How to detect the hour changing in ios? - ios

Question

I want to do something like this in my iOS app. Let's say user open the app now. then I want to show a view. during that 1st hour, no matter how manytimes he open the app I need to show the 1st view through out this hour. when start a new hour I want to show the view 2. again after the 3rd hour I need to show that first view.
Like wise
1hr - view 1
2hr - view 2
3hr - view 1
4hr - view 2
How can I monitor this hours changing from my ios app even its not runing in the background
Thank you

Answer 1

If the app isn't running in the background, you really can't monitor the hour changing. But that doesn't matter since you can't show a view when the app is not running.
When the app is running, just use NSTimer and set it to repeat at the right time to tell your controller that the hour is changing. Let the controller deal with figuring out which view to show.
This is important, because you have to make the decision of which view to show even when the hour isn't changing. For example, when you first open the app.
See NSTimer

Answer 2

AppDelegate.m
- (void)applicationDidEnterBackground:(UIApplication *)application {
NSUserDefaults *standardDefaults = [NSUserDefaults standardUserDefaults];
[standardDefaults setObject:[NSDate date] forKey:#"kTimeInterval"];
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
[[NSNotificationCenter defaultCenter] postNotificationName:kNotificationNameForBecameActive object:nil userInfo:#{kUserInfoForBecameActive: self.currentTime}];
}
ViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(didBecomeActive:) name:kNotificationNameForBecameActive object:nil];
}
- (void)didBecomeActive:(NSNotification *)notification {
NSUserDefaults *standardDefaults = [NSUserDefaults standardUserDefaults];
NSDate *previousDate = [standardDefaults objectForKey:#"kTimeInterval"];
NSTimeInterval secondsPassed = [[NSDate date] timeIntervalSinceDate:previousDate];
if (secondsPassed >= CHECK_SWAP_VIEW) {
// Change your view here.
}
}
Here you can do like save time when application goes in background or quit. Then whenever application will open check for previous time and then swap your views.