主从分割视图

Question

我有一个iPhone应用程序，想要制作一个通用应用程序并在iPad上实现拆分视图。 我设置了主视图，以便当用户选择一行时，主视图转到另一个表视图。 在该表视图中选择一行时，我希望详细视图显示我的Web视图。 所有这些都有效，但是我遇到的问题是当Web视图显示在详细视图上时，它只是被添加到导航堆栈中，而不仅仅是替换当前存在的内容。 这样一来，用户就必须按下详细视图导航栏上的“后退”按钮，以便在主视图中进行其他选择。 如果在主视图中进行了其他选择而未按详细视图上的“后退”按钮，则应用程序将崩溃。

我需要弄清楚如何不将Web视图添加到详细信息视图的导航堆栈中，而是替换当前的详细信息视图。

MasterViewController：

#import "KFBMasterViewController.h"
#import "KFBDetailViewController.h"
#import "ListViewController.h"
#import "SocialNetworks.h"
#import "WebViewController.h"

@interface KFBMasterViewController () {
    NSMutableArray *_objects;
    NSMutableArray *menu;
}
@end

@implementation KFBMasterViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        self.title = NSLocalizedString(@"Master", @"Master");
        self.clearsSelectionOnViewWillAppear = NO;
        self.contentSizeForViewInPopover = CGSizeMake(320.0, 600.0);
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    // self.navigationItem.leftBarButtonItem = self.editButtonItem;

    // UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject:)];
    // self.navigationItem.rightBarButtonItem = addButton;

    menu = [NSMutableArray arrayWithObjects:@"Home", @"Public Affairs", @"Action Alerts", @"Market Updates", @"Ag Stories", @"KFB News", @"Member Benefits", @"Monthly Video", @"Photos", @"Social Media", @"About Us", @"Contact Us", @"KYFB.com", nil];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)insertNewObject:(id)sender
{
    if (!_objects) {
        _objects = [[NSMutableArray alloc] init];
    }
    [_objects insertObject:[NSDate date] atIndex:0];
    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
    [self.tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
}

#pragma mark - Table View

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return menu.count;
}

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }


    // NSDate *object = _objects[indexPath.row];
    // cell.textLabel.text = [object description];
    cell.textLabel.text = [menu objectAtIndex:indexPath.row];
    return cell;
}

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the specified item to be editable.
    return YES;
}

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        [_objects removeObjectAtIndex:indexPath.row];
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
    }
}

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the item to be re-orderable.
    return YES;
}
*/

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // NSDate *object = _objects[indexPath.row];
    // self.detailViewController.detailItem = object;

    // KFBDetailViewController *detailViewController = (KFBDetailViewController*)self.splitViewController.delegate;

    // UIViewController <SubstitutableDetailViewController> *detailViewController = nil;

    if (indexPath.row == 1)
    {
        // [((UINavigationController *)[self.splitViewController.viewControllers lastObject]) pushViewController:[[ListViewController alloc]initWithStyle:UITableViewStylePlain] animated:YES];
        // [[self.splitViewController.viewControllers lastObject] pushViewController:[[ListViewController alloc]initWithStyle:UITableViewStylePlain] animated:YES];

        // ListViewController *publicAffairs = [[ListViewController alloc] initWithNibName:nil bundle:[NSBundle  mainBundle]];
        // [self.navigationController pushViewController:publicAffairs animated:YES];

        ListViewController *publicAffairs = [[ListViewController alloc]initWithStyle:UITableViewStylePlain];
        WebViewController *wvc = [[WebViewController alloc]init];
        [publicAffairs setWebViewController:wvc];
        publicAffairs.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
        [self.navigationController pushViewController:publicAffairs animated:YES];
        // [self presentViewController:publicAffairs animated:YES completion:nil];
    }
    else if (indexPath.row == 9)
    {
        // [((UINavigationController *)[self.splitViewController.viewControllers lastObject]) pushViewController:[[SocialNetworks alloc]initWithNibName:@"SocialNetworks" bundle:nil] animated:YES];
        // [[self.splitViewController.viewControllers lastObject] pushViewController:[[SocialNetworks alloc]initWithNibName:@"SocialNetworks" bundle:nil] animated:YES];

