UIAlertView showing up only after it's dismissed - objective-c

Question

I've been trying to figure this out for 2 days now, and before anyone posts another stackoverflow question, I've read them all and none of them cover my problem exactly:
I have a CoreData app that updates dynamically. Now during the update I want an UIAlertView to pop up saying that an update is being downloaded.
So here's the important code:
AppDelegate:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
[myUpdater checkForUpdatesInContext:self.managedObjectContext];
}
_
Updater Class:
- (void)checkForUpdatesInContext:(NSManagedObjectContext *)myManagedObjectContext
{
[self loadUpdateTime];
NSLog(#"Update start");
NSDate *now = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone localTimeZone] secondsFromGMT]];
if ([now timeIntervalSinceDate:updateTime] < UPDATE_TIME_INTERVAL)
{
return;
}
[self showAlertViewWithTitle:#"Update"];
... //updating process
[self.alertView dismissWithClickedButtonIndex:0 animated:YES];
NSLog (#"Update done");
}
- (void) showAlertViewWithTitle:(NSString *)title
{
self.alertView = [[UIAlertView alloc] initWithTitle:title message:#"Daten werden aktualisiert..." delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
... //design the alertView
[self.alertView show];
NSLog (#"AlertView shows");
}
So here is what happens when I run this:
Launch image shows
NSLog "Update starts" fires
NSLog "AlertView shows" fires
Screen dims but no AlertView is shown
Update is running
NSLog "Update done" fires
Launch image goes away and TabBarController shows up
UIAlertView shows up and is dismissed right away and the dimmed screen returns to normal
What I would like to have happen:
Launch image
TabBarController shows up
Screen dims and UIAlertView shows
Update is running
UIAlertView gets dismissed and dimmed screen returns to normal
I know it's something with the UI Thread and the main Thread and stuff.. But I tried every combination it seems but still not the expected result. Please help :)
EDIT:
HighlightsViewController Class:
- (void)viewDidLoad
{
[super viewDidLoad];
self.updater = [[Updater alloc] init];
[updater checkForUpdatesInContext:self.managedObjectContext];
... // other setup stuff nothing worth mentioning
}
Is this the right place to call [super viewDidLoad]? Because it still doesn't work like this, still the update is being done while the Launch Image is showing on the screen. :-(( I'm about to give this one up..

Answer 1

Here you go, in this prototype things work exactly how you want them to.
Header:
#import <UIKit/UIKit.h>
#interface AlertViewProtoViewController : UIViewController
{
}
- (void) showAlertViewWithTitle:(NSString *)title;
- (void) checkForUpdatesInContext;
- (void) update;
- (void)someMethod;
- (void)someOtherMethod;
#end
#import "AlertViewProtoViewController.h"
Class:
#implementation AlertViewProtoViewController
UIAlertView *alertView;
bool updateDone;
UILabel *test;
bool timershizzle;
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor yellowColor];
UILabel *test = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 500, 500)];
test.backgroundColor = [UIColor blueColor];
[self.view addSubview:test];
[self performSelector:#selector(checkForUpdatesInContext) withObject:nil afterDelay:0.0];
}
- (void)update
{
//NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; //commented for auto ref counting
NSLog(#"update start");
//your update stuff
NSLog(#"update end");
updateDone = YES;
//[pool release];
}
- (void)checkForUpdatesInContext//:(NSManagedObjectContext *)myManagedObjectContext
{
//[self loadUpdateTime];
NSLog(#"Update start");
NSDate *now = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone localTimeZone] secondsFromGMT]];
// if ([now timeIntervalSinceDate:updateTime] < UPDATE_TIME_INTERVAL)
// {
// return;
// }
[self showAlertViewWithTitle:#"Update"];
//[self setManagedObjectContext:myManagedObjectContext];
[self performSelector:#selector(someMethod) withObject:nil afterDelay:0.0];
[self performSelector:#selector(someOtherMethod) withObject:nil afterDelay:0.0];
}
-(void)someOtherMethod
{
while (!updateDone) {
// NSLog(#"waiting...");
}
[alertView dismissWithClickedButtonIndex:0 animated:YES];
NSLog (#"Update done");
self.view.backgroundColor = [UIColor greenColor];
}
-(void)someMethod
{
[self performSelectorInBackground:#selector(update) withObject:nil];
}
- (void) showAlertViewWithTitle:(NSString *)title
{
alertView = [[UIAlertView alloc] initWithTitle:title message:#"Daten werden aktualisiert..." delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
alertView.frame = CGRectMake(100, 100, 200, 200);
alertView.backgroundColor = [UIColor whiteColor];
[self.view addSubview:alertView];
[self.view setNeedsDisplay];
NSLog (#"AlertView shows");
}
#end
You should adjust were needed for your own purposes but it works.

Answer 2

You are starting a background thread and then dismissing the alert immediately. I would suggest that you might use an NSNotification, posted from the background task, and received in whichever controller starts the alert, triggering a method that dismissed the alert.
I find the UIAlertView interface unsuitable for this type of user notice, and prefer to use a semi-transparent overlay view with a UIActivityIndicatorView, plus an informing message for the user.

Answer 3

You are doing a:
- (void)applicationDidBecomeActive:(UIApplication *)application
Isn't it so that the alertview you want to show needs a view to be loaded which isn't active yet at this point? See: http://developer.apple.com/library/ios/#documentation/uikit/reference/UIAlertView_Class/UIAlertView/UIAlertView.html
Similar question? UIAlertView starts to show, screen dims, but it doesn't pop up until it's too late!