controller, which has one UIImageView with your Default.png.
2. Add the following to your application didFinishLaunchingWithOptions method

   IntroViewController *introViewController = \
   [[IntroViewController alloc] initWithNibName: \
   @"IntroViewController" bundle:nil];
       self.window.rootViewController = introViewController;
       
       [self.window makeKeyAndVisible];
   

3. Add the following method to your IntroViewController:

   - (void)viewDidAppear:(BOOL)animated
   {
       [super viewDidAppear:animated];
       
       [UIView animateWithDuration:0.5
                        animations:^{
                            CGRect frame = self.imageView.frame;
                            frame.origin.x -= frame.size.width;
                            frame.origin.y -= frame.size.height;
                            frame.size.width *= 3;
                            frame.size.height *= 3;
                            self.imageView.frame = frame;
                            self.imageView.alpha = 0.0;
                        }
                        completion:^(BOOL finished){
                            useDelegate
                            appDelegate.window.rootViewController = \
   appDelegate.tabBarController;
                        }
       ];
   }
   

Explanation:
After app loads, Intro View Controller is diplayed. Then, when it’s view appears, it’s UIImageView’s frame is trippled in size and it’s origin is moved to top left. Also the transparency is changed to 100%. After animation finishes, your tab bar controller is displayed.