I'm trying to solve two problems with MKUserTrackingModeFollowWithHeading in iOS 6:
MKUserTrackingModeFollowWithHeading works briefly, but it's jittery and returns to MKUserTrackingModeFollow almost immediately, especially at high zoom levels.
The app occasionally crashes when repeatedly changing the MKUserTrackingMode: I get EXC_BAD_ACCESS on the main thread, without further information. This is hard to reproduce, but it has happened repeatedly.
Any thoughts on what might be causing this? It feels like a bug, but Apple's own "Maps" app doesn't exhibit this behavior.
In order to isolate the problems, I've created a Single View Application with an MKMapView and a UIToolbar (set up in a .xib), to which I'm adding a MKUserTrackingBarButtonItem. The UIViewController acts as a <MKMapViewDelegate>. Here's the complete implementation code:
#import "ViewController.h"
#implementation ViewController
#synthesize mapView, toolbar;
- (void)viewDidLoad
{
[super viewDidLoad];
// Add MKUserTrackingBarButtonItem to toolbar
MKUserTrackingBarButtonItem *trackButton = [[MKUserTrackingBarButtonItem alloc] initWithMapView:self.mapView];
[toolbar setItems:[NSArray arrayWithObjects:trackButton, nil] animated:YES];
}
- (void)mapView:(MKMapView *)mapView didChangeUserTrackingMode:(MKUserTrackingMode)mode animated:(BOOL)animated
{
// Log MKUserTrackingMode change
NSString *modeType = (mode == 0) ? #"None" : ((mode == 1) ? #"Follow" : #"FollowWithHeading");
NSLog(#"MKUserTrackingMode changed to: %#", modeType);
}
#end
This is a bug in MapKit. It can be observed also in Apple Maps using MapKit such as the Find My Friends app. Note that the Apple Maps app is not using MapKit (at least not the same version) thus it's not affected by this bug.
I also do see sporadic EXC_BAD_ACCESS crashes in MapKit. In fact, MapKit related crashes account for the vast majority of my app's crashes. :(
I also noticed that MKUserTrackingModeFollowWithHeading works briefly and it changes to MKUserTrackingModeFollow almost immediately, especially at high zoom levels.
I tried
- (void)mapView:(MKMapView *)mapView didChangeUserTrackingMode:(MKUserTrackingMode)mode animated:(BOOL)animated {
if (mapView.userTrackingMode != MKUserTrackingModeFollowWithHeading) {
[mapView setUserTrackingMode:MKUserTrackingModeFollowWithHeading];
}
}
but this creates a forever loop since right after I change to MKUserTrackingModeFollowWithHeading, something changes back to MKUserTrackingModeFollow. It's really annoying because I don't know what keeps changing the tracking mode to MKUserTrackingModeFollow.
Sorry that my answer was not useful, but I posted here to confirm the problem.
Related
EDIT: It is appearing that there may not be ANY possible way to, on app termination only, set the device volume back to the level it was when an app started. To me this is a possible oversight on the part of Apple. Why wouldn't Apple want my app to be a good camper that leaves their campsite the way they found it, there must be a way, please help... I tried to get an answer to this broader question with another topic but it was closed as a duplicate, please go there and vote to re-open it :)
When my app terminates, I want to set the system volume back to the same volume it was when my app started (Edit: and not change the volume when the app enters the background).
I am attempting to do that with MPVolumeView as the mechanism to set the devices volume. From what I have researched, that seems to be the only way to set the devices volume programmatically. If there is another way, please suggest it.
So, when I launch my app I save the system volume as an external variable 'appStartVol' in my AppDelegate.m.
I let the user change the volume during app usage with MPVolumeView.
Then I try to set the system volume back to the appStartVol in the AppDelegate.m files' applicationWillTerminate. EDIT: applicationWillTerminate is called when a user dismisses apps from their recents list. I do this all the time and leave regularly used apps in recents so I don't have to scroll through 9 pages of icons to find them. So, there is a reason to do what I am asking, in that function.
I use this approach for screen brightness but can not seem to do it for volume.
I am having trouble because I do not seem to be able to get access to my storyboard MPVolumeView in AppDelegate.m applicationWillTerminate and I can not seem to make a local MPVolumeView work in AppDelegate.m applicationWillTerminate.
If I use a UIApplicationWillTerminateNotification notification in my view controller, I still run into the same problems in the notification event since the storyboard MPVolumeView also seems not accessible from that event.
