I am not dumb and I know how to reload data. I am in a tricky situation where I have a UIView inside another UIView both named OHGridView. I have to keep them named the same way.
With the OHGridView example code, the refresh looked a little like this:
[(OHGridView *)self.view reloadData];
But now that I added a UIView, it no longer works.
Any help is appreciated!
Edit:
Code removed
The NSNotificationCenter may be what you need. You can register for events (eg a perform update event) and then post these events from anywhere. These go to the notification center and then to your class/view. When the event is received, you just do what is needed.
The docs are here:
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSNotificationCenter_Class/Reference/Reference.html
Inside the OHGridView you would call during initialization:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(ReloadNotification:) name:#"ReloadOHGridView" object:nil];
Then, just define the method:
- (void)ReloadNotification:(NSNotification *)notification
{
[self reloadData];
}
So, when you want an update to occur, you then just call:
[[NSNotificationCenter defaultCenter] postNotificationName:#"ReloadOHGridView" object:self];
When you deallocate the OHGridView you should remove the observer:
[[NSNotificationCenter defaultCenter] removeObserver:self];
Related
I have these lines of code:
-(void)someMethod:(UIScrollView*)scrollView{
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(keyboardWasShown:)
name:UIKeyboardDidShowNotification object:nil];
}
-(void)keyboardWasShown:(NSNotification *)aNotification{
// I want to get scrollView over here
}
Is there a way to make this possible? I've tried to perform this staff according to
How to pass a NSDictionary with postNotificationName:object:
but aNotification.userInfo doesn't contain my data
[[NSNotificationCenter defaultCenter]
postNotificationName:UIKeyboardDidShowNotification
object:self
userInfo:#{#"scrollView":scrollView}];
You are listening to UIKeyboardDidShowNotification and then you post UIKeyboardWillHideNotification that won't work. First maybe you like create your own notification name i.e XYZKeyboardDidShowNotification and then register for that and post using that name with the additional data you want. And then you can do:
-(void)keyboardWasShown:(NSNotification *)aNotification{
UIScrollView *scrollView = aNotification.userInfo[#"scrollView"];
}
I have a method in a view controller that sets up some notifications:
- (void)processState
{
MYGame *game = [[MYGameManager sharedInstance] getGameAtIndex:self.indexPath.row];
if(game)
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(notification_gameUpdated:) name:kMYNotificationGameUpdated object:game];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(notification_gameEnded:) name:kMYNotificationGameEnded object:game];
}
}
Then there's a game updated method, which is called every so often:
- (void)notification_gameUpdated:(NSNotification *)notification
{
MYGame *game = notification.object;
_game_status = (game.entity.bet.isWinning) ? MYGameStatusWin : MYGameStatusLose;
}
And finally, when the game ends:
- (void)notification_gameEnded:(NSNotification *)notification
{
MYGame *game = notification.object;
// Clear the notifications
[[NSNotificationCenter defaultCenter] removeObserver:self name:kMYNotificationGameUpdated object:game];
[[NSNotificationCenter defaultCenter] removeObserver:self name:kMYNotificationGameEnded object:game];
self.gameIsActive = NO;
}
Trouble is, that even when I remove the observers (and a breakpoint shows that this is happening), then the notification_gameUpdated: method is still being called. If I change it to
[[NSNotificationCenter defaultCenter] removeObserver:self name:kMYNotificationGameUpdated object:nil];
This still won't clear it. But if I change it to
[[NSNotificationCenter defaultCenter] removeObserver:self name:nil object:game];
Then that does clear it. As does
[[NSNotificationCenter defaultCenter] removeObserver:self];
But I'm not keen on doing either, because I'd rather the code was clean and I don't want any "gotchas" further down the line if I need to add more observers. I've checked the rest of the code and cannot find any other classes adding observers to this object, although other view controllers do listen to the same messages.
Is processState called more than once? That would explain the behavior you are seeing.
If it is, one way to fix the issue would be to always remove listeners before adding them. See e.g. this answer.
edit #2
try registering with object:nil and when you post the notification include the reference to game in the userInfo dictionary. then, in the receiver, you can compare against game and perform whatever action you want if it is a match. this should get you the same behavior as if you were using object:game, although it does not explain why your current implementation isn't working
when you register for notifications like this:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(notification_gameUpdated:)
name:kMYNotificationGameUpdated
object:game];
the #selector will only be performed if that particular instance of game is the sender.
is it possible that you're re-initializing your shared instance of game after registering? that could cause the behavior you're experiencing
try registering for notifications with object:nil and see what happens. (assuming there are not multiple games running concurrently)
So it turned out that the reason for the issue was Method Swizzling. The project I'm working on has addObserver:selector:name:object: and removeObserver:name:object: swizzled. The issue was that although addObserver has been handled correctly, removeObserver is only removing objects on specific conditions. This will obviously need to be changed...
