iOS Events and Notifications

iOS Events & Notifications

1.   UIApplicationDelegate

2.   UIApplication Events

3.   Image Capturing

4.   UIWebView

5.   NSUserDefaults & Setting Bundle

6.   Local Notification

7.   Introduction to APN

UIApplicationDelegate:

application:didFinishLaunchingWithOptions:

application

The delegating application object.

launchOptions

A dictionary indicating the reason the application was launched (if any). The contents of this dictionary may be empty in situations where the user launched the application directly. See “Launch Options Keys” in UIApplication Class Reference for descriptions of these keys.

application:didReceiveLocalNotification:

Sent to the delegate when a running application receives a local notification.

application

The application that received the local notification.

notification

A local notification that encapsulates details about the notification, potentially including custom data.

applicationDidBecomeActive:

Tells the delegate that the application has become active.

This method is called to let your application know that it moved from the inactive to active state. This can occur because your application was launched by the user or the system. Applications can also return to the active state if the user chooses to ignore an interruption (such as an incoming phone call or SMS message) that sent the application temporarily to the inactive state.

applicationDidEnterBackground:

Tells the delegate that the application is now in the background.

applicationDidReceiveMemoryWarning:

Tells the delegate when the application receives a memory warning from the system.

applicationWillEnterForeground:

Tells the delegate that the application is about to enter the foreground.

applicationWillResignActive:

Tells the delegate that the application is about to become inactive.

applicationWillTerminate:

Tells the delegate when the application is about to terminate.

UIApplication Events:

-sendEvent:

Subclasses may override this method to intercept incoming events for inspection and special dispatching. iOS calls this method for public events only.

-sendAction:to:from:forEvent:

Normally, this method is invoked by a UIControl object that the user has touched. The default implementation dispatches the action method to the given target object or, if no target is specified, to the first responder. Subclasses may override this method to perform special dispatching of action messages.

-beginIgnoringInteractionEvents:

Tells the receiver to suspend the handling of touch-related events.You typically call this method before starting an animation or transition. Calls are nested with the endIgnoringInteractionEvents method.

-endIgnoringInteractionEvents:

Tells the receiver to resume the handling of touch-related events.You typically call this method when, after calling the beginIgnoringInteractionEvents method, the animation or transition concludes. Nested calls of this method should match nested calls of the beginIgnoringInteractionEvents method.

-isIgnoringInteractionEvents:

Returns whether the receiver is ignoring events initiated by touches on the screen.

Image Capture

 

The UIImagePickerController class manages customizable, system-supplied user interfaces for taking pictures and movies on supported devices, and for choosing saved images and movies for use in your app. An image picker controller manages user interactions and delivers the results of those interactions to a delegate object.

The role and appearance of an image picker controller depend on the source type you assign to it before you present it.

·    A sourceType of UIImagePickerControllerSourceTypeCamera provides a user interface for taking a new picture or movie (on devices that support media capture).

·    A sourceType of UIImagePickerControllerSourceTypePhotoLibrary or UIImagePickerControllerSourceTypeSavedPhotosAlbum provides a user interface for choosing among saved pictures and movies.

To use an image picker controller containing its default controls, perform these steps:

1.  Verify that the device is capable of picking content from the desired source. Do this calling the isSourceTypeAvailable: class method, providing a constant from the “UIImagePickerControllerSourceType” enum.

2.  Check which media types are available, for the source type you’re using, by calling the availableMediaTypesForSourceType: class method. This lets you distinguish between a camera that can be used for video recording and one that can be used only for still images.

3.  Tell the image picker controller to adjust the UI according to the media types you want to make available—still images, movies, or both—by setting the mediaTypes property.

4.  Present the user interface by calling the presentViewController:animated:completion: method of the currently active view controller, passing your configured image picker controller as the new view controller.

On iPad, present the user interface using a popover. Doing so is valid only if the sourceType property of the image picker controller is set to UIImagePickerControllerSourceTypeCamera.

5.  When the user taps a button to pick a newly captured or saved image or movie, or cancels the operation, dismiss the image picker using your delegate object. For newly captured media, your delegate can then save it to the Camera Roll on the device. For previously saved media, your delegate can then use the image data according to the purpose of your app.

Mail Component:

canSendMail

Returns a Boolean indicating whether the current device is able to send email.

setSubject:

Sets the initial text for the subject line of the email.

setToRecipients:

Sets the initial recipients to include in the email’s “To” field.

