I'd like to make a continuous loop to get information from iTunes to get stuff like: the player position (1:37), current track being played, etc... I'm using iTunes.h and ScriptingBridge to get the iTunes Data.
I have tried using [NSTimer scheduledTimerWithTimeInterval:0 target:self selector:#selector(getInformation) userInfo:nil repeats:YES]; but from what I've seen on the Activity Monitor this consumes a lot of the CPU and if, for example, I press a button inside the NSWindow where I have the NSTimer, the UI of my App, that supposedly was going to be updated, is not updated. If I let go of the button the UI starts updating normally.
I have also tried using a while(1){} but for some reason my App freezes.
Does any1 have any idea on how to perform what I'm looking for?
that'll burn CPU like crazy.. dont poll!
sign up for the distributed notification:
//the distributed notification sent
#define SONG_CHANGE_NOTIFICATION #"com.apple.iTunes.playerInfo"
shameless advertisment: look at source of DDBoomBox on github which does EXACTLY what you wanna do :)
https://github.com/Daij-Djan/BoomBox
Related
I am using the bellow code but timer kill in background. but i want to keep running my nstimer in background-
NSTimeInterval time = 5;
self.locationUpdateTimer =
[NSTimer scheduledTimerWithTimeInterval:time
target:self
selector:#selector(updateLocation1)
userInfo:nil
repeats:NO];
You can get location events while the app is in the background, and here is Apple documentation that explains how to do that. And you probably also want to use something called "the Significant-Change Location Service".
And when the change happens, you'll get a call on your CoreLocation method "location manager: didUpdateLocations:". Sample code can be seen in the "Significant-Change Location Service" section.
Doing the above will be a lot easier to do than to try to implement a timer that runs while your application is in the background (and probably fully suspended, as many apps tend to be).
And if you didn't get a location update, that means your phone didn't move. :-)
I'm trying to figure out a way to have a timer that begins at the time that an app is installed and continues to run even when the app is in the background. I'm basically using the timer to periodically check the battery life of an external device that is linked to the phone. I've been told that the best way to do this is to use some sort of delegate calls to a timer function, but I'm fairly new to IOS and am pretty confused on how to do that. I know how to set up the timer and get the battery life, I'm however perplexed on how to keep the timer going through the life of the app. Any help you could give would be extreeemely appreciated! Thanks a bunch!
Running an app in the background (forever) isn't possible.
But while your app is running... you can set the repeats parameter of the method scheduledTimerWithInterval:target:selector:userInfo:repeats: to YES.
Here's a link to running it in the background for a certain period of time to perform a relatively large task.
run even when the app is in the background
Not possible. You can request an extra 10 minutes, but thats it. You will not be able to write your app as is.
For the timer part of your question, you can do this:
[NSTimer scheduledTimerWithTimeInterval:60.0
target:self
selector:#selector(checkBattery:)
userInfo:nil
repeats:YES];
But you should really be subscribing to the notifications on battery change events. Here is sample code from apple that shows how to do it.
coneybeare is right. This is iOS policy, which is in place exactly to prevent what you are trying to do, i.e. exhaust the iPhone's (or iPad's) battery life.
I have a problem with an app where I implemented an NSOperationQueue.
It seems that pressing the close button of the iPad makes the UI freeze. The app itself is still running in the background, the UI is updated, it's just that it won't answer to touches or rotation anymore and it doesn't get closed as it should be.
I have an update module that downloads quite a long list of xml files and saves them on the device. The operation queue has a MaxConcurentOperations value of 2.
Usually everything works fine, the app runs fine and dandy, responding to my touches and rotation UNTIL I press the device's button. After this, the UI simply freezes. The progress is still updated (an UILabel), recurrent animations are still displayed, but the app is not closed until all the operations are done.