EDIT: This is the reason that using code in applicationDidEnterBackground does not meet my needs: I want my users to be able to use my music player at the volume they have manually chosen in my app even when they decide to bring another app into focus. I believe that this is what the users would naturally assume would happen. For instance, why would the volume change if I want to use the calculator? I also want to believe that the natural assumption for a user would be that the volume should pop back to pre-app volume if the app is dismissed. Using applicationDidEnterBackground would make the app go to pre-app volume both when the app goes into background AND when it terminates, this is not acceptable.
ATTEMPT 1: Here is my code in my AppDelegate.m applicationWillTerminate:
- (void)applicationWillTerminate:(UIApplication *)application {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
NSLog(#"=== App is terminating ===");
UIScreen.mainScreen.brightness = brightnessORG;
NSLog(#"=== Screen brightness back to pre-app level of %f ===", brightnessORG);
UISlider *volumeViewSlider;
for (UIView *view in [_mpVolumeViewParentView subviews]){
if ([view.class.description isEqualToString:#"MPVolumeSlider"]){
volumeViewSlider = (UISlider*)view;
volumeViewSlider.value = appStartVol;
break;
}
}
}
ATTEMPT 1: Here is my AppDelegate.h:
#import <UIKit/UIKit.h>
#import <MediaPlayer/MediaPlayer.h>
extern CGFloat brightnessORG;
extern float appStartVol;
#interface AppDelegate : UIResponder <UIApplicationDelegate>
{
MPVolumeView *_mpVolumeViewParentView;
}
#property (strong, nonatomic) UIWindow *window;
#property (nonatomic, retain) IBOutlet MPVolumeView *mpVolumeViewParentView;
#end
Re. ATTEMPT 1: Although this code runs without error, it does not set the volume back to appStartVol since there are no views in the app delegates [_mpVolumeViewParentView subviews]. I am obviously not accessing the mpVolumeViewParentView that is in my storyboard.
ATTEMPT 2: Lets see if I can just add a local MPVolumeView in AppDelegate.m applicationWillTerminate:
- (void)applicationWillTerminate:(UIApplication *)application {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
NSLog(#"=== App is terminating ===");
UIScreen.mainScreen.brightness = brightnessORG;
NSLog(#"=== Screen brightness back to pre-app level of %f ===", brightnessORG);
MPVolumeView *volumeView = [ [MPVolumeView alloc] init];
UISlider *volumeViewSlider;
volumeViewSlider = (UISlider*)volumeView;
volumeViewSlider.value = appStartVol;
}
Re. ATTEMPT 2: Runs with error = 'Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[MPVolumeView setValue:]: unrecognized selector sent to instance'
But I have tried :), as you can see I am an objective-c newbie...
Any help would be appreciated :)
ATTEMPT 3: Try subviews in local MPVolumeView in applicationWillTerminate:
MPVolumeView *_mpVolumeViewParentView = [ [MPVolumeView alloc] init];
MPVolumeView *volumeView = [ [MPVolumeView alloc] init];
[_mpVolumeViewParentView addSubview:volumeView];
UISlider *volumeViewSlider;
for (UIView *view in [_mpVolumeViewParentView subviews]){
if ([view.class.description isEqualToString:#"MPVolumeSlider"]){
volumeViewSlider = (UISlider*)volumeView;
volumeViewSlider.value = appStartVol;
break;
}
}
Re. ATTEMPT 3: Runs with error at for loop initiation: 'Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[MPVolumeView setValue:]: unrecognized selector sent to instance'
ATTEMPT 4: After adding AVfoundation framework to the project, I added this to my AppDelegate.m:
#import <AVFoundation/AVFoundation.h>
And I put these two lines to AppDelegate.m applicationWillTerminate:
AVAudioPlayer* wavplayer = [[AVAudioPlayer alloc] init];
wavplayer.volume = appStartVol;
Re. ATTEMPT 4: Runs with error at 'wavplayer.volume= appStartVol;': 'Thread 1: EXC_BAD_ACCESS (code=1, address=0x48)' , darn......
First, you are trying something that probably can't work - you are casting MPVolumeView to UISlider and then try to use UISlider's setValue: method. But your object is still MPVolumeView and support that method. So this can't work not because you are using it in wrong place, but in never works.