        SocialNetworks *social = [[SocialNetworks alloc] initWithNibName:@"SocialNetworks" bundle:[NSBundle  mainBundle]];
        [self.navigationController pushViewController:social animated:YES];
    }
}

@end

DetailViewController：

#import "KFBDetailViewController.h"

@interface KFBDetailViewController ()
@property (strong, nonatomic) UIPopoverController *masterPopoverController;
- (void)configureView;
@end

@implementation KFBDetailViewController

#pragma mark - Managing the detail item

- (void)setDetailItem:(id)newDetailItem
{
    if (_detailItem != newDetailItem) {
        _detailItem = newDetailItem;

        // Update the view.
        [self configureView];
    }

    if (self.masterPopoverController != nil) {
        [self.masterPopoverController dismissPopoverAnimated:YES];
    }        
}

- (void)configureView
{
    // Update the user interface for the detail item.

    if (self.detailItem) {
        self.detailDescriptionLabel.text = [self.detailItem description];
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self configureView];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        self.title = NSLocalizedString(@"Detail", @"Detail");
    }
    return self;
}

#pragma mark - Split view

- (void)splitViewController:(UISplitViewController *)splitController willHideViewController:(UIViewController *)viewController withBarButtonItem:(UIBarButtonItem *)barButtonItem forPopoverController:(UIPopoverController *)popoverController
{
    barButtonItem.title = NSLocalizedString(@"Master", @"Master");
    [self.navigationItem setLeftBarButtonItem:barButtonItem animated:YES];
    self.masterPopoverController = popoverController;
}

- (void)splitViewController:(UISplitViewController *)splitController willShowViewController:(UIViewController *)viewController invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem
{
    // Called when the view is shown again in the split view, invalidating the button and popover controller.
    [self.navigationItem setLeftBarButtonItem:nil animated:YES];
    self.masterPopoverController = nil;
}

@end

ListViewController：

#import "ListViewController.h"
#import "RSSChannel.h"
#import "RSSItem.h"
#import "WebViewController.h"
#import "KFBDetailViewController.h"
// #import "CustomCellBackground.h"

@implementation ListViewController
{
    UIActivityIndicatorView *loadingIndicator;
}
@synthesize webViewController;

- (void)viewDidLoad
{

    self.tableView = [[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStyleGrouped];
    self.title = @"Public Affairs";
    loadingIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
    loadingIndicator.center = CGPointMake(160, 160);
    loadingIndicator.hidesWhenStopped = YES;
    [self.view addSubview:loadingIndicator];
    [loadingIndicator startAnimating];
    // UIRefreshControl *refresh = [[UIRefreshControl alloc] init];
    // refresh.attributedTitle = [[NSAttributedString alloc] initWithString:@"Pull to Refresh"];
    // [refresh addTarget:self action:@selector(refreshView:)forControlEvents:UIControlEventValueChanged];
    // self.refreshControl = refresh;
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    if ([elementName isEqual:@"channel"])
    {
        // If the parser saw a channel, create new instance, store in our ivar
        channel = [[RSSChannel alloc]init];

        // Give the channel object a pointer back to ourselves for later
        [channel setParentParserDelegate:self];

        // Set the parser's delegate to the channel object
        [parser setDelegate:channel];
    }
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // return 0;
    NSLog(@"channel items %d", [[channel items]count]);
    return [[channel items]count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // return nil;

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"UITableViewCell"];
    if (cell == nil)
    {
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"UITableViewCell"];
        cell.textLabel.font=[UIFont systemFontOfSize:16.0];
    }
    RSSItem *item = [[channel items]objectAtIndex:[indexPath row]];

    // cell.backgroundView = [[CustomCellBackground alloc] init];
    // cell.selectedBackgroundView = [[CustomCellBackground alloc] init];
    cell.textLabel.backgroundColor = [UIColor clearColor];
    cell.textLabel.highlightedTextColor = [UIColor darkGrayColor];

    if (item.isActionAlert) {
        NSLog(@"Action Alert...Not Using");
    }
    else
    {
        [[cell textLabel]setText:[item title]];
    }

    return cell;
}

- (void)fetchEntries
{
    // Create a new data container for the stuff that comes back from the service
    xmlData = [[NSMutableData alloc]init];

    // Construct a URL that will ask the service for what you want -
    NSURL *url = [NSURL URLWithString:@"http://kyfbnewsroom.com/category/public-affairs/feed"];

