Just came across a bug in MapKit, wanted to see what the community is experiencing. When adding a MKUserTrackingBarButtonItem to a UIToolBar, I'm seeing the map is not releasing from memory when switching to another viewController (though I see the dealloc is firing).
Can anyone confirm they are seeing this behavior? My testing shows the map releases properly if I do not add MKUserTrackingBarButtonItem. Using iOS7, testing with Instruments/Leaks.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
MKUserTrackingBarButtonItem *userTrackingBarButtonItem = [[MKUserTrackingBarButtonItem alloc] initWithMapView:self.mapView];
[userTrackingBarButtonItem setAction:#selector(track:)];
UIBarButtonItem *flexibleSpaceBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
[self setToolbarItems:[NSArray arrayWithObjects:flexibleSpaceBarButton, userTrackingBarButtonItem, flexibleSpaceBarButton, nil] animated:YES];
[self.navigationController setToolbarHidden:NO animated:NO];
}
MKUserTrackingBarButtonItem and the MKMapView each hold strong references to each other, resulting in a circular retain. This appears to be a bug in MapKit itself, and it's still present in iOS 7.1.
A solution is to add a dealloc to your view controller that contains the MapView:
-(void)dealloc
{
userTrackingBarButtonItem.mapView = nil; // Circular reference bug workaround
}
Related
Is there a callback offered by UIWebView that is called when scrolling occurs, and if so, how can I get the current content offset?
Thanks.
You can using this property available in ios 5.0:
#property(nonatomic, readonly, retain) UIScrollView *scrollView
Or prior to iOS 5.0:
NSArray *subViews = [NSArray arrayWithArray:[myWebview subviews]];
UIScrollView *webScroller = (UIScrollView *)[subViews objectAtIndex:0];
You can then implement the UIScrollViewProtocol and do something like this:
UIScrollView *webScrollView = myWebView.scrollView;
webScrollView.delegate = self;
//implement method from delegate..
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
//Scrolled
}
To get the contentOffset all you have to do is:
CGPoint offSet = webScrollView.contentOffset;
I have tried hiding a segmented controller just like a button or label can be hidden in XCode. It's intended to be hidden/shown when touching a parent segmented controller above. This Code would work with Buttons or Labels:
mySegmContr.hidden = YES;
But it just won't work for segmented controllers. Can you help me out?
I figured out that you can use a simple UIView in which you put the things you want to hide. The UIView can then be hidden with
myView.hidden = YES;
still I found no way to hide a segmented control directly.
If you create a property for the segment controller you can do more stuff with it like changing it's location, resizing it and want you want hiding it.
In your .h file do this
UISegmentedControl *mySegment;
#property (nonatomic, retain) UISegmentedControl *mySegment;
-(void) createMySegment;
In your .m file do this
#synthesize mySegment;
- (void) createMySegment {
if ([self mySegment] == nil) {
NSArray *buttons = [NSArray arrayWithObjects:#"One", #"Two", #"Three", nil];
UISegmentedControl *segName = [[UISegmentedControl alloc] buttons];
[self setMySegment:segName];
[segName release];
segName.frame = CGRectMake(110, 62, 120, 25);
segName.segmentedControlStyle = UISegmentedControlStyleBar;
segName.momentary = NO;
segName.selectedSegmentIndex = 0;
[segName addTarget:self
action:#selector(pickMethod:)
forControlEvents:UIControlEventValueChanged];
[self.view addSubview:segName];
}
}
NOTE: With "setMySegment" above make sure you use a capital first letter which is M in "mySegment".
Then when you want to hide it use this. Don't for get to dealloc mySegment.