Also - appWillTerminate is not sufficient, as it's called only in one specific case. If app goes to background first, and then killed - the willTerminate is never called.
I assume you were trying to de something like described here iOS 9: How to change volume programmatically without showing system sound bar popup? - but you should just do the same - so find the UISlider within subviews, instead of casting the whole thing to it.
Edit:
#implementation AppDelegate
{
MPVolumeView* mv;
UISlider* slider;
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
return YES;
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
slider.value = 1;
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
mv = [MPVolumeView new];
for (UIView *view in [mv subviews]){
if ([view.class.description isEqualToString:#"MPVolumeSlider"]){
slider = ((UISlider*)view);
break;
}
}
}
#end
that's the sample code I used. Using in terminate unfortunately didn't work, so that's the most that I see that can be done (I also think it's the more correct way than using terminate, as it's not always called).
Remember this can stop working at any time, or even be rejected when submitted to the AppStore.
I've been writing a simple fahrenheit/celcius converter style app. It works fine in the simulator but when I test the app on my iPhone 4, it is very jerky and slow to update as I move the slider back and forth.
My main view controller looks like this (removed some junk):
#import "MLViewController.h"
#import "MLGradeModel.h"
#import "MLGrade.h"
#interface MLViewController ()
#property (nonatomic, strong) MLGradeModel *gradeModel;
#end
#implementation MLViewController
#synthesize displayLeft = _displayLeft;
#synthesize displayRight = _displayRight;
#synthesize gradeModel = _gradeModel;
#synthesize buttonLeft = _buttonLeft;
#synthesize buttonRight = _buttonRight;
- (IBAction)dragEnter:(UISlider*)sender {
[self sliderUpdate: sender];
}
- (IBAction)sliderInput:(UISlider*)sender {
[self sliderUpdate:sender];
}
- (IBAction) sliderValueChanged:(UISlider *)sender {
[self sliderUpdate:sender];
}
-(IBAction)sliderUpdate:(UISlider*)sender
{
UILabel *myDisplayLeft = self.displayLeft;
UILabel *myDisplayRight = self.displayRight;
float sliderValue = [sender value];
int pos = sliderValue*1000/CONVERSION_SCALE;
NSString *strLeft = [self.gradeModel readGradeFromLeftAtPos:pos];
NSString *strRight = [self.gradeModel readGradeFromRightAtPos:pos];
[myDisplayLeft setText:strLeft];
[myDisplayRight setText:strRight];
// try to redraw, maybe less jerky?
[self.view setNeedsDisplay];
}
-(int) getSliderValue
{
float initialValue = [self.sliderInput value];
return initialValue * 100;
}
- (void)viewDidLoad
{
[super viewDidLoad];
MLGradeModel *model = [MLGradeModel sharedMLGradeModel];
self.GradeModel = model;
}
#end
gradeModel is an NSMutableArray of NSMutableArrays, who contain NSString values. As the slider is dragged, the corresponding position in the arrays should be read. Whose values should then be set to the UILabels.
I thought it should be the most simple thing. Outlets and actions for the UISlider have been dragged in the storyboard.
Edit: Also, when I run the app on the phone, the logs show that the slider input is taken, but the window is not updated at speed "so to say". For example, then I move the slider form left to right the event shows up in the log but the labels are redrawn with 0.5 s delay.
Edit: [self.view setNeedsDisplay]; was added as a test to force a redraw. The program works equally bad/slow when that line is commented away.
Edit: It works equally bad when I change sliderUpdate to:
-(IBAction)sliderUpdate:(UISlider*)sender
{
float sliderValue = [sender value];
int pos = sliderValue*10;
NSString *strFromInt = [NSString stringWithFormat:#"%d",pos];
[self.displayLeft setText:strFromInt];
[self.displayRight setText:strFromInt];
}
-Have I not hooked up all events from the UISlider? I have only set valueChanged to to my viewController's sliderInput (which calls sliderUpdate).
I have this same delay issue with UISlider on an iPhone 4 with my app now i have started targeting iOS 7
On iOS 6 my sliders worked perfectly on an iPhone 4.
The same app works smoothly on a 4s and an ipad mini that i have here
EDIT
What I've just discovered is that in my app there was big difference in the UISlider performance on iPhone 4 under iOS 7 when I built for debug and built for release.
I had a bunch of logging going on in the slider - using DLog instead of NSLog - DLog is a macro that expands to an NSlog on running in debug mode and a no-op in release mode. so it appears that the logging was causing the lagging.