But I post this as a warning to others... Swizzling can be dangerous to your health!
Apologies for any time wasted.
I would like to save some data from an array into a plist file when the applicationDidEnterBackground is called. I'm trying to figure it out how to access my array from the applicationDidEnterBackground method. Is there any best practice to do this?
Many thanks
Marcos
Put the code in the class that actually has the data. Have the class register for the UIApplicationDidEnterBackgroundNotification notification.
// Put this in the `init` method
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(backgrounding) name:UIApplicationDidEnterBackgroundNotification object:nil];
// The method that gets called
- (void)backgrounding {
// save the data
}
// Put this in the `dealloc` method
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
With this setup you don't have to get anything into the UIApplicationDelegate and the responsibility is kept where it belongs.
what is method call when change size in Window?
I find somesing aboud windowDidResize: so i try doing
- (void)windowDidResize:(NSNotification *)notification {
NSLog(#"test");
}
I found what need use NSWindowDidResizeNotification, but I work for the first time with NSNotification and bad understand about this.
Can somebody write a full example for my event, please?
The -windowDidResize: method is called on the window delegate. Is the object with the method you posted the delegate for the window?
For something other than the delegate, you can do:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(windowDidResize:) name:NSWindowDidResizeNotification object:theWindow];
and, when the observer is no longer interested or being deallocated:
[[NSNotificationCenter defaultCenter] removeObserver:self name:NSWindowDidResizeNotification object:theWindow];
Another approach is to use the new block-based API to NSNotificationCenter:
id observation = [[NSNotificationCenter defaultCenter] addObserverForName:NSWindowDidResizeNotification object:theWindow queue:nil usingBlock:^(NSNotification *){
NSLog(#"test");
}];
// store/retain the observation for as long as you're interested in it. When it's deallocated, you stop observing.
You can Implement NSWindowDelegate:
class YourVC: NSWindowDelegate {
// This method trigger when you press the resize button in the window toolbar
func windowDidResize(_ notification: Notification) {
// Write your code here
}
}
And, In viewDidLoad() or viewDidAppear() method
self.view.window?.delegate = self
You can also use other delegate methods:
windowDidEnterFullScreen
windowDidExitFullScreen
...
I have an iOS 5 ARC-based project, and am having difficulty about where I should be removing the observer for the NSNotificationCenter observations which I have registered within a UIViewController. Similar posts on SO have said this should be done in the -dealloc method. Even though this method is not required in ARC projects I have added it with the following code:
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
As a test, I open the UIViewController (within a UINavigationController), do some things which trigger the notifications, and then pop it off the stack by tapping the Back button. I then reopen the UIViewController, and do some more things to trigger the notifications, but notice that each callback is being called twice - an indication that the previous notifications have not been deregistered. Repeating this procedure just causes each callback to be called more than more times, so they appear to never be deregistering.
Any help would be appreciated!
It's pretty clear your dealloc method isn't being called (nor is the removeObserver call).
Why not remove your UIViewController's observer in the viewDidUnload: or viewWillDisappear: methods?
If your dealloc isn't being called, it's likely because someone is still holding a reference to the view controller. Perhaps you need to mark something as __weak? You can use the allocations instrument to help track down what's holding on to your view controller.
"I also need the notification callbacks to still be fired if the view is off-screen" -> you may need to register UIApplicationWillEnterForegroundNotification. If so, let try this:
- (void)viewWillAppear:(BOOL)animated {
NSLog(#"viewWillAppear");
[super viewWillAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(applicationDidEnterBackground:)
name:UIApplicationDidEnterBackgroundNotification
object:nil];
}
- (void)viewWillDisappear:(BOOL)animated {
NSLog(#"viewWillDisappear");
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
NSLog(#"applicationWillEnterForeground");
[[NSNotificationCenter defaultCenter] removeObserver:self];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(applicationDidEnterBackground:)
name:UIApplicationDidEnterBackgroundNotification
object:nil];
// do your stuff here
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
NSLog(#"applicationDidEnterBackground");
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(applicationWillEnterForeground:)
name:UIApplicationWillEnterForegroundNotification
object:nil];
}
The idea is adding or removing UIApplicationDidEnterBackgroundNotification whenever coming in and out of your screen. We just register UIApplicationWillEnterForegroundNotification when the app enter background and remove once it's back. Be noticed that we just remove UIApplicationDidEnterBackgroundNotification when viewWillDisappear.
My dealloc() is not called by somehow, so I found this way, hope it useful for you too.
Enjoy :)