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POUpdate UILabel from applicationDidBecomeActive?
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copied!<p>I want to update UILabel by clicking a reload button. Additionally, I want to update the label in background, because it is fetching the new data via XML from my website. Of course it would be nice to auto-update the label when the application is opened. And there is my problem:</p> <p>I was able to make it work well when user were clicking the button manually. But I don't understand how to do the same by calling my method via "applicationDidBecomeActive". I tried to do it the same way, but it obviously doesn't work because my label is returned nil.</p> <p>I suppose there is a problem of my understanding and the solution should be quite easy. Thanks for your input! Note: I am a beginner with Objective-C and have sometimes problems with "easy" things. ;-)</p> <p>Below is a summary of the important code parts:</p> <p><strong>AppDelegate</strong></p> <pre><code>- (void)applicationDidBecomeActive:(UIApplication *)application { [[MyViewController alloc] reloadButtonAction]; } </code></pre> <p><strong>MyViewController</strong></p> <pre><code>@synthesize label - (void)reloadButtonAction { [self performSelectorInBackground:@selector(updateData) withObject:nil]; } - (void)updateData { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Parse the XML File and save the data via NSUserDefaults [[XMLParser alloc] parseXMLFileAtURL]; // Update the labels [self performSelectorOnMainThread:@selector(updateLabels) withObject:nil waitUntilDone:NO]; [pool release]; } - (void)updateLabels { NSUserDefaults *variable = [NSUserDefaults standardUserDefaults]; myLabel.text = [variable stringForKey:@"myLabelText"]; // myLabel is nil when calling all of this via AppDelegate // so no changes to the myLabel are done in that case // but: it works perfectly when called via button selector (see below) NSLog(@"%@",myLabel.text); } -(void)viewDidLoad { // Reload button in the center UIButton *reloadButton = [UIButton buttonWithType:UIBarButtonSystemItemRefresh]; reloadButton.frame = CGRectMake(145,75,30,30); [reloadButton setTitle:@"" forState:UIControlStateNormal]; [reloadButton addTarget:self action:@selector(reloadButtonAction) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:reloadButton]; } </code></pre>

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