iOS crash with Xamarin Forms 4.0

[jijithvasudevan]

Has anyone faced this issue?

System.NullReferenceException with iOS for Calendar when used with Xamarin forms 4.0 Crash is here : Control.SetTitle(element.TextWithoutMeasure, UIControlState.Normal)

Stack Trace at XamForms.Controls.iOS.CalendarButtonRenderer.OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00040] in /Users/jijithvasudevan/Downloads/XamForms.Controls.Calendar-master/XamForms.Controls.Calendar.iOS/CalendarButtonRenderer.cs:27 at (wrapper delegate-invoke) .invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs) at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:211 at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:353 at Xamarin.Forms.BindableObject.ClearValue (Xamarin.Forms.BindableProperty property, System.Boolean fromStyle, System.Boolean checkAccess) [0x000c6] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:78 at Xamarin.Forms.BindableObject.ClearValue (Xamarin.Forms.BindableProperty property) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:30 at Xamarin.Forms.Platform.iOS.VisualElementRenderer1[TElement].Dispose (System.Boolean disposing) [0x0007d] in <db147fad2aa9412c845ff0ead92dfe20>:0 at Xamarin.Forms.Platform.iOS.ViewRenderer2[TView,TNativeView].Dispose (System.Boolean disposing) [0x0005c] in :0 at Xamarin.Forms.Platform.iOS.ButtonRenderer.Dispose (System.Boolean disposing) [0x00064] in :0 at Foundation.NSObject.Dispose () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/Foundation/NSObject2.cs:147 at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose (System.Boolean disposing) [0x0003f] in :0 at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose () [0x00000] in :0 at Xamarin.Forms.Platform.iOS.VisualElementRenderer1[TElement].Dispose (System.Boolean disposing) [0x00058] in <db147fad2aa9412c845ff0ead92dfe20>:0 at Foundation.NSObject.Dispose () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/Foundation/NSObject2.cs:147 at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose (System.Boolean disposing) [0x0003f] in <db147fad2aa9412c845ff0ead92dfe20>:0 at Xamarin.Forms.Platform.iOS.VisualElementPackager.Dispose () [0x00000] in <db147fad2aa9412c845ff0ead92dfe20>:0 at Xamarin.Forms.Platform.iOS.VisualElementRenderer1[TElement].Dispose (System.Boolean disposing) [0x00058] in :0 at Foundation.NSObject.Dispose () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/Foundation/NSObject2.cs:147 at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildRemoved (Xamarin.Forms.VisualElement view) [0x0003e] in :0 at Xamarin.Forms.Platform.iOS.VisualElementPackager.OnChildRemoved (System.Object sender, Xamarin.Forms.ElementEventArgs e) [0x0000f] in :0 at Xamarin.Forms.Element.OnChildRemoved (Xamarin.Forms.Element child) [0x00007] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:337 at Xamarin.Forms.VisualElement.OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\VisualElement.cs:750 at Xamarin.Forms.Layout.OnInternalRemoved (Xamarin.Forms.View view) [0x00012] in D:\a\1\s\Xamarin.Forms.Core\Layout.cs:464 at Xamarin.Forms.Layout.InternalChildrenOnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x0002b] in D:\a\1\s\Xamarin.Forms.Core\Layout.cs:427 at System.Collections.ObjectModel.ObservableCollection1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e) [0x00018] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/external/corefx/src/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs:263 at System.Collections.ObjectModel.ObservableCollection1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedAction action, System.Object item, System.Int32 index) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/external/corefx/src/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs:338 at System.Collections.ObjectModel.ObservableCollection1[T].RemoveItem (System.Int32 index) [0x00021] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/external/corefx/src/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs:182 at System.Collections.ObjectModel.Collection1[T].RemoveAt (System.Int32 index) [0x0002b] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/external/corefx/src/Common/src/CoreLib/System/Collections/ObjectModel/Collection.cs:146 at Xamarin.Forms.TemplateUtilities.OnContentChanged (Xamarin.Forms.BindableObject bindable, System.Object oldValue, System.Object newValue) [0x00018] in D:\a\1\s\Xamarin.Forms.Core\TemplateUtilities.cs:63 at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00120] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:445 at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x00173] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:379 at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x00042] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:316 at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:293 at Xamarin.Forms.ContentView.set_Content (Xamarin.Forms.View value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\ContentView.cs:11 at XamForms.Controls.Calendar+<>c__DisplayClass89_0.b__0 () [0x00029] in /Users/jijithvasudevan/Downloads/XamForms.Controls.Calendar-master/XamForms.Controls.Calendar/Calendar.cs:513 at Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/Foundation/NSAction.cs:152 --- End of stack trace from previous location where exception was thrown ---

at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr) at UIKit.UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) [0x00005] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/UIKit/UIApplication.cs:79 at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0002c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/UIKit/UIApplication.cs:63 at CalendarDemo.iOS.Application.Main (System.String[] args) [0x00001] in /Users/jijithvasudevan/Downloads/XamForms.Controls.Calendar-master/Example/CalendarDemo/CalendarDemo.iOS/Main.cs:17

[jijithv]

Fixed in nuget package JV.XamForms.Controls.Calendar

[mrtn]

Thanks for the fix. Had the same issue.

[rhodesie123]

Yeah all that's needed to fix this issue is to check to see if the Control attribute is null in the OnElementPropertyChanged function in the CaeldnarButtonRender. So this:

protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            var element = Element as CalendarButton;
            if (Control != null)
            {
                if (e.PropertyName == nameof(element.TextWithoutMeasure) || e.PropertyName == "Renderer")
                {
                    Control.SetTitle(element.TextWithoutMeasure, UIControlState.Normal);
                    Control.SetTitle(element.TextWithoutMeasure, UIControlState.Disabled);
                }
                if (e.PropertyName == nameof(element.TextColor) || e.PropertyName == "Renderer")
                {
                    Control.SetTitleColor(element.TextColor.ToUIColor(), UIControlState.Disabled);
                    Control.SetTitleColor(element.TextColor.ToUIColor(), UIControlState.Normal);
                }
                if (e.PropertyName == nameof(element.BackgroundPattern))
                {
                    DrawBackgroundPattern();
                }
                if (e.PropertyName == nameof(element.BackgroundImage))
                {
                    DrawBackgroundImage();
                }
            }
        }

[lubiepomaranczki]

It's also fixed in XamForms.Enhanced.Calendar ver. 1.2.1 which is a fork of this repository but updated. If it doesn't work, please raise an issue here

Good luck! 🚀