    // Put that URL into an NSURLRequest
    NSURLRequest *req = [NSURLRequest requestWithURL:url];

    // Create a connection that will exchange this request for data from the URL
    connection = [[NSURLConnection alloc]initWithRequest:req delegate:self startImmediately:YES];
}

- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];

    if (self)
    {
        [self fetchEntries];
    }

    return self;
}

// This method will be called several times as the data arrives
- (void)connection:(NSURLConnection *)conn didReceiveData:(NSData *)data
{
    // Add the incoming chunk of data to the container we are keeping
    // The data always comes in the correct order
    [xmlData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)conn
{
    /* We are just checking to make sure we are getting the XML
     NSString *xmlCheck = [[NSString alloc]initWithData:xmlData encoding:NSUTF8StringEncoding];
     NSLog(@"xmlCheck = %@", xmlCheck);*/

    [loadingIndicator stopAnimating];

    // Create the parser object with the data received from the web service
    NSXMLParser *parser = [[NSXMLParser alloc]initWithData:xmlData];

    // Give it a delegate
    [parser setDelegate:self];

    //Tell it to start parsing - the document will be parsed and the delegate of NSXMLParser will get all of its delegate messages sent to it before this line finishes execution - it is blocking
    [parser parse];

    // Get rid of the XML data as we no longer need it
    xmlData = nil;

    // Reload the table.. for now, the table will be empty
    NSMutableArray *actionAlerts = [NSMutableArray array];
    for (RSSItem *object in channel.items) {
        if (object.isActionAlert) {
            [actionAlerts addObject:object];
        }
    }

    for (RSSItem *object in actionAlerts) {
        [channel.items removeObject:object];
    }
    [[self tableView]reloadData];

    NSLog(@"%@\n %@\n %@\n", channel, [channel title], [channel infoString]);
}

- (void)connection:(NSURLConnection *)conn didFailWithError:(NSError *)error
{
    // Release the connection object, we're done with it
    connection = nil;

    // Release the xmlData object, we're done with it
    xmlData = nil;

    // Grab the description of the error object passed to us
    NSString *errorString = [NSString stringWithFormat:@"Fetch failed: %@", [error localizedDescription]];

    // Create and show an alert view with this error displayed
    UIAlertView *av = [[UIAlertView alloc]initWithTitle:@"Error" message:errorString delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [av show];
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{   
    [((UINavigationController *) [self.splitViewController.viewControllers lastObject]) pushViewController:webViewController animated:YES];

    // Grab the selected item
    RSSItem *entry = [[channel items]objectAtIndex:[indexPath row]];

    NSLog(@"Channel Items: %@", [[channel items]objectAtIndex:[indexPath row]]);

    // Construct a URL with the link string of the item
    NSURL *url = [NSURL URLWithString:[entry link]];

    NSLog(@"Link: %@", [entry link]);

    // Construct a request object with that URL
    NSURLRequest *req = [NSURLRequest requestWithURL:url];

    NSLog(@"URL: %@", url);

    // Load the request into the web view
    [[webViewController webView]loadRequest:req];
    webViewController.hackyURL = url;
    NSLog(@"Request: %@", req);

    // Set the title of the web view controller's navigation item
    // [[webViewController navigationItem]setTitle:[entry title]];

    NSLog(@"Title: %@", [entry title]);
}

@end

AppDelegate：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.

    KFBMasterViewController *masterViewController = [[KFBMasterViewController alloc] initWithNibName:@"KFBMasterViewController" bundle:nil];
    UINavigationController *masterNavigationController = [[UINavigationController alloc] initWithRootViewController:masterViewController];

    KFBDetailViewController *detailViewController = [[KFBDetailViewController alloc] initWithNibName:@"KFBDetailViewController" bundle:nil];
    UINavigationController *detailNavigationController = [[UINavigationController alloc] initWithRootViewController:detailViewController];

    masterViewController.detailViewController = detailViewController;

    self.splitViewController = [[UISplitViewController alloc] init];
    self.splitViewController.delegate = detailViewController;
    self.splitViewController.viewControllers = @[masterNavigationController, detailNavigationController];
    self.window.rootViewController = self.splitViewController;
    [self.window makeKeyAndVisible];
    return YES;
}