[[self mySegment] setHidden:YES];
This is the follow up to my question earlier about the Xcode 4 static analyzer. It is not specifically a problem since I have the code now working as it needs to, but I am just wondering how things are working behind the scenes. Consider the following code:
- (IBAction)cameraButtonPressed:(id)sender
{
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] == NO)
{
return;
}
UIImagePickerController *cameraUI = [[UIImagePickerController alloc] init];
cameraUI.sourceType = UIImagePickerControllerSourceTypeCamera;
cameraUI.allowsEditing = NO;
cameraUI.delegate = self;
[self presentModalViewController:cameraUI animated:YES];
NSString *theString = [[NSString alloc] initWithString:#"cameraButtonPressed done"];
NSLog(#"%#", theString);
}
To me, the way this code looks, there are two objects (cameraUI and theString) that need to be released. However, the analyze function correctly identifies that only theString needs to be released at the end of the method, even though both objects are returned from alloc-init, which in my experience has always meant that you release when you are done.
The question I have here is, how does the static code analyzer know not to flag cameraUI as an issue?
I would call this a bug with the static analyzer. The UIImagePickerController instance assigned to cameraUI should be released or autoreleased in a non-garbage-collected environment (like iOS).
I have created navigation based project. and in second screen i want to add uitabbarcontroller. so can any one suggest how i do this.
i already did lot of search but no success yet. so please can you provide a simple sample of this. i already tried below discussion but i think its not a good approach.
Navigation Based Application with TabBar
Thanks
Actually this is the correct approach. The one thing that is not correct is where the controllers are allocated. This is happened in the previous controller, the one that is making the push, but should be allocated in the object that is responsible, the TabBarController.
When you implement your action to show the UITabBarController make the following code:
- (void) theAction {
SomeTabBarControllerSubClass *controller = [[SomeTabBarControllerSubClass alloc] init];
[self.navigationController pushViewController:controller animated:YES];
[controller release];
}
Then when you implement the SomeTabBarControllerSubClass class:
(.h)
#interface SomeTabBarControllerSubClass : UITabBarController {
UIViewController *first;
UIViewController *second;
}
#end
(.m)
#implementation SomeTabBarControllerSubClass
- (void) viewDidLoad {
first = [[UIViewController alloc] init]; //Or initWithNib:
second = [[UIViewController alloc] init];
first.view.backgroundColor = [UIColor greenColor] //Just example
second.view.backgroundColor = [UIColor redColor] //Just example
first.tabBarItem.image = [UIImage imageNamed:#"someImage.png"];
self.viewControllers = [NSArray arrayWithObjects:first,second,nil];
}
- (void) dealloc {
[first dealloc];
[second dealloc];
[super dealloc];
}
#end
I have the following problem making me crazy.
My app has to play a tick sound every second for a specified number of times (e.g. 5) after the user has pressed a button.
I used this:
for (int w=1; w<=5; w++) {
[NSThread detachNewThreadSelector:#selector(tic) toTarget:self withObject:nil];
[NSThread sleepForTimeInterval:1.0];
}
where:
- (void)tic {
NSAutoreleasePool *ticPool = [[NSAutoreleasePool alloc] init];
player_tic = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath: [[NSBundle mainBundle] pathForResource:#"tick" ofType:#"aif"]] error:nil];
[player_tic setDelegate:self];
[player_tic play];
[ticPool drain];
}
and:
- (void) audioPlayerDidFinishPlaying: (AVAudioPlayer *)player_tic successfully:(BOOL)flag {
NSLog(#"Audio finished playing.");
[player_tic release];
}
All seems to work. My problem is that the object are released together at the end.
I need that after every played sound the related 'player_tic' has to be released immediately.
Other Info:
In .m:
#synthesize player_tic;
In .h:
#interface myController : UIViewController {
...
AVAudioPlayer *player_tic;
}
#property (nonatomic, retain) AVAudioPlayer *player_tic;
On top of all, I have this warning in compilation:
local declaration of 'player_tic' hides instance variable
Please help me!
Thank you very much in advance.
--Carlo
I found System Sound Services more responsive than AVAudioPlayer.
It also solves your release problem, which is caused by the retain property of your controller. Read the reference manual on memory management for further information on retain/release.
I think you want to use self.player_tic when setting that variable, and i believe you also want to autorelease that instance. I'm not sure that setting up a separate NSAutoreleasePool is necessary either.
self.player_tic = [[[AVAudioPlayer alloc] initWithContentsOfURL:... error:nil] autorelease]