I'm not calling waitUntilAllOperationsAreFinished on my queue so I don't know what might be causing this.. So far, I've only made tests on a first generation iPad, with iOs 5.0
If anyone can provide me with some tips, I'll really appreciate it. If necessary, I can post the NSOperationQueue and NSOperation class codes, but somehow I have the feeling this about me approaching this wrongly, and not about a faulty line of code
[edit]
I also use a timer to periodically check on the download status, but I noticed that not calling the timer doesn't eliminate the problem
self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:#selector(xmlDownloaded) userInfo:nil repeats:YES];
[edit2]
After some further research, I made sure that my operations are concurrent and just to be sure, I changed the way I added my operations to the queue.
Instead of
[downloadQueue addOperation:op];
I added them to a mutable array called "operations" and in the end I used
[downloadQueue addOperations:operations waitUntilFinished:NO];
but my app still freezes when I press the close button...
Wild guess, you are locking the main thread waiting for your operation to complete / you are destroying your operation delegate on viewWillDisappear?
It seems there was another function causing this, even though I don't understand why...
I had a label animation
CABasicAnimation *fadey = [CABasicAnimation animationWithKeyPath:#"opacity"];
[fadey setToValue:[NSNumber numberWithFloat:0.35f]];
fadey.repeatCount = HUGE_VALF;
[fadey setAutoreverses:YES];
[fadey setDuration:0.6f];
This small function was causing the app to wait until all the operations were finished in order to close the app. The weird part is that the function was not even called in with the NSOperations, but before them
Again, I have no idea why... everything breaks when I press the close button, otherwise there are no problem. So if anyone else runs into a similar issue, it might help to check for some repeating animations
I'm trying to figure out a way to give a user feedback when they have saved settings. similar to Microsoft's "File Saved" dialog Is there a class for this type of dialog? I do not want to require any action by the user. Just "Your setting have been saved" then disappears after a short delay. Maybe a better way to describe would be like a jQuery message box with a fade in fade out type thing
Is there a class for this type of dialog?
That isn't a "dialog", because you're not accepting input from the user. At best, it's an alert, and you could therefore use NSAlert (see also "Dialogs and Special Panels") however, what you are contemplating is contrary to the recommendations given in the HIG for "Alerts":
Avoid using an alert merely to give users information. Although it’s important to tell users about serious problems, such as the potential for data loss, users don’t appreciate being interrupted by alerts that are informative but not actionable. Instead of displaying an alert that merely informs, give users the information in another way, such as in an altered status indicator.
In other words, this probably wouldn't be considered a good user experience by the OS X-using population.
You can still do this, if you absolutely must, by creating a sheet or alert window and setting a timer to dismiss it.
A much better plan would be to have a label somewhere in your interface whose text could display this information, again using a timer to clear the notice after an appropriate duration.
Yet another option (possibly the best) would be to put this notice somewhere that the user only sees it upon request. The HIG mentions Mail.app's information area at the bottom of its sidebar, for example.
It is simple to fade a window in and out using the NSViewAnimation see also NSAnimation Class
An example I use something like this.
- (void)fadeWindowIn{
//--make sure the window starts from 0 alpha. Or you may get it jumping in view then try and fade in.
[theWindow setAlphaValue:0.0];
//-- set up the dictionary for the animation options
NSDictionary *dictIn = [NSDictionary dictionaryWithObjectsAndKeys:
theWindow,NSViewAnimationTargetKey,
NSViewAnimationFadeInEffect,NSViewAnimationEffectKey,nil];
NSViewAnimation * fadeWindowIntAnim = [[[NSViewAnimation alloc] initWithViewAnimations:[NSArray arrayWithObject:dictIn]] autorelease];
[fadeWindowIntAnim setAnimationCurve:NSAnimationLinear];
[fadeWindowIntAnim setDuration:2];
[fadeWindowIntAnim setFrameRate:20.0];
//--start the animation
[fadeWindowIntAnim startAnimation];
//--set the timer for the fade out animation
[NSTimer scheduledTimerWithTimeInterval:4.8 target:self selector:#selector(fadeWindowOut) userInfo:nil repeats:NO];
}
-(void)fadeWindowOut{
//-- fade the window.
