Posting notifications from the NSNotificationCenter on the certain button click event Hence When I have rapid button events The notification is being called that many times leads to the many problems. I want to cancel the previous posted notification when rapid events happening. How to do with below code.
func buttonClick() {
// I want to cancel the previous Event here
NSNotificationCenter.defaultCenter().postNotificationName("Event", object: self)
}
UPDATE:
Let me explain clearly what I want actually I have one observer method when a button click is happened from that I want to post the some notifications to control some UI elements like changing the button image. The problem is When I hit the button rapidly observer getting called many times as well my notifications being posted on the same count hence UI is blinking I can't have control on the Observer on the button click event I have only control over the posted event from my side.
Any help much appreciated.
NSNotificationCenter.post() is synchronous. It does not return until all the observers have performed their actions. So there is no way to cancel it; there is no queue.
If you are generating a lot of notifications very close to each other (especially within the same run-loop cycle), you can coalesce them using NSNotificationQueue with enqueueNotification. Generally something like:
NSNotificationQueue.defaultQueue().enqueNotification(note, postingStyle: .whenIdle)
That said, if this is tied to a button click (a human interaction), then the notifications are likely very far apart in computer terms. Half a second is an eternity in computer terms. If that's the case, you're likely better-off controlling this first at the UI, by disabling the button until you're willing to accept another click (for example with button.enabled = false).
It is possible to write a wrapper that coalesces operations over any arbitrary period, but this is likely to be confusing in your case, because the user will be able to click something that the system will ignore. If that's still what you want, I'll see if I can find an example of a coalescing trampoline (I've written them in ObjC, but I don't have a Swift example on hand).
Related
First of all I'd like to say sorry in case my question is dummy, I'm really new to iOS and what to understand how thing are going on. Imagine such a situation - user taps on home button and the app starts to collapse, but immediately after taping on home button user taped on some UI element. So, I'm wondering how the iOS will handle this? I tried to do some tests using breakpoints, but since it just test I can't be 100% sure. It seems that if the UI interaction event will happen before the system will call willResignActive then the event will be fully processed and if the system will call willResignActive first, then the even will be discarded and won't be handled at all. Is this correct, or I missed something? Thanks
First, why do you want to use this in your app? If a user presses a button exactly in this time, it's okay that the action is not handled.
The only thing you have to keep track of is that whenever the button gets pressed and let's say you store a file without a completion handler it could be that you present an alert which is saying that everything went well but you actually not saved the file because the user left the app in this time.
But since you're never doing critical actions without completion handlers, in my opinion, there's no need to make sure that this doesn't happen.
If I got you wrong, just comment!
This is my first post here on stackoverflow so forgive me for anything I'm doing wrong.
I'm making a kind of guide to the users without any computer knowledge of my application where I show him how to use it by signalizing what he should do, more specifically where to click. I want to that by moving a "fake" cursor to the button and simulate a click, and here is where I got my problem, I have to simulate just the animation of the click, and not the event itself but I couldn't find a way to do that, can anyone help me?
What you're describing is exactly what WH_JOURNALPLAYBACK is for. It populates the message queue with the mouse and keyboard messages you want to occur, and the OS interprets them. In your case, activate the playback hook and perform the mouse events necessary for performing a click.
In preparation, you'll probably want to use WH_JOURNALRECORD to discover what messages you need. Once you have them, you can probably winnow them down to a reasonably sized list prior to shipping your product to customers. (In particualr, you'll probably record many more mouse-move messages than you really need.)
In your button's click handler, check whether playback is active. Only perform the rest of the event handler when playback isn't active. That way, your program will behave just as though the button were clicked (including any animation), but it won't execute the real event code.
Is it possible to record set of touch events on iPhone and then playback?
I have searched alot but could not find any answer. if its possible, can anyone explain with an example.
I m not looking for testing purpose. Within my application, instead of creating animation, i just want to record set of events and then want to playback to explain the app flow to the users.
Regards.