 

 

MFMailComposeViewControllerDelegate:

mailComposeController:didFinishWithResult:error:

Tells the delegate that the user wants to dismiss the mail composition view.

controller

The view controller object managing the mail composition view.

result

The result of the user’s action.

error

If an error occurred, this parameter contains an error object with information about the type of failure.

e.g.

         picker = [[MFMailComposeViewController alloc] init];

       picker.mailComposeDelegate = self;

       [picker setTitle:@"Email"];

      [picker setSubject:emailSubject];

       [picker setMessageBody:emailBody isHTML:NO];

      

      picker.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;

       picker.modalPresentationStyle = UIModalPresentationFormSheet;

       [self presentModalViewController:picker animated:YES];

NSUserDefaults & Setting Bundle:

Saving:

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// saving an NSString
[prefs setObject:@"TextToSave" forKey:@"keyToLookupString"];

// saving an NSInteger
[prefs setInteger:42 forKey:@"integerKey"];

// saving a Double
[prefs setDouble:3.1415 forKey:@"doubleKey"];

// saving a Float
[prefs setFloat:1.2345678 forKey:@"floatKey"];

// This is suggested to synch prefs, but is not needed (I didn't put it in my tut)
[prefs synchronize];

Retrieving

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// getting an NSString
NSString *myString = [prefs stringForKey:@"keyToLookupString"];

// getting an NSInteger
NSInteger myInt = [prefs integerForKey:@"integerKey"];

// getting an Float
float myFloat = [prefs floatForKey:@"floatKey"];

Control type

Description

Text field

The text field type displays a title (optional) and an editable text field. You can use this type for preferences that require the user to specify a custom string value.

The key for this type is PSTextFieldSpecifier.

Title

The title type displays a read-only string value. You can use this type to display read-only preference values. (If the preference contains cryptic or nonintuitive values, this type lets you map the possible values to custom strings.)

The key for this type is PSTitleValueSpecifier.

Toggle switch

The toggle switch type displays an ON/OFF toggle button. You can use this type to configure a preference that can have only one of two values. Although you typically use this type to represent preferences containing Boolean values, you can also use it with preferences containing non-Boolean values.

The key for this type is PSToggleSwitchSpecifier.

Slider

The slider type displays a slider control. You can use this type for a preference that represents a range of values. The value for this type is a real number whose minimum and maximum value you specify.

The key for this type is PSSliderSpecifier.

Multivalue

The multivalue type lets the user select one value from a list of values. You can use this type for a preference that supports a set of mutually exclusive values. The values can be of any type.

The key for this type is PSMultiValueSpecifier.

Group

The group type is for organizing groups of preferences on a single page. The group type does not represent a configurable preference. It simply contains a title string that is displayed immediately before one or more configurable preferences.

The key for this type is PSGroupSpecifier.

Child pane

The child pane type lets the user navigate to a new page of preferences. You use this type to implement hierarchical preferences. For more information on how you configure and use this preference type, see “Hierarchical Preferences.”

The key for this type is PSChildPaneSpecifier.

Configuring a Settings Page: A Tutorial

This section shows you how to configure a Settings page to display the controls you want.

1.  Disclose the Preference Items key to display the default items that come with the template.

2.  Change the title of Item 0 to Sound.

·    Disclose Item 0 of Preference Items.

·    Change the value of the Title key from Group to Sound.

·    Leave the Type key set to Group.

·    Click the disclosure triangle of the item to hide its contents.

3.  Create the first toggle switch for the renamed Sound group.

·    Select Item 2 (the toggle switch item) of Preference Items and choose Edit > Cut.

·    Select Item 0 and choose Edit > Paste. (This moves the toggle switch item in front of the text field item.)

·    Disclose the toggle switch item to reveal its configuration keys.

·    Change the value of the Title key to Play Sounds.

·    Change the value of the Identifier key to play_sounds_preference.

·    Click the disclosure triangle of the item to hide its contents.

4.  Create a second toggle switch for the Sound group.

·    Select Item 1 (the Play Sounds toggle switch).

·    Choose Edit > Copy.

·    Choose Edit >Paste to place a copy of the toggle switch right after the first one.

·    Disclose the new toggle switch item to reveal its configuration keys.

·    Change the value of its Title key to 3D Sound.

·    Change the value of its Identifier key to 3D_sound_preference.

·    Click the disclosure triangle of the item to hide its contents.

At this point, you have finished the first group of settings and are ready to create the User Info group.

5.  Change Item 3 into a Group control and name it User Info.

·    Click Item 3 in the Preferences Items. This displays a pop-up menu with a list of item types.

·    From the pop-up menu, choose Group to change the type of the control.

·    Disclose the contents of Item 3.

·    Set the value of the Title key to User Info.

·    Click the disclosure triangle of the item to hide its contents.

6.  Create the Name field.

·    Select Item 4 in the Preferences Items.

·    Using the pop-up menu, change its type to Text Field.

·    Set the value of the Title key to Name.

·    Set the value of the Identifier key to user_name.

·    Click the disclosure triangle of the item to hide its contents.

7.  Create the Experience Level settings.

·    Select Item 4.

·    Control-click the editor window and select Add Row to add a new item.

·    Set the type of the new item to Multi Value.

·    Disclose the item’s contents and set its title to Experience Level, its identifier to experience_preference, and its default value to 0.

·    With the Default Value key selected, Control-click and select Add Row to add a Titles array.

·    Select the Titles array and press Return to add a new subitem.

·    Add two more subitems to create a total of three items.

·    Set the values of the subitems to Beginner, Expert, and Master.

·    Hide the key’s subitems.

