displaying splash screen while downloading images from server in ios - ios

Question

in my app i am trying to make a slider using the LWSlideShow LWSlideShow
the source of images are fetched from my server after trying the solution here i stuck with error that said unbalanced call and it means that i am presenting a modal view on a view that did not completed his animation after solving this problem by putting animation to no the splashView that i present will be dismissed before the images are downloaded here is my code for further explanation:
- (IBAction)goDownload {
UIViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:#"Splash"];
[self.navigationController presentViewController:vc animated:YES completion:nil];
dispatch_async(dispatch_get_main_queue(), ^{
NSMutableArray *array = [#[] mutableCopy];
LWSlideItem *item = [LWSlideItem itemWithCaption:#""
imageUrl:#"http://code-bee.net/geeks/images/cover-1.jpg"];
[array addObject:item];
item = [LWSlideItem itemWithCaption:#""
imageUrl:#"http://code-bee.net/geeks/images/cover-2.jpg"];
[array addObject:item];
item = [LWSlideItem itemWithCaption:#""
imageUrl:#"http://code-bee.net/geeks/images/cover-3.jpg"];
[array addObject:item];
LWSlideShow *slideShow = [[LWSlideShow alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.view.bounds), 120)];
slideShow.autoresizingMask = UIViewAutoresizingFlexibleWidth;
//slideShow.delegate = self;
[self.view addSubview:slideShow];
slideShow.slideItems = array;
if ([slideShow.slideItems count] == [array count]) {
[self dismissViewControllerAnimated:YES completion:nil];
}
});
}
//
//-(void)viewWillAppear:(BOOL)animated
//{
//
// UIViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:#"Splash"];
// [self.navigationController presentViewController:vc animated:YES completion:nil];
//}
- (void)viewDidLoad {
[super viewDidLoad];
[self goDownload];
}
also you can see from the code that also i try to use viewWillAppear same thing happened what i want is when the images are downloaded the splashView need to be dismissed i dont know what i am doing wrong

Answer 1

Running that code from a VC anytime before viewDidAppear (like viewDidLoad, viewWillAppear) will cause the problem you describe. But you probably don't want the slide show view to appear - even for an instant - until you're done fetching the assets. This is a common problem.
The solution is to realize that the "splash screen" and the network tasks aren't just preamble, they are as much a part of your application as the slide show.
EDIT
Make that Splash vc the app's initial view controller in storyboard. Right now, the slide show vc probably looks like this:
Uncheck the "Is Initial View Controller" checkbox, find your splash view controller (in the same storyboard, I hope) and check it's box to be the initial view controller. Now your app will start up on the splash vc, like you want it.
When the splash vc done, it can present the slide show vc, or it can even replace itself (with the slide show ) as the app window's root.
To replace the UI, I use variations of this snippet...
// in the splash vc, after all of the asset loading is complete
// give what used to be your initial view controller a storyboard id
// like #"MySlideShowUI"
UIViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:#"MySlideShowUI"];
UIWindow *window = [UIApplication sharedApplication].delegate.window;
window.rootViewController = vc;
[UIView transitionWithView:window
duration:0.3
options:UIViewAnimationOptionTransitionCrossDissolve
animations:nil
completion:nil];