Recording is pretty simple. Look at the various "Responding to Touch Events" and "Responding to Motion Events" methods on UIResponder. Just create your own UIView subclass (since UIView inherits from UIResponder) and keep a copy of the events passed into the relevant methods.
Playback is a bit more complicated; there's no way to make UITouch or UIEvent objects (so you can't make a fake event and pass it on to -[UIApplication sendEvent:]). But, there's nothing stopping you from manually parsing an array of Event objects and handling it on your own (aside from it being some kind of ugly code).
There's no built-in macro capability, but you could certainly build that ability into your application. You'll need to do more than just play back events, though. Touches aren't normally visible, but if you're trying to explain how to use your app to the user you'll probably want to have some sort of visual representation for the touches that trigger different responses similar to the way the iOS Simulator uses white dots to represent multiple touches when you hold down the option key.
Assuming that you can solve that problem, two strategies for easily recording user actions come to mind:
Use the Undo Manager: NSUndoManager is already set up to "record" undoable events. If you invest some time into making everything in your app undoable, you could (maybe) perform a set of actions, undo them all to move them to the redo stack, and then save the events in the redo stack as your script.
Use Accessibility: The Accessibility framework sends notifications whenever user interface elements are touched. Your app could use those notifications to create a playback script. You'll still need to write the code to play back the events in the script, though.
You could mirror your application with AirServer and use any screen capture software to make the video.
I have a state-transition problem with NSTimer, of which I find difficult to keep track of during applicationWillResignActive / applicationDidEnterBackground, according to the context of my app.
I was wondering if it might not be a better idea to utilise UILocalNotification, especially given it's background/inactive firing. However, I wanted to know whether we have the ability to provide a custom method to UILocalNotification, of which does not present a dialog box (would damage the whole point of my app). In effect, i'd like to only make use of the timer-fire capabilities of UILocalNotification, and handle the fire event with my own method which does something very "undialog-friendly"
Have checked the ADC docs and it alludes to the dialog being presented every time.
Any advice you can give on this would be appreciated.
thanks
sc.
The dialog box is presented when your app is in the background. But it is not presented when your app is running - instead your app is free to deal with the notification however it sees fit. So it would be perfectly possible to hook it up to a custom method of your own making.
The main reason for this behaviour is a user may not want to go into your app if it's in the background. Of course, with iOS 5 the notification may not be a dialog box - it could be one of the new notification styles.
I am developing a tic tac toe game for iOS and I am using a combination of UIButtons and UIImageViews to allow for user interaction and to display the moves made. My problem is that the buttons continue to accept user input before the cpu makes it's move, which breaks my game logic. I have made several attempts to toggle the userInteractionEnabled property, but I have only been able to turn it off. The engine that gets everything started in the game is my buttonPressed method. I also toggle the userInteractionEnabled property within this method and therein lies my problem: How do I re-enable the property after disabling user interaction? Is there a method that is called in between events that I can overwrite?
I have searched the web and I have searched through the developer documentation provided by Apple and I found information on the touchesBegan and touchesEnded methods. However, from what I understand, those methods need to be explicitly called which brings me back to my original problem of not being able to call those functions without the user's interaction.
If anyone can help, I would greatly appreciate it! I have been racking my brain over this for the past couple of weeks and I am just not seeing a solution.
I'd think that for a game like tic-tac-toe, calculating the countermove should be so fast that it can be done immediately in response to the first button press. If you're doing something complicated to calculate the next move, like kicking off a thread, you might want to reconsider that.
Let's say, though, that your game is something like chess or go, where coming up with a countermove might take a bit longer. Your view controller should have a method to make a move for the current player, let's call it -makeMove:. Your -buttonPressed action should call that method to make a move for the user. In response, -makeMove: should update the state of the game, switch the current player to the next player. If the new current player is the computer, it should then disable the controls and start the process of calculating the next move. Let's imagine that's done by invoking some NSOperation, so that coming up with the next move is an asynchronous task. Once the operation has come up with a move, it should again invoke -makeMove: (by calling -performSelectorOnMainThread:), which will again update the game state and the current player. This time, though, it should see that the new current player is not the computer, and so it should re-enable the controls.