Check to see if you have logging going on in there and either comment them out or, if you are using Dlog, try changing the scheme to release and see if this solves your issue and see if that makes a difference,
To change to release look in Xcode menu Product-Scheme-Edit Scheme)
Made the world of difference to me.
Bit of a relief that !
I've been trying to find some information regarding the new multitasking switcher in iOS 7 and especially the screenshot that the OS takes when the app is going into hibernation.
Is there any way to completely turn off this feature or screenshot? Or can I hide the app altogether from the switcher? The app needs to run in the background, but we do not want to show any screenshot from the app.
The screenshot is potentially a security-risk, think along the lines for banking-apps where your card number or account summary will be available to anyone that double-click on the home button on the device.
Anyone with any insight into this? Thanks.
In Preparing Your UI to Run in the Background, Apple says:
Prepare Your UI for the App Snapshot
At some point after your app enters the background and your delegate method returns, UIKit takes a snapshot of your app’s current user interface. The system displays the resulting image in the app switcher. It also displays the image temporarily when bringing your app back to the foreground.
Your app’s UI must not contain any sensitive user information, such as passwords or credit card numbers. If your interface contains such information, remove it from your views when entering the background. Also, dismiss alerts, temporary interfaces, and system view controllers that obscure your app’s content. The snapshot represents your app’s interface and should be recognizable to users. When your app returns to the foreground, you can restore data and views as appropriate.
See Technical Q&A QA1838: Preventing Sensitive Information From Appearing In The Task Switcher
In addition to obscuring/replacing sensitive information, you might also want to tell iOS 7 to not take the screen snapshot via ignoreSnapshotOnNextApplicationLaunch, whose documentation says:
If you feel that the snapshot cannot correctly reflect your app’s user interface when your app is relaunched, you can call ignoreSnapshotOnNextApplicationLaunch to prevent that snapshot image from being taken.
Having said that, it appears that the screen snapshot is still taken and I have therefore filed a bug report. But you should test further and see if using this setting helps.
If this was an enterprise app, you might also want to look into the appropriate setting of allowScreenShot outlined in the Restrictions Payload section of the Configuration Profile Reference.
Here is an implementation that achieves what I needed. You can present your own UIImageView, or your can use a delegate-protocol pattern to obscure the confidential information:
// SecureDelegate.h
#import <Foundation/Foundation.h>
#protocol SecureDelegate <NSObject>
- (void)hide:(id)object;
- (void)show:(id)object;
#end
I then gave my app delegate a property for that:
#property (weak, nonatomic) id<SecureDelegate> secureDelegate;
My view controller sets it:
- (void)viewDidLoad
{
[super viewDidLoad];
AppDelegate *delegate = [[UIApplication sharedApplication] delegate];
delegate.secureDelegate = self;
}
The view controller obviously implements that protocol:
- (void)hide:(id)object
{
self.passwordLabel.alpha = 0.0;
}
- (void)show:(id)object
{
self.passwordLabel.alpha = 1.0;
}
And, finally, my app delegate avails itself of this protocol and property:
- (void)applicationWillResignActive:(UIApplication *)application
{
[application ignoreSnapshotOnNextApplicationLaunch]; // this doesn't appear to work, whether called here or `didFinishLaunchingWithOptions`, but seems prudent to include it
[self.secureDelegate hide:#"applicationWillResignActive:"]; // you don't need to pass the "object", but it was useful during my testing...
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
[self.secureDelegate show:#"applicationDidBecomeActive:"];
}
Note, I'm using applicationWillResignActive rather than the advised applicationDidEnterBackground, because, as others have pointed out, the latter is not called when double tapping on the home button while the app is running.
I wish I could use notifications to handle all of this, rather than the delegate-protocol pattern, but in my limited testing, the notifications aren't handled in a timely-enough manner, but the above pattern works fine.
This is the solution I worked with for my application:
As Tommy said: You can use the applicationWillResignActive. What I did was making a UIImageView with my SplashImage and add it as subview to my main window-
(void)applicationWillResignActive:(UIApplication *)application
{
imageView = [[UIImageView alloc]initWithFrame:[self.window frame]];
[imageView setImage:[UIImage imageNamed:#"Portrait(768x1024).png"]];
[self.window addSubview:imageView];
}
I used this method instead of applicationDidEnterBackground because applicationDidEnterBackground won't be triggered if you doubletap the home button, and applicationWillResignActive will be. I heard people say though it can be triggered in other cases aswell, so I'm still testing around to see if it gives problem, but none so far! ;)
Here to remove the imageview:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
if(imageView != nil) {
[imageView removeFromSuperview];
imageView = nil;
}
}
Hope this helps!
