iPhone App Development Tutorial – Add an Intro View to a Tab Bar App

This tutorial is on adding an intro view to your app. In this instance we’ll be adding it to a tab bar app. This is not the use of a splash view. A splash view is one which is shown each time an app loads and is only shown for a few short seconds, going away without any user interaction. Our intro view will be one that is shown at a specific time, mostly when the app is loaded for the first time. The view will stay visible until the user takes some action to dismiss the view. We will be showing our view modally and using a boolean to determine whether to show the view when the app is loaded. In addition we will be storing the boolean in a plist and loading it’s value to determine whether to show our intro view.

So now that we’ve laid out what we want to do, let’s get started.

1.) Let’s start by creating a tab app and naming it IntroViewTutorial. I don’t really like to use the Storyboard, but definitely use Automatic Reference Counting.

2.) The first thing we’ll do is add the plist and create a Boolean. Select New > New File > Resource > Property List, and name it IntroViewData.plist

3.) After creating the plist, open it up and add a Boolean value. You can do this by either right clicking in the file and selecting Add Row.

Or with the plist selected,

Go to the Editor menu and select Add Item.

Create the item with a Key of showIntroView, make it a Boolean, and give it an initial value of YES.

Save the plist.

4.) Next we’re going to change the FirstViewController.xib. Deleted the labels and add two buttons.

5.) Open FirstViewController.m and we’ll implement the plist methods. We’re going to add two IBActions that we’ll call from the buttons. These methods save a value in plist. I could have combined these into one method, but decided to keep it simple for now.

- (IBAction)showIntroView
{
    // get paths from root directory
    NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
    // get documents path
    NSString *documentsPath = [paths objectAtIndex:0];
    // get the path to our Data/plist file
    NSString *plistPath = [documentsPath stringByAppendingPathComponent:@"IntroViewData.plist"];
    
    Boolean noBool = YES;
    
    // create dictionary with values in UITextFields
    NSDictionary *plistDict = [NSDictionary dictionaryWithObjects: [NSArray arrayWithObjects: [NSNumber numberWithBool:noBool], nil] forKeys:[NSArray arrayWithObjects: @"showIntroView", nil]];
    
    NSString *error = nil;
    // create NSData from dictionary
    NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:plistDict format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];
    
    // check is plistData exists
    if(plistData)
    {
        // write plistData to our Data.plist file
        [plistData writeToFile:plistPath atomically:YES];
    }
    else
    {
        NSLog(@"Error in saveToPlist, IntroViewData does not exist: %@", error);
    }
}

- (IBAction)dontShowIntroView
{
    // get paths from root directory
    NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
    // get documents path
    NSString *documentsPath = [paths objectAtIndex:0];
    // get the path to our Data/plist file
    NSString *plistPath = [documentsPath stringByAppendingPathComponent:@"IntroViewData.plist"];
    
    Boolean yesBool = NO;
    
    // create dictionary with values in UITextFields
    NSDictionary *plistDict = [NSDictionary dictionaryWithObjects: [NSArray arrayWithObjects: [NSNumber numberWithBool:yesBool], nil] forKeys:[NSArray arrayWithObjects: @"showIntroView", nil]];
    
    NSString *error = nil;
    // create NSData from dictionary
    NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:plistDict format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];
    
    // check is plistData exists
    if(plistData)
    {
        // write plistData to our Data.plist file
        [plistData writeToFile:plistPath atomically:YES];
    }
    else
    {
        NSLog(@"Error in saveToPlist, IntroViewData does not exist: %@", error);
    }
}

After creating the IBActions, hook them up to the buttons in the view.

6.) Now that we are saving a value into the plist let’s access that value in the app delegate and read it. We’ll starts by just writing the value to the console. We read in the plist in the application:didFinishLaunchingWithOptions method.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    
    // setting up the tabs
    UIViewController *viewController1 = [[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil];
    UIViewController *viewController2 = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
    self.tabBarController = [[UITabBarController alloc] init];
    self.tabBarController.viewControllers = [NSArray arrayWithObjects:viewController1, viewController2, nil];
    self.window.rootViewController = self.tabBarController;
    [self.window makeKeyAndVisible];
    
    // ^^^^^^^^^^^^^^^^^^^^^^^^^^^ plist section ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    // IntroViewData.plist code
    // get paths from root direcory
    NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
    // get documents path
    NSString *documentsPath = [paths objectAtIndex:0];
    // get the path to our data/plist file
    NSString *plistPath = [documentsPath stringByAppendingPathComponent:@"IntroViewData.plist"];
    
    // check to see if Data.plist exists in documents
    if (![[NSFileManager defaultManager] fileExistsAtPath:plistPath])
    {
        // if not in documents, get property list from main bundle
        plistPath = [[NSBundle mainBundle] pathForResource:@"IntroViewData" ofType:@"plist"];
    }
    
    // read property list into memory as an NSData object
    NSData *plistXML = [[NSFileManager defaultManager] contentsAtPath:plistPath];
    NSString *errorDesc = nil;
    NSPropertyListFormat format;
    // convert static property list into dictionary object
    NSDictionary *temp = (NSDictionary *)[NSPropertyListSerialization propertyListFromData:plistXML mutabilityOption:NSPropertyListMutableContainersAndLeaves format:&format errorDescription:&errorDesc];
    if (!temp)
    {
        NSLog(@"Error reading plist: %@, format: %d", errorDesc, format);
    }
    
    BOOL showIntroView = [[temp objectForKey:@"showIntroView"] boolValue];
    
    // ^^^^^^^^^^^^^^^^^^^^^^^^^^^ end plist section ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    
    NSLog(@"showIntroView = %d", showIntroView);
    
    return YES;
}

When we print the value to the console it will be represented by a decimal, 1 for YES, and 0 for NO.

You can run the app at this point and check the console, click the buttons to change the value, close the app, run it again and see that the value is being saved in the plist.

7.) Now let’s create our Intro View. Select File > New File > UIViewController subview and name it IntroViewController. Open the xib and add a button that will dismiss the view.

8.) Open the IntroViewController.m file and add a method to dismiss the modal view.

- (IBAction)dismissTheModalView
{
    [self dismissModalViewControllerAnimated:YES];
}

Then connect it the button in the view.

9.) Open the app delegate implementation file and import our new IntroViewController.

#import "IntroViewController.h"

Then declare a IntroViewController and add an if block to check for the Boolean value we saved into the plist. If the value it true we’ve display our intro view modally.

 IntroViewController *introView = [[IntroViewController alloc] initWithNibName:@"IntroViewController" bundle:[NSBundle mainBundle]];
    
if (showIntroView) 
{
	[self.window.rootViewController presentModalViewController:introView animated:NO];
}

That is all there is to it. Run the app and try it out. I’m currently working on an app that shows a list in a table view, but only after the user adds some data to be shown in the table. So I show the intro view only when there is not data saved to be shown in the table. If there is data saved the app goes straight to the table.

Here’s the code.