iOS 8.3 UIAlertController crashes when trying to a

Question

I have an iPad app. I am creating an UIAlertController and adding a textfield. It crashes. It only crashes when I add a textfield.

let alert = UIAlertController(title: "Enter Name", message:nil, preferredStyle: UIAlertControllerStyle.Alert);         
alert.addTextFieldWithConfigurationHandler { (textfield:UITextField!) -> Void in
                textfield.placeholder = "Sexy time";

            }
 alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: {(action:UIAlertAction!) -> Void in
      //Some action here   
 }));

 self.presentViewController(alert, animated: true, completion: nil);

I get a fun crash telling me that the constraints are messed up. This code works fine in < 8.3 with no warnings. Even on a clean project with nothing in it but this code, it crashes - The project needs to be a splitview project on iPad.

Here is the full stack trace plus bizarre constraint warnings which appears only after trying to add the textfield to alertController.

2015-04-10 15:25:07.155 Observation[18235:281813] The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x7fb66cf9dfc0 UITableView:0x7fb66b855000.left == UIView:0x7fb66fae68e0.left>
    When added to a view, the constraint's items must be descendants of that view (or the view itself). This will crash if the constraint needs to be resolved before the view hierarchy is assembled. Break on -[UIView _viewHierarchyUnpreparedForConstraint:] to debug.
2015-04-10 15:25:07.155 Observation[18235:281813] The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x7fb66cf9e010 UITableView:0x7fb66b855000.right == UIView:0x7fb66fae68e0.right>
    When added to a view, the constraint's items must be descendants of that view (or the view itself). This will crash if the constraint needs to be resolved before the view hierarchy is assembled. Break on -[UIView _viewHierarchyUnpreparedForConstraint:] to debug.
2015-04-10 15:25:07.155 Observation[18235:281813] The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x7fb66fb37f90 UITableView:0x7fb66b855000.top == UIView:0x7fb66fae68e0.top>
    When added to a view, the constraint's items must be descendants of that view (or the view itself). This will crash if the constraint needs to be resolved before the view hierarchy is assembled. Break on -[UIView _viewHierarchyUnpreparedForConstraint:] to debug.
2015-04-10 15:25:07.156 Observation[18235:281813] The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x7fb66fb80580 UITableView:0x7fb66b855000.bottom == UIView:0x7fb66fae68e0.bottom>
    When added to a view, the constraint's items must be descendants of that view (or the view itself). This will crash if the constraint needs to be resolved before the view hierarchy is assembled. Break on -[UIView _viewHierarchyUnpreparedForConstraint:] to debug.
2015-04-10 15:25:13.589 Observation[18235:281813] View hierarchy unprepared for constraint.
    Constraint: <NSLayoutConstraint:0x7fb66cf9dfc0 UITableView:0x7fb66b855000.left == UIView:0x7fb66fae68e0.left>
    Container hierarchy: 
<UIView: 0x7fb66fa86e00; frame = (0 0; 0 0); layer = <CALayer: 0x7fb66fadf8e0>>
   | <UIView: 0x7fb66af3e080; frame = (0 0; 0 0); clipsToBounds = YES; layer = <CALayer: 0x7fb66fae32c0>>
   |    | <_UIAlertControllerShadowedScrollView: 0x7fb66fa68c80; frame = (0 0; 0 0); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x7fb66fa38a80>; layer = <CALayer: 0x7fb66fa97560>; contentOffset: {0, 0}; contentSize: {0, 0}>
   |    |    | <UIView: 0x7fb66fa87350; frame = (0 0; 0 0); layer = <CALayer: 0x7fb66fadf810>>
   |    |    |    | <UILabel: 0x7fb66fa88740; frame = (0 0; 0 0); text = 'Enter Name'; userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7fb66fa94ed0>>
   |    |    |    | <UILabel: 0x7fb66fa73710; frame = (0 0; 0 0); userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7fb66cc0ee10>>
   |    |    |    | <UIView: 0x7fb66fae68e0; frame = (0 0; 0 0); clipsToBounds = YES; layer = <CALayer: 0x7fb66fa90160>>
   |    | <UILabel: 0x7fb66fa3ad40; frame = (0 0; 0 0); userInteractionEnabled = NO; layer = <_UILabelLayer: 0x7fb66fa73680>>
   |    | <UICollectionView: 0x7fb66c130200; frame = (0 0; 0 0); clipsToBounds = YES; gestureRecognizers = <NSArray: 0x7fb66faebab0>; layer = <CALayer: 0x7fb66fa3acf0>; contentOffset: {0, 0}; contentSize: {0, 0}> collection view layout: <_UIAlertControllerCollectionViewFlowLayout: 0x7fb66fae0b30>
    View not found in container hierarchy: <UITableView: 0x7fb66b855000; frame = (0 20; 768 1004); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x7fb66cf79f30>; layer = <CALayer: 0x7fb66cf600a0>; contentOffset: {0, 0}; contentSize: {768, 25}>
    That view's superview: NO SUPERVIEW
2015-04-10 15:25:13.594 Observation[18235:281813] *** Terminating app due to uncaught exception 'NSGenericException', reason: 'Unable to install constraint on view.  Does the constraint reference something from outside the subtree of the view?  That's illegal. constraint:<NSLayoutConstraint:0x7fb66cf9dfc0 UITableView:0x7fb66b855000.left == UIView:0x7fb66fae68e0.left> view:<UIView: 0x7fb66fa86e00; frame = (0 0; 0 0); layer = <CALayer: 0x7fb66fadf8e0>>'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000102940c65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010221dbb7 objc_exception_throw + 45
    2   CoreFoundation                      0x0000000102940b9d +[NSException raise:format:] + 205
    3   Foundation                          0x0000000101daf479 -[NSLayoutConstraint _addToEngine:integralizationAdjustment:mutuallyExclusiveConstraints:] + 187
    4   UIKit                               0x00000001039bca34 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke_2 + 474
    5   Foundation                          0x0000000101dbd1be -[NSISEngine withBehaviors:performModifications:] + 155
    6   UIKit                               0x00000001039bc83a __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke + 452
    7   UIKit                               0x00000001039bc64d -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] + 197
    8   UIKit                               0x00000001039bc933 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke_2 + 217
    9   Foundation                          0x0000000101dbd1be -[NSISEngine withBehaviors:performModifications:] + 155
    10  UIKit                               0x00000001039bc83a __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke + 452
    11  UIKit                               0x00000001039bc64d -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] + 197
    12  UIKit                               0x00000001039bc933 __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke_2 + 217
    13  Foundation                          0x0000000101dbd1be -[NSISEngine withBehaviors:performModifications:] + 155
    14  UIKit                               0x00000001039bc83a __57-[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:]_block_invoke + 452
    15  UIKit                               0x00000001039bc64d -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] + 197
    16  UIKit                               0x00000001033b5717 __40-[UIView(Hierarchy) layoutBelowIfNeeded]_block_invoke + 39
    17  Foundation                          0x0000000101dbd1be -[NSISEngine withBehaviors:performModifications:] + 155
    18  UIKit                               0x00000001033b5556 -[UIView(Hierarchy) layoutBelowIfNeeded] + 320
    19  UIKit                               0x000000010374a394 -[_UIAlertControllerAnimatedTransitioning animateTransition:] + 470
    20  UIKit                               0x000000010344fa4e __56-[UIPresentationController runTransitionForCurrentState]_block_invoke + 1867
    21  UIKit                               0x000000010336562c _applyBlockToCFArrayCopiedToStack + 314
    22  UIKit                               0x00000001033654a6 _afterCACommitHandler + 533
    23  CoreFoundation                      0x0000000102873ca7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    24  CoreFoundation                      0x0000000102873c00 __CFRunLoopDoObservers + 368
    25  CoreFoundation                      0x0000000102869a33 __CFRunLoopRun + 1123
    26  CoreFoundation                      0x0000000102869366 CFRunLoopRunSpecific + 470
    27  GraphicsServices                    0x0000000106dd6a3e GSEventRunModal + 161
    28  UIKit                               0x0000000103341900 UIApplicationMain + 1282
    29  Observation                         0x0000000101612927 main + 135
    30  libdyld.dylib                       0x0000000104f60145 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

