Calling navigation controller method from background operation - iphone

Question

I'm running a background operation using NSOperation, which gets kicked off from my AppDelegate. What I want to do is when the operation is complete, have it call a method in the RootViewController.m file.
Currently there's a property in my AppDelegate named navigationController, and I"ve been trying to set up the call like this:
AppDelegate.m:
GetRSSOperation *gro = [[GetRSSOperation alloc] initWithURL:rssURL target:self selector:#selector(dataSourceDidFinishLoadingNewData:)];
[queue addOperation:gro];
[gro release];
GetRSSOperation.m:
[target performSelectorOnMainThread:selector withObject:alerts waitUntilDone:YES];
I have tried setting the target to self, self.navigationController, self.navigationController.view but none work.
I am aware that the issue might be due to my not yet having a complete understanding of the entire ios architecture, so would appreciate any pointers please.
**Adding more code to explain:
AppDelegate.h
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#interface AppDelegate : NSObject {
NSOperationQueue *queue;
UIWindow *window;
UINavigationController *navigationController;
NSURL *rssURL;
// storage for the alert list from RSS feed
NSMutableArray *alerts;
}
#property (nonatomic, retain) IBOutlet UIWindow *window;
#property (nonatomic, retain) IBOutlet UINavigationController *navigationController;
#property (nonatomic, retain) NSMutableArray *alerts;
#property (nonatomic, retain) NSURL *rssURL;
#property (retain) NSOperationQueue *queue;
+ (id)shared;
#end
AppDelegate.m
#import "AppDelegate.h"
#import "RootViewController.h"
#import "AlertViewController.h"
#import "RefreshTableHeader.h"
#import "GetRSSOperation.h"
#implementation AppDelegate
static AppDelegate *shared;
#synthesize window, navigationController, alerts;
- (id)init
{
if (shared) {
[self autorelease];
return shared;
}
if (![super init]) return nil;
queue = [[NSOperationQueue alloc] init];
shared = self;
return self;
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Add the navigation controller's view to the window and display.
UIImageView *imageview=[[UIImageView alloc]initWithFrame:CGRectMake(270, 3, 37, 37)];
imageview.image=[UIImage imageNamed:#"iphone.png"];
[self.navigationController.navigationBar addSubview:imageview];
[self.window addSubview:navigationController.view];
[self.window makeKeyAndVisible];
if (rssURL == nil) {
NSString *alertAddress = #"http://www.compoundstockearnings.com/com/public/selections.cfc?method=getrss&email=";
alertAddress = [alertAddress stringByAppendingString:cseLogin];
alertAddress = [alertAddress stringByAppendingString:#"&password="];
alertAddress = [alertAddress stringByAppendingString:csePass];
rssURL = [[NSURL alloc] initWithString:alertAddress];
}
GetRSSOperation *gro = [[GetRSSOperation alloc] initWithURL:rssURL target:self selector:#selector(dataSourceDidFinishLoadingNewData:)];
[queue addOperation:gro];
[gro release];
return YES;
}
return NO;
}
#end
GetRSSOperation just does the rss call, puts it in memory then tries to call the main navigation controller:
[target performSelectorOnMainThread:selector withObject:alerts waitUntilDone:YES];
The main navigation controller upon which I wish the thing to execute a selector, looks like this:
RootViewController.h
#import <UIKit/UIKit.h>
#interface RootViewController : UITableViewController {
IBOutlet RefreshTableHeader *alertTable;
UIImageView *imageView;
}
#end
RootViewController.m:
#import "RootViewController.h"
#import "AppDelegate.h"
#implementation RootViewController
- (void)dataSourceDidFinishLoadingNewData:(NSMutableArray *)tempAlerts
{
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
appDelegate.alerts = tempAlerts;
reloading = NO;
[alertTable flipImageAnimated:NO];
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:.3];
[self.tableView setContentInset:UIEdgeInsetsMake(0.0f, 0.0f, 0.0f, 0.0f)];
[alertTable setStatus:kPullToReloadStatus];
[alertTable toggleActivityView:NO];
[UIView commitAnimations];
[popSound play];
}
Obviously I've shortened it a bit but that's the core of it. I just want the GetRSSOperation to be able to call RootViewController.m - dataSourceDidFinishLoadingNewData. any input appreciated.

Answer 1

It sounds like you're having a bit of trouble figuring out just how to format the call to performSelectorOnMainThread:withObject:waitUntilDone: correctly. It's pretty simple, really.
If you would normally call the method like this:
[target method:alerts]
you format the performSelector call like this:
[target performSelectorOnMainThread:#selector(method:) withObject:alerts waitUntilDone:YES];