NSDictionary *dictOut = [NSDictionary dictionaryWithObjectsAndKeys:
theWindow,NSViewAnimationTargetKey,
NSViewAnimationFadeOutEffect,NSViewAnimationEffectKey,nil];
NSViewAnimation * fadeOutAnim = [[[NSViewAnimation alloc] initWithViewAnimations:[NSArray arrayWithObject:dictOut]] autorelease];
[fadeOutAnim setAnimationCurve:NSAnimationLinear];
[fadeOutAnim setDuration:1.2];
[fadeOutAnim setFrameRate:20.0];
[fadeOutAnim startAnimation];
}
theWindow is the NSWindow or NSView you want to fade in and out. Read the references to understand the options.
You can create your own such popup (using NSTimer to dismiss as needed), but perhaps an easier way would be to use the existing third-party library at http://code.google.com/p/toast-notifications-ios/. This library emulates Android's "toast" functionality.
Note that this library is for iOS development (not OSX), but wasn't sure which platform you were planning to target. Regardless, it should be adaptable with a little work.
The other answers about timers and such cover that aspect of it pretty well. I just wanted to jump in and suggest you take a look at the Growl framework. This seems to be the preferred way to do this sort of passive notification until Apple builds it into the OS.
Among other things, it gives the user a lot of control over how the notifications look, where they live on the screen, how long they stay up, and which apps are even allowed to display them. And they do this without you having to write any code. The downside is that it's another thing for your users to have to install, which could be a deal breaker for your app.
They also recently moved into the App Store and started charging a nominal fee ($2 or $3, I think) which could be seen as a downside but I think of it as a more positive thing: users will have a much easier time installing it now.
Some apps that make use of Growl notifications include BBEdit, Transmission, Scrivener, Twitteriffic, etc. Which is to say that it's not a fly-by-night thing.
As a user, I hate it when apps try to roll their own notifications since I lose all of the control that I get with Growl.
Just a thought, anyway.
For some reason when I push down (click and hold) on any control, the NSTimer in my App freezes and does not fire until I release the mouse button. It simply does not fire while I have the mouse pressed. This is fine for short periods, but it also freezes if I have a popup menu open, or a combobox dropped down.
I'm not sure if there is something I missed, but it seems like this is incorrect behavior.
I want to be able to click the down arrow of an NSPopUpButtonCell (or even click and hold an NSTableView) without the entire NSTimer freezing (which redraws an NSView).
Any comments / suggestions would be appreciated.
The NSTimer is added to the currentRunLoop with mode NSDefaultRunLoopMode.
While the mouse is down, the run loop is in the NSEventTrackingRunLoopMode. Therefore, any event that's not received onto the EventTracking event queue won't be serviced until the runloop returns to the appropriate mode.
The way around this is to add the timer to the runloop for both modes (default and event tracking).
Instead of adding two or more timers to different runloops or using multithreading (as you won't then be able to update the UI from another thread) simply add the timer to the NSRunLoopCommonModes:
NSTimer *myTimer = [NSTimer timerWithTimeInterval:RefreshInterval target:self selector:#selector(doWork) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:myTimer forMode:NSRunLoopCommonModes];
Assuming you're just dealing with one thread in your application, what you described is perfectly expected. By default, NSTimer's are added to the current NSRunLoop which, in your case, is also responsible for dealing with UI interaction. When it gets tied up with handling UI interaction, it can't check your timer and "fire" it.
A solution is to use multi-threading so as to avoid this tie-up. Here's a nice blog post on this very subject: http://blog.narent.com/?p=21
EDIT: See Dave's post for an alternative (and more elegant IMO) solution
Also see:
NSTimer doc
NSRunLoop doc
Threading programming guide