·    Add a new item for the Values array.

·    Add three subitems to the Values array and set their values to 0, 1, and 2.

·    Hide the contents of Item 5.

8.  Add the final group to your settings page.

·    Create a new item and set its type to Group and its title to Gravity.

·    Create another new item and set its type to Slider, its identifier to gravity_preference, its default value to 1, and its maximum value to 2.

UIWebView:

1. use the UIWebView class to embed web content in your application. To do so, you simply create a UIWebView object, attach it to a window, and send it a request to load web content. You can also use this class to move back and forward in the history of webpages, and you can even set some web content properties programmatically.

2. Use the loadRequest: method to begin loading web content, the stopLoading method to stop loading, and the loading property to find out if a web view is in the process of loading.

3.Loading a document into a UIWebView.

-(void)loadDocument:(NSString*)documentName inView:(UIWebView*)webView {     NSString *path = [[NSBundle mainBundle] pathForResource:documentName ofType:nil];     NSURL *url = [NSURL fileURLWithPath:path];     NSURLRequest *request = [NSURLRequest requestWithURL:url];     [webView loadRequest:request]; } // Calling -loadDocument:inView: [self loadDocument:@"mydocument.rtfd.zip" inView:self.myWebview];

loadHTMLString:baseURL:

Sets the main page content and base URL.

- (void)loadHTMLString:(NSString *)string baseURL:(NSURL *)baseURL

reload

Reloads the current page.

StopLoading

Stops the loading of any web content managed by the receiver.

StringByEvaluatingJavaScriptFromString:

Returns the result of running a script.

Scheduling Local Notifications

Creating and scheduling local notifications in iOS requires that you perform a few simple steps:

1.  Allocate and initialize a UILocalNotification object.

2.  Set the date and time that the operating system should deliver the notification. This is the fireDate property.

If you set the timeZone property to the NSTimeZone object for the current locale, the system automatically adjusts the fire date when the device travels across (and is reset for) different time zones. (Time zones affect the values of date components—that is, day, month, hour, year, and minute—that the system calculates for a given calendar and date value.) You can also schedule the notification for delivery on a recurring basis (daily, weekly, monthly, and so on).

3.  Configure the substance of the notification: alert, icon badge number, and sound.

·    The alert has a property for the message (the alertBody property) and for the title of the action button or slider (alertAction); both of these string values can be internationalized for the user’s current language preference.

·    You set the badge number to display on the application icon through the applicationIconBadgeNumber property.

·    You can assign the filename of a nonlocalized custom sound in the application’s main bundle to the soundName property; to get the default system sound, assign UILocalNotificationDefaultSoundName. Sounds should always accompany an alert message or icon badging; they should not be played otherwise.

4.  Optionally, you can attach custom data to the notification through the userInfo property.

Keys and values in the userInfo dictionary must be property-list objects.

5.  Schedule the local notification for delivery.

You schedule a local notification by calling the UIApplication method scheduleLocalNotification:. The application uses the fire date specified in the UILocalNotification object for the moment of delivery. Alternatively, you can present the notification immediately by calling the presentLocalNotificationNow: method.

- (void)scheduleNotificationWithItem:(ToDoItem *)item interval:(int)minutesBefore {

    NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];

    NSDateComponents *dateComps = [[NSDateComponents alloc] init];

    [dateComps setDay:item.day];

    [dateComps setMonth:item.month];

    [dateComps setYear:item.year];

    [dateComps setHour:item.hour];

    [dateComps setMinute:item.minute];

    NSDate *itemDate = [calendar dateFromComponents:dateComps];

    [dateComps release];

    UILocalNotification *localNotif = [[UILocalNotification alloc] init];

    if (localNotif == nil)

        return;

    localNotif.fireDate = [itemDate addTimeInterval:-(minutesBefore*60)];

    localNotif.timeZone = [NSTimeZone defaultTimeZone];

    localNotif.alertBody = [NSString stringWithFormat:NSLocalizedString(@"%@ in %i minutes.", nil),

         item.eventName, minutesBefore];

    localNotif.alertAction = NSLocalizedString(@"View Details", nil);

    localNotif.soundName = UILocalNotificationDefaultSoundName;

    localNotif.applicationIconBadgeNumber = 1;

    NSDictionary *infoDict = [NSDictionary dictionaryWithObject:item.eventName forKey:ToDoItemKey];

    localNotif.userInfo = infoDict;

    [[UIApplication sharedApplication] scheduleLocalNotification:localNotif];

    [localNotif release];

}

APN:

 A push notification from a provider to a client application

Figure 3-1 is a greatly simplified depiction of the virtual network APNs makes possible among providers and devices. The device-facing and provider-facing sides of APNs both have multiple points of connection; on the provider-facing side, these are called gateways. There are typically multiple providers, each making one or more persistent and secure connections with APNs through these gateways. And these providers are sending notifications through APNs to many devices on which their client applications are installed. Figure 3-2 is a slightly more realistic depiction.

Figure 3-2  Push notifications from multiple providers to multiple devices