nsnotificationcenter

问题 I have a simple viewController that I want to listen for UIKeyboardWillHideNotification . Therefore I have the following code: - (void) viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillBeHidden) name:UIKeyboardWillHideNotification object:nil]; } - (void) keyboardWillBeHidden { [self.scrollView setContentOffset:CGPointMake(0, 0) animated:YES]; } I'm trying to decide when to remove the

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: iOS application: how to clear notifications? is there a way how to remove notification from notification center(iOS 5) when I click it and start my application ? Thanks a lot 回答1: Set the applicationIconBadgeNumber property of your UIApplication instance to 0. That is, [UIApplication sharedApplication].applicationIconBadgeNumber = 0; Edit: In the current iOS SDK, you can't remove just a single notification from

问题 This question already has answers here : Send and receive messages through NSNotificationCenter in Objective-C? (6 answers) Closed 6 years ago . I saw a few examples about adding observer and handle in the same class, but what I want to know is if it's possible to add observer in first view controller and handle it in second view controller? I want constantly send distance from first view controller and handle it in the 2nd one. The 2nd view controller added as a sub view: addSubview ,

问题 I want to move the content of the bottom of my UIViewController upwards as the keypad appears. At the bottom of the view controller I have a UITextField and when the user clicks it the keypad appears and blocks i,t so the user cannot see what they are inputting into the UITextField. I have the UITextField declared as follows: @IBOutlet var startTime : UITextField Would I need a UIScrollView to accomplish this? or is there a way to move the content of the page upwards as the keypad appears.

问题 I'd like to retrieve a list of observers (objects and selectors) for a given notification name. I know there's no official API for that. I also know I could subclass NSNotificationCenter to accomplish this. Sometimes however this is not a viable option because NSNotificationCenter usage is spread all over the code or even binary frameworks. So I'm looking for an unofficial/private way to do this. (Since it's about debugging only, that's fine.) 回答1: Finally, Apple added a way to print all

问题 Is there a way to broadcast data from one widget to other widgets? Similar to a BroadcastReceiver on Android or NSNotificationCenter on iOS. Specifically, I'm trying to detect when a Navigator pops or pushes a new view. I added navigatorObservers to MaterialApp. And when a widget comes back to the foreground, I want to be able to notify it by broadcasting changes from didPush and didPop with the actual route that's in the current foreground 回答1: Navigator.push returns a Future that will

问题 I am able to observe the CNContactStoreDidChangeNotification when the contact database is changed while the app is in background state. I am pretty sure that only one observer was added to NSNotificationCenter . The problem is NSNotificationCenter posts MULTIPLE times (2, 3, 5, and even more times) even if I only add one new contact. Where is the problem? 回答1: Make certain you aren't adding the observer multiple times. This can happen without you realizing it if (for example) you call

问题 My iphone app is pretty simple with one view that handles everything, in viewDidLoad I check to see if we have an internet connection and if we do we load from the web and if not we load from a local resource. And this works fine. //in viewDidOnload [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleNetworkChange:) name:kReachabilityChangedNotification object:nil]; reachability = [Reachability reachabilityForInternetConnection]; [reachability startNotifier];

问题 A UIViewController adds itself to the default center: [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(editFood) name:@"editFood" object:nil]; Then a UITableView delegate NSObject posts a NSNotification : [[NSNotificationCenter defaultCenter] postNotificationName:@"editFood" object:self]; During run time it get a EXC_BAD_ACCESS exception. Is the defaultCenter getting released somewhere? The same concept works when I post a notification to a UIViewController from a

问题 NOTE: Asking for answers in Swift please. What I'm trying to do: Have tableview cells update every 1 second and display a real-time countdown. How I'm doing it currently: I have a tableview with cells that contain a label. When the cells are generated, they call a function that calculates the time between today and a stored target date, and it displays the countdown time remaining in the label. To get the cells to update the label every second, I use an NSTimer that reloads the tableview