Bug 16468 - You_Should_Not_Call_base_In_This_Method exception
Summary: You_Should_Not_Call_base_In_This_Method exception
Alias: None
Product: iOS
Classification: Xamarin
Component: XI runtime ()
Version: 7.0.4.x
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: 7.0.6
Assignee: Bugzilla
Depends on:
Reported: 2013-11-26 16:54 UTC by onureren
Modified: 2013-12-16 12:21 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

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Description onureren 2013-11-26 16:54:43 UTC
UISegmentedControl which is used to switch between the views of a UITabController which is hidden (see the code below). It was working until a few days ago. But now it throws You_Should_Not_Call_base_In_This_Method exception on the line where tabs.selectedIndex is set.

The weird part is, I didn't make any change in this implementation (the only thing I remember is updating the Xamarin version). Besides it still works in simulator but fails on device.

Code sample:

segmentControl.ValueChanged += (sender, e) => { var selectedSegmentId = (sender as UISegmentedControl).SelectedSegment;

                segmentControl.SetImage (UIImage.FromFile ("mapsinglepassive.png"), 0);
                segmentControl.SetImage (UIImage.FromFile ("listsingleactive.png"), 1);
                this.tabs.SelectedIndex = 1;
            }else {
                segmentControl.SetImage (UIImage.FromFile ("mapsingleactive.png"), 0);
                segmentControl.SetImage (UIImage.FromFile ("listsinglepassive.png"), 1);
                this.tabs.SelectedIndex = 0;

Exception detail:

Instance {MonoTouch.Foundation.You_Should_Not_Call_base_In_This_Method: Exception of type 'MonoTouch.Foundation.You_Should_Not_Call_base_In_This_Method' was thrown.
    at MonoTouch.MapKit.MKMapViewDelegate.RegionChanged (MonoTouch.MapKit.MKMapView mapView, Boolean animated) [0x00000] in /Developer/MonoTouch/Source/monotouch/src/MapKit/.pp-MKMapViewDelegate.g.cs:375
    at (wrapper managed-to-native) MonoTouch.ObjCRuntime.Messaging:void_objc_msgSendSuper_int (intptr,intptr,int)
    at MonoTouch.UIKit.UITabBarController.set_SelectedIndex (Int32 value) [0x0002b] in /Developer/MonoTouch/Source/monotouch/src/UIKit/.pp-UITabBarController.g.cs:238
    at PathiApp.HomeViewController+<ViewDidLoad>c__AnonStorey1F.<>m__30 (System.Object sender, System.EventArgs e) [0x00053] in /Users/onureren/Desktop/PathiApp/PathiApp/Screens/HomeViewController.cs:83
    at MonoTouch.UIKit.UIControlEventProxy.Activated () [0x00000] in /Developer/MonoTouch/Source/monotouch/src/UIKit/.pp-UIControl.cs:30
    at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication:UIApplicationMain (int,string[],intptr,intptr)
    at MonoTouch.UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0004c] in /Developer/MonoTouch/Source/monotouch/src/UIKit/.pp-UIApplication.cs:38
    at PathiApp.Application.Main (System.String[] args) [0x00008] in /Users/onureren/Desktop/PathiApp/PathiApp/Main.cs:16 } MonoTouch.Foundation.You_Should_Not_Call_base_In_This_Method
Comment 1 Sebastien Pouliot 2013-11-26 17:16:08 UTC
When you set (change) the `SelectedIndex` of a `UITabController` you're effectively hiding an existing view controller and then showing a new one.

The exception comes from a `MKMapViewDelegate` - so it's likely that the hidden/shown view controller has a `MKMapView`. One that use a delegate where a *required* member is not provided (RegionChanged from the stack trace) an actual implementation.

So this likely comes from a change inside one of the view controllers. The fact that i works on the simulator is (likely) because the MapView region does not change (unless you simulate a different location).

There's not much I can tell you without having the source code.
Comment 2 onureren 2013-11-28 13:41:36 UTC
@Sebastien Pouliot thanks a lot, you are right! the problem is fixed after I add RegionChanged method.
Comment 3 PJ 2013-12-11 18:45:41 UTC
This fix is planned to be released with Xamarin.iOS 7.0.6, which should hit the beta channel before December 23rd.
Comment 4 Mohit Kheterpal 2013-12-16 12:21:55 UTC
As per comment 2, this issue is resolved.
Hence closing this issue.