Sidenote: I tested this on both the simulator and a real device: It Won't Show on the simulator, but it does on a real device!
This quick and easy method will yield a black snapshot above your app's icon in the iOS7 or later app switcher.
First, take your app's key window (typically setup in AppDelegate.m in application:didFinishLaunchingWithOptions), and hide it when your app is about to move into the background:
- (void)applicationWillResignActive:(UIApplication *)application
{
if(isIOS7Or8)
{
self.window.hidden = YES;
}
}
Then, un-hide your app's key window when your app becomes active again:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
if(isIOS7Or8)
{
self.window.hidden = NO;
}
}
At this point, check out the app switcher and verify that you see a black snapshot above your app's icon. I've noticed that if you launch the app switcher immediately after moving your app into the background, there can be a delay of ~5 seconds where you'll see a snapshot of your app (the one you want to hide!), after which it transitions to an all-black snapshot. I'm not sure what's up with the delay; if anyone has any suggestions, please chime in.
If you want a color other than black in the switcher, you could do something like this by adding a subview with any background color you'd like:
- (void)applicationWillResignActive:(UIApplication *)application
{
if(isIOS7Or8)
{
UIView *colorView = [[[UIView alloc] initWithFrame:self.window.frame] autorelease];
colorView.tag = 9999;
colorView.backgroundColor = [UIColor purpleColor];
[self.window addSubview:colorView];
[self.window bringSubviewToFront:colorView];
}
}
Then, remove this color subview when your app becomes active again:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
if(isIOS7Or8)
{
UIView *colorView = [self.window viewWithTag:9999];
[colorView removeFromSuperview];
}
}
I used the following solution:
when application is going to resign I get appWindow snapshot as a View and add blur to it. Then I add this view to app window
how to do this:
in appDelegate just before implementation add line:
static const int kNVSBlurViewTag = 198490;//or wherever number you like
add this methods:
- (void)nvs_blurPresentedView
{
if ([self.window viewWithTag:kNVSBlurViewTag]){
return;
}
[self.window addSubview:[self p_blurView]];
}
- (void)nvs_unblurPresentedView
{
[[self.window viewWithTag:kNVSBlurViewTag] removeFromSuperview];
}
#pragma mark - Private
- (UIView *)p_blurView
{
UIView *snapshot = [self.window snapshotViewAfterScreenUpdates:NO];
UIView *blurView = nil;
if ([UIVisualEffectView class]){
UIVisualEffectView *aView = [[UIVisualEffectView alloc]initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleDark]];
blurView = aView;
blurView.frame = snapshot.bounds;
[snapshot addSubview:aView];
}
else {
UIToolbar *toolBar = [[UIToolbar alloc] initWithFrame:snapshot.bounds];
toolBar.barStyle = UIBarStyleBlackTranslucent;
[snapshot addSubview:toolBar];
}
snapshot.tag = kNVSBlurViewTag;
return snapshot;
}
make your appDelegate implementation be the as follows:
- (void)applicationWillResignActive:(UIApplication *)application {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
//...
//your code
//...
[self nvs_blurPresentedView];
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
//...
//your code
//...
[self nvs_unblurPresentedView];
}
I created Example projects in Swift and Objective C.
Both projects makes the following actions in:
-application:didResignActive - snapshot is created, blurred and added to app window
-application:willBecomeActive blur view is being removed from window.
How to use:
Objecitve C
Add AppDelegate+NVSBlurAppScreen .h and .m files to your project
in your -applicationWillResignActive: method add the following line:
[self nvs_blurPresentedView];
in your -applicationDidEnterBackground: method add the following line:
[self nvs_unblurPresentedView];
Swift
add AppDelegateExtention.swift file to your project
in your applicationWillResignActive function add the following line:
blurPresentedView()
in your applicationDidBecomeActive function add the following line:
unblurPresentedView()
if only use [self.window addSubview:imageView]; in applicationWillResignActive function, This imageView won't cover UIAlertView, UIActionSheet or MFMailComposeViewController...
