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→Running the UIPageViewController Application
With the data source implemented, the next step is to create and initialize an instance of the UIPageViewController class.
== Initializing the UIPageViewController ==
All that remains is to create the UIPageViewController instance and initialize it appropriately. Since this needs to be performed only once per application invocation a suitable location for this code is the viewDidLoad method of the PageAppViewController class. Select the PageAppViewController.m file and modify the viewDidLoad method so that it reads as follows:
<pre>
- (void)viewDidLoad
{
[super viewDidLoad];
[self createContentPages];
NSDictionary *options = [NSDictionary dictionaryWithObject:
[NSNumber numberWithInteger:UIPageViewControllerSpineLocationMin]
forKey: UIPageViewControllerOptionSpineLocationKey];
_pageController = [[UIPageViewController alloc]
initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl
navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal
options: options];
_pageController.dataSource = self;
[[_pageController view] setFrame:[[self view] bounds]];
ContentViewController *initialViewController =
[self viewControllerAtIndex:0];
NSArray *viewControllers =
[NSArray arrayWithObject:initialViewController];
[_pageController setViewControllers:viewControllers
direction:UIPageViewControllerNavigationDirectionForward
animated:NO
completion:nil];
[self addChildViewController:_pageController];
[[self view] addSubview:[_pageController view]];
[_pageController didMoveToParentViewController:self];
}
</pre>
All the code for the application is now complete. Before compiling and running the application some time needs to be taken to deconstruct and analyze the code in the viewDidLoad method.
After constructing the data model with the call to the createContentPage method an NSDictionary object is created to contain the options that will be applied to the page controller object. In this instance the only option used is to set the spine location to appear on the left of the screen:
<pre>
NSDictionary *options =
[NSDictionary dictionaryWithObject:
[NSNumber numberWithInteger:UIPageViewControllerSpineLocationMin]
forKey: UIPageViewControllerOptionSpineLocationKey];
</pre>
Next, an instance of the UIPageViewController class is created using the previously created options object and specifying horizontal navigation orientation:
<pre>
_pageController = [[UIPageViewController alloc]
initWithTransitionStyle:UIPageViewControllerTransitionStylePageCurl
navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal
options: options];
</pre>
Since the current class is going to act as the data source for the page controller this also needs to be configured. We also want the pages to fill the entire screen, so need to set the bounds appropriately:
<pre>
_pageController.dataSource = self;
[[_pageController view] setFrame:[[self view] bounds]];
</pre>
Before the first page can be displayed a view controller must first be created. This can be achieved by calling our viewControllerAtIndex: convenience method. Once a content view controller has been returned it needs to be assigned to an array object:
<pre>
ContentViewController *initialViewController =
[self viewControllerAtIndex:0];
NSArray *viewControllers =
[NSArray arrayWithObject:initialViewController];
</pre>
Note that only one content view controller is needed because the page controller is configured to display only one, single sided page at a time. Had the page controller been configured for two pages (with a mid location spine) or for double sided pages it would have been necessary to create two content view controllers at this point and assign both to the array.
With an array containing the content view controller ready, the array needs to be assigned to the view controller with the navigation direction set to forward mode:
<pre>
[_pageController setViewControllers:viewControllers
direction:UIPageViewControllerNavigationDirectionForward
animated:NO
completion:nil];
</pre>
Finally, the standard steps need to be taken to add the page view controller to the current view:
<pre>
[self addChildViewController:_pageController];
[[self view] addSubview:[_pageController view]];
[_pageController didMoveToParentViewController:self];
</pre>
== Running the UIPageViewController Application ==
