TableView doesn't push to WebView - objective-c

Question

I'm trying to make an RSS Feed for my website inside the app. I'm trying to make it so that when the user clicks a cell in my TableView it brings you to the link of the specific post parsed. The link is being parsed, but the console gives me this error:
Application tried to push a nil view controller on target .
Here is my code:
WebViewController.h
#import <Foundation/Foundation.h>
#interface WebViewController : UIViewController
#property (nonatomic, readonly) UIWebView *webView;
#end
WebViewController.m
#import "WebViewController.h"
#implementation WebViewController
-(void)loadView
{
CGRect screenFrame = [[UIScreen mainScreen] applicationFrame];
UIWebView *wv = [[UIWebView alloc] initWithFrame:screenFrame];
[wv setScalesPageToFit:YES];
[self setView:wv];
}
-(UIWebView *)webView
{
return (UIWebView *)[self view];
}
#end
MasterViewController.h My TableView
#import <UIKit/UIKit.h>
// A forward declaration; we'll import the header in the .m
#class RSSChannel;
#class WebViewController;
#interface MasterViewController : UITableViewController
<NSXMLParserDelegate>
{
NSURLConnection *connection;
NSMutableData *xmlData;
RSSChannel *channel;
}
#property (strong, nonatomic) IBOutlet UITableView *tableView;
#property (strong, nonatomic) IBOutlet UINavigationItem *navigationBar;
#property (nonatomic, strong) WebViewController *webViewController;
- (void)fetchEntries;
#end
MasterViewController.m
#import "MasterViewController.h"
#import "WebViewController.h"
#import "RSSChannel.h"
#import "RSSItem.h"
#interface MasterViewController () {
NSMutableArray *_objects;
}
#end
#implementation MasterViewController
#synthesize tableView = _tableView;
#synthesize navigationBar;
#synthesize webViewController;
- (void)awakeFromNib
{
[super awakeFromNib];
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self fetchEntries];
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
}
#pragma mark - Table View
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
UIImage *myImage = [UIImage imageNamed:#"SephardiJewsHeader.png"];
UIImageView *imageView = [[UIImageView alloc] initWithImage:myImage];
imageView.frame = CGRectMake(0,-1,320,93);
return imageView;
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
return 93;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(#"The amount of items in the table: %u", [[channel items] count]);
return [[channel items] count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView
dequeueReusableCellWithIdentifier:#"UITableViewCell"];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
reuseIdentifier:#"UITableViewCell"];
}
RSSItem *item = [[channel items] objectAtIndex:[indexPath row]];
[[cell textLabel] setText:[item title]];
[[cell detailTextLabel] setText:[item date]];
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 -
// Note we can concatenate literal strings together on multiple lines in this way it
// results in a single NSString instance
NSURL *url = [NSURL URLWithString:
#"http://sephardijews.com/feed/"];
// Putting the URL we made into an NSURLRequest, so we can connect to the url data that we specifed
NSURLRequest *req = [NSURLRequest requestWithURL:url];
// Creating a connecting that will exchange this request for the data from the URL we specifed
connection = [[NSURLConnection alloc] initWithRequest:req
delegate:self
startImmediately:YES];
}
- (void)parser:(NSXMLParser *)parser
didStartElement:(NSString *)elementName
namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qualifedName
attributes:(NSDictionary *)attributeDict
{
NSLog(#"%# found a %# element", self, elementName);
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];
}
}
// 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
{
// Create the parser object with the data received from the web service
NSXMLParser *parser = [[NSXMLParser alloc] initWithData:xmlData];
// Give it a delegate - don't worry about the warning
[parser setDelegate:self];
// Tell it to start parsing - the documet 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;
// Get rid of the connection, no longer need it
connection = nil;
// Reload the table
[[self tableView] reloadData];
NSLog(#"%#\n %#\n %#\n", channel, [channel title], [channel infoString]);
}
- (void)connection:(NSURLConnection *)conn didFailWithError:(NSError *)error
{
// Release the connection object, we are done with it cause' there is no connection
// Setting the connection to nil will stop the connection because it is nothing/0
connection = nil;
// Release the xmlData object. We stopped to connection to put the data in the xmlData object, so we set it to nil also
xmlData = nil;
// Grab the description of the error object passed to us, so we can tell the user
NSString *errorString = [NSString stringWithFormat:#"Fetch failed: %#", [error localizedDescription]];
// Create and show an alert view to the user with the error string to tell them the error in the process of the connection
UIAlertView *av = [[UIAlertView alloc] initWithTitle:#"Error"
message:errorString
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[av show];
}
/* - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
WebViewController *aWebViewController = [[WebViewController alloc] init];
self.webViewController = aWebViewController;
[self.navigationController pushViewController:self.webViewController animated:YES];
RSSItem *entry = [[channel items] objectAtIndex:[indexPath row]];
NSURL *url = [NSURL URLWithString:[entry link]];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
[[webViewController webView] loadRequest:req];
[[webViewController navigationItem] setTitle:[entry title]];
} */
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"showPost"]) {
WebViewController *awebViewController = [segue destinationViewController];
self.webViewController = awebViewController;
NSIndexPath *selectedRow = [self.tableView indexPathForSelectedRow];
RSSItem *entry = [[channel items] objectAtIndex:[selectedRow row]];
NSURL *url = [NSURL URLWithString:[entry link]];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
[[webViewController webView] loadRequest:req];
[[webViewController navigationItem] setTitle:[entry title]];
}
}
#end
Thanks for your help!

Answer 1

Your WebViewController isn't being initialized anywhere. Try this in your tableView:didSelectRowAtIndexPath::
WebViewController *aWebViewController = [WebViewController alloc] init];
self.webViewController = aWebViewController;
[self.navigationController pushViewController:self.webViewController animated:YES];
[aWebViewController release];
If you're using Storyboard, add a view controller and change its class to WebViewController. From the MasterViewController in the Storyboard, right-click on a cell and connect the push segue to the WebViewController. Click the push segue and change its identifier to something like "showPost" or whatever.
Go back to MasterViewController.m and delete your code from tableView:didSelectRowAtIndexPath: and add this:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"showPost"]) {
WebViewController *aWebViewController = [segue destinationViewController];
NSIndexPath *selectedRow = [self.tableView indexPathForSelectedRow];
RSSItem *entry = [[channel items] objectAtIndex:[selectedRow row]];
NSURL *url = [NSURL URLWithString:[entry link]];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
[aWebViewController.webView loadRequest:req];
aWebViewController.title = entry.title
}
}