Best solution is
- (void)applicationWillResignActive:(UIApplication *)application
{
UIWindow *mainWindow = [[[UIApplication sharedApplication] windows] lastObject];
[mainWindow addSubview:imageView];
}
Providing my own solution as an "answers", though this solution is very unreliable. Sometimes i get a black screen as the screenshot, sometimes the XIB and sometimes a screenshot from the app itself. Depending on device and/or if i run this in the simulator.
Please note i cannot provide any code for this solution since it's a lot of app-specific details in there. But this should explain the basic gist of my solution.
In AppDelegate.m under applicationWillResignActive i check if we're
running iOS7, if we do i load a new view which is empty with the
app-logo in the middle. Once applicationDidBecomeActive is called i
re-launch my old views, which will be reset - but that works for the
type of application i'm developing.
You can use activator to configure double clicking of home button to launch multitasking and disable default double clicking of home button and launching of multitasking window. This method can be used to change the screenshots to the application's default image. This is applicable to apps with default passcode protection feature.
Xamarin.iOS
Adapted from https://stackoverflow.com/a/20040270/7561
Instead of just showing a color I wanted to show my launch screen.
public override void DidEnterBackground(UIApplication application)
{
//to add the background image in place of 'active' image
var backgroundImage = new UIImageView();
backgroundImage.Tag = 1234;
backgroundImage.Image = UIImage.FromBundle("Background");
backgroundImage.Frame = this.window.Frame;
this.window.AddSubview(backgroundImage);
this.window.BringSubviewToFront(backgroundImage);
}
public override void WillEnterForeground(UIApplication application)
{
//remove 'background' image
var backgroundView = this.window.ViewWithTag(1234);
if(null != backgroundView)
backgroundView.RemoveFromSuperview();
}
I'm making a split-view based iPad application(Portrait mode only), and I want to know how to recover initial state after viewDidUnload is called.
When split-view application started for the first time,
-splitViewController:willHideViewController:withBarButtonItem:forPopoverController:
is called automatically (right after -viewDidLoad).
I prepares UIBarButtonItems in the method.
If I open modal dialog or something with UIWebViewController (it consumes a lot of memory), application receives memory warning, viewDidUnload(s) are called.
When I close the modal dialog, -viewDidLoad is called automatically, but this time
-splitViewController:willHideViewController:withBarButtonItem:forPopoverController: is not called.
I prepares UIBarButtonItems in
-splitViewController:willHideViewController:withBarButtonItem:forPopoverController:
but it is not called, so buttons are dismissed.
In that case, should I call the method manually?
I found similar posting here.
https://github.com/grgcombs/IntelligentSplitViewController/issues/6
Thanks.
I don't know it is OK to answer to my own question, but maybe I found an answer for this. http://osdir.com/ml/cocoa-dev/2011-02/msg00430.html
It says that we should preserve BarButtonItems in viewDidUnload, and load it in viewDidLoad.
It seems working fine.
- (void)viewDidUnload {
[super viewDidUnload];
self.toolbarItems = self.toolbar.items; // property with retain policy
}
- (void)viewDidLoad {
[super viewDidLoad];
if (self.toolbarItems) {
self.toolbar.items = self.toolbarItems;
self.toolbarItems = nil;
}
}
After calling MKMapView's setCenterCoordinate:animated: method (without animation), I'd like to call selectAnnotation:animated: (with animation) so that the annotation pops out from the newly-centered pushpin.
For now, I simply watch for mapViewDidFinishLoadingMap: and then select the annotation. However, this is problematic. For instance, this method isn't called when there's no need to load additional map data. In those cases, my annotation isn't selected. :(
Very well. I could call this immediately after setting the center coordinate instead. Ahh, but in that case it's possible that there is map data to load (but it hasn't finished loading yet). I'd risk calling it too soon, with the animation becoming spotty at best.
Thus, if I understand correctly, it's not a matter of knowing if my coordinate is visible, since it's possible to stray almost a screenful of distance and have to load new map data. Rather, it's a matter of knowing if new map data needs to be loaded, and then acting accordingly.
Any ideas on how to accomplish this, or how to otherwise (reliably) select an annotation after re-centering the map view on the coordinate where that annotation lives?
Clues appreciated - thanks!
I ran into the same problem, but found what seems like a reliable and reasonable solution:
Implement the delegate method mapView:didAddAnnotationViews:. When I tried selecting the annotation directly within the delegate method, the callout dropped with the pin! That looked odd, so I add a slight delay of a half-second.