This bug is triggered if the UIAlertController's view is loaded when you calling -addTextFieldWithConfigurationHandler: ([alert isViewLoaded] == YES).

If you are accessing alert.view prior to calling -addTextFieldWithConfigurationHandler, move whatever you are doing with alert.view to after the call to -addTextFieldWithConfigurationHandler:.

Answer 2

This seems to have something to do with styling the UIAlertController's view, as eluded to by @BigShay.

In my example I set the tintColor of the view before adding the UITextField and I crash in iOS 8. The workaround given by @Baza207 to add the UITextField after displaying the alert avoids the crash in iOS 8, however it also results in no text field appearing at all in iOS 9.

If you just move the styling to after adding the text field, it works with both iOS 8 and iOS 9 (no crash in iOS 8, and no missing text field in iOS 9):

Crash in iOS 8

Works in iOS 9

alertController.view.tintColor = UIColor.blueColor()

alertController.addTextFieldWithConfigurationHandler { textField in
}

presentViewController(alertController, animated: true, completion: nil)

Works in iOS 8

No text text field in iOS 9

alertController.view.tintColor = UIColor.blueColor()

presentViewController(alertController, animated: true, completion: nil)

alertController.addTextFieldWithConfigurationHandler { textField in
}

Works in iOS 8

Works in iOS 9

alertController.addTextFieldWithConfigurationHandler { textField in
}

alertController.view.tintColor = UIColor.blueColor()

presentViewController(alertController, animated: true, completion: nil)

Answer 3

I just ran your code inside my test project — everything worked fine on 8.3.

View not found in container hierarchy:

This error usually appears if you mess up UIViewController child/parent relationship. There are few points to consider:

• the controller you are using to present alert is topmost and is not presenting anything else already
• parent controllers either have the one you use as a child (addChildViewController:) or are in a state of presenting it through either presentViewController:animated:completion: or the likes of it
• controller's view is loaded before presenting another ViewController

Also, there is definitely something wrong with the frames.

Answer 4

Try to set alert.view.frame explicitly to something small. I think by default it may be as big as the application view, triggering this on its subviews.

Answer 5

I really didn't like the solutions I saw and came up with an easier one. The crash occurs (for me, at least) when the keyboard is visible and an alert with an input field is presented.

I simply dismiss the keyboard prior to presenting the alert and then everything is fine.

Answer 6

Aha, I think this may be answered by jcesarmobile in another thread: UIAlertController/UIAlertView scrolling on iOS 8

The workaround a lot of folks added to deal with prior bugs with long text in UIAlertController now causes this crash in 8.3. And the long text issue is fixed in 8.3, so the workaround can be made conditional to avoid this in 8.3