-(void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views {
[self performSelector:#selector(selectInitialAnnotation)
withObject:nil afterDelay:0.5];
}
Select the initial annotation as you'd expect, but calling selectAnnotation:animated;
-(void)selectInitialAnnotation {
[self.mapView selectAnnotation:self.initialAnnotation animated:YES];
}
It seems that selectAnnotation:animated: is not called under some conditions. Compare with MKMapView docs:
If the specified annotation is not onscreen, and therefore does not
have an associated annotation view, this method has no effect.
A more consistent way than using a fixed timeout is to listen to the regionDidChange callback. Set the center coordinate of the map to the desired annotation, and when the regionDidChange method is called, then select the annotation in the center, to open the callout.
Here's a little video I took of the thing running randomly between 5 pins.
First, goto the center coordinate of the annotation. Let's say the annotation object is named thePin.
- (void)someMethod {
[map setCenterCoordinate:thePin.coordinate animated:YES];
}
Then in the regionDidChange method, select this annotation.
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated {
[map selectAnnotation:thePin animated:YES];
}
Well just FYI, this is what the docs say,
If the specified annotation is not onscreen, and therefore does not
have an associated annotation view, this method has no effect.
So if I want to call setCenterCoordinate:animated: or setRegion:animated: and then I want to select the annotation by calling, selectAnnotation:animated: , the annotation won't get selected and the callout won't appear beacause of the exact same reason mentioned above in docs, So the way it would be great to have something like, setCenterCoordinate:animated:ComletionBlock but its not there..! The way that worked for me is as below,
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionBeginFromCurrentState|UIViewAnimationOptionCurveEaseInOut animations:^{
[self.mapView setCenterCoordinate:location.coordinate animated:YES];
} completion:^(BOOL finished) {
[self.mapView selectAnnotation:location animated:YES];
}];
This will give you a completion block and u can use that to select the annotation.
What has worked for me was calling selectAnnotation:animated: from the mapView:didAddAnnotationViews: method:
- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views;
{
[mapView selectAnnotation:[[mapView annotations] lastObject] animated:YES];
}
Apple documentation on the same here.
Note that I only had one annotation on the map so [[mapView annotations] lastObject] was fine for my purposes. Your mileage may vary.
I was having a similar problem. I was using the default MKPinAnnotationView with animatesDrop:YES. After I added the annotations to the MKMapView, I was doing this:
[mapView selectAnnotation:[mapView.annotations objectAtIndex:1] animated:YES]
which in the logic of my program, should select the nearest annotation. This wasn't working. I figured out the reason: the annotation view was not on the screen at the time of this select call, because of the pin drop animation. So all I did was set a timer to select the annotation a second later. It's a hack, but it works. I'm not sure if it'll work in every situation though, for instance on a 3G vs. 3Gs. It'd be better to figure out the right callback function to put it in.
selectTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self
selector:#selector(selectClosestAnnotation) userInfo:nil
repeats:NO];
- (void)selectClosestAnnotation {
[mapView selectAnnotation:[mapView.annotations objectAtIndex:1]
animated:YES];
}
I've found several problems with all the solutions I saw for my problem (I want to select a annotation when I added it from viewDidAppear):
Using the mapView:didAddAnnotationViews: delegate method.
This didn't work for me because if the specified annotation is not onscreen, and therefore does not have an associated annotation view, this method has no effect.
Using the mapViewDidFinishLoadingMap: delegate method.
This didn't work for me either because the map is cached now, so the method is called only once, the first time.
Solution:
John Blackburn was very close but without the mapView:didAddAnnotationViews: method. I just call my own selectAnnotation: method, before I add the annotation, with a delay:
[self.mapView addAnnotation:ann];
[self performSelector:#selector(selectAnnotation:) withObject:ann afterDelay:0.5];
And this is what I do in my selectAnnotation: method:
- (void)selectAnnotation:(id < MKAnnotation >)annotation
{
[self.mapView selectAnnotation:annotation animated:YES];
}
Tested on two iPhone 3GS (iOS 5 and 6) and an iPhone 5.
I was having similar difficulty, but was actually not able to make this method work at all, let alone inconsistently.
Here is what I found to work. Maybe it will work for you too:
How to trigger MKAnnotationView's callout view without touching the pin?