iOS 8 Snapshotting a view that has not been rendered results in an empty snapshot

Question

In iOS 8 I am having problem capturing images from camera till now I am using this code for   UIImagePickerController  controller   UIImagePickerController alloc  init   controller videoQuality UIImagePickerControllerQualityTypeMedium  controller delegate  id self  controller sourceType UIImagePickerControllerSourceTypeCamera   self presentViewController controller animated YES completion nil     But in iOS 8 I am getting this   Snapshotting a view that has not been rendered results in an empty snapshot  Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates    I have tried with the solution provided by This Post with    property  strong nonatomic UIImagePickerController  controller    controller   UIImagePickerController alloc  init    controller videoQuality UIImagePickerControllerQualityTypeMedium   controller delegate  id self   controller sourceType UIImagePickerControllerSourceTypeCamera    self presentViewController controller animated YES completion nil     and this      controller modalPresentationStyle UIModalPresentationFullScreen  or controller modalPresentationStyle UIModalPresentationCurrentContext        and this  double delayInSeconds   0 1  dispatch time t popTime   dispatch time DISPATCH TIME NOW  delayInSeconds   NSEC PER SEC   dispatch after popTime  dispatch get main queue      void        self presentViewController controller animated YES completion nil         and this   self presentViewController controller animated YES completion NULL     and this   self presentViewController controller animated YES completion           any idea

User · Answer

If we are using the UIImagePickerController as a property  then this warning will disappear  xcode assume that we are not using the result from the UIImagePickerController   if we are instantiating the UIImagePickerController within a function

User · Answer

Calling this method worked for me  Place it after presenting your view    yourViewBeingPresented view layoutIfNeeded

User · Answer

I found the same issue and tried everything  I have two different apps  one in objective-C and one in swift - both have the same problem  The error message comes in the debugger and the screen goes black after the first photo  This only happens in iOS    8 0  obviously it is a bug   I found a difficult workaround  Shut off the camera controls with         imagePicker showsCameraControls   false and create your own overlayView that has the missing buttons  There are various tutorials around how to do this   The strange error message stays  but at least the screen doesn t go black and you have a working app

User · Answer

I had this with an UIAlertControllerStyleActionSheet giving the user the option to take a photo with the camera or use one from library   I tried a symbolic breakpoint on the error message   That showed me the error is produced by the intern use of a UICollectionView during presentation   self presentViewController alert animated YES completion nil       I fixed this by explixitly setting the frame before presenting   alert setPreferredContentSize  alert view frame size     Here is the complete methode that is working without the error  - void showImageSourceAlertFromSender  id sender  UIButton  senderButton    UIButton  sender  UIAlertController  alert    UIAlertController alertControllerWithTitle nil message nil preferredStyle UIAlertControllerStyleActionSheet   UIAlertAction  cameraAction    UIAlertAction actionWithTitle   Camera  style UIAlertActionStyleDefault                                                      handler   UIAlertAction  action                                                              self takePhoto                                                            UIAlertAction  libraryAction    UIAlertAction actionWithTitle   Library  style UIAlertActionStyleDefault                                                       handler   UIAlertAction  action                                                               self selectPhotoFromLibraryFromSender sender                                                              alert addAction cameraAction    alert addAction libraryAction   alert popoverPresentationController delegate   self  alert popoverPresentationController sourceRect   senderButton frame  alert popoverPresentationController sourceView   self view    alert setPreferredContentSize  alert view frame size     self presentViewController alert animated YES completion

User · Answer

I have came across with this issue  When we call the camera and release the views produced this issue  For an example call an camera and set view nil in viewDidDisappear method this error will come since there is not callback for camera event  Make sure about this case too for this error

User · Answer

I m using Phonegap  but this thread keeps coming as the first one when Googling about the error message   For me this issue went away by defining the imagetype to PNG   encodingType   Camera EncodingType PNG   So the whole line being    navigator camera getPicture successFunction  failFunction    encodingType   Camera EncodingType PNG  correctOrientation true  sourceType   Camera PictureSourceType     PHOTOLIBRARY  quality  70  allowEdit   false   destinationType  Camera DestinationType DATA URL      Your mileage may vary  but that did the trick for me

User · Answer

I ran into this after calling UIImagePickerController presentViewController  from the callback to a UIAlertView delegate   I solved the issue by pushing the presentViewController  call off the current execution trace using dispatch async   -  void alertView  UIAlertView   alertView didDismissWithButtonIndex  NSInteger buttonIndex       dispatch async dispatch get main queue               UIImagePickerController  imagePickerController     UIImagePickerController alloc  init           imagePickerController delegate   self           if  buttonIndex    1              imagePickerController sourceType   UIImagePickerControllerSourceTypePhotoLibrary          else             imagePickerController sourceType   UIImagePickerControllerSourceTypeCamera            self presentViewController  imagePickerController                            animated  YES                          completion  nil

User · Answer

Alternatively  consider using drawViewHierarchyInRect   Swift   extension UIImage       class func renderUIViewToImage viewToBeRendered  UIView  - gt  UIImage               UIGraphicsBeginImageContextWithOptions viewToBeRendered bounds size  true  0 0          viewToBeRendered drawViewHierarchyInRect viewToBeRendered bounds  afterScreenUpdates  true          viewToBeRendered layer renderInContext UIGraphicsGetCurrentContext              let finalImage   UIGraphicsGetImageFromCurrentImageContext           UIGraphicsEndImageContext            return finalImage           Objective-C   -  UIImage   snapshot  UIView   view       UIGraphicsBeginImageContextWithOptions view bounds size  YES  0        view drawViewHierarchyInRect view bounds afterScreenUpdates YES       UIImage  image   UIGraphicsGetImageFromCurrentImageContext        UIGraphicsEndImageContext         return image      Also see    https   developer apple com library ios qa qa1817  index html How to capture UIView to UIImage without loss of quality on retina display

User · Answer

I don t have enough reputation points to comment on  greg s answer above  so will add my observations here   I have a Swift project for both iPad and iPhone   I have a method inside my main view controller  relevant bit below    When I test this on a phone  everything works properly and no warnings are generated   When I run it on an iPad  everything works properly but I see the warning about snapshotting the view   The interesting bit  however  is that when I run on an iPad without using the popover controller  everything works properly with no warning   Unfortunately  Apple mandates that the image picker must be used within a popover on iPad  if the camera is not being used       dispatch async dispatch get main queue              let imagePicker  UIImagePickerController   UIImagePickerController            imagePicker sourceType   UIImagePickerControllerSourceType SavedPhotosAlbum          imagePicker mediaTypes    kUTTypeImage           imagePicker allowsEditing   false          imagePicker delegate   self           if UIDevice currentDevice   userInterfaceIdiom     Pad      on a tablet  the image picker is supposed to be in a popover             let popRect  CGRect   buttonRect              let popover  UIPopoverController   UIPopoverController contentViewController  imagePicker               popover presentPopoverFromRect popRect  inView  self view  permittedArrowDirections  UIPopoverArrowDirection Up  animated  true            else              self presentViewController imagePicker  animated  true  completion  nil

User · Answer

I was struggling with this issue for several hours  i have read every relevant topic and found out that the error was caused because under the privacy settings of my device  the camera access to my app was blocked    I have never denied access to camera and i don t know how it was blocked but that was the problem

User · Answer

I ve tried everything  my problem was that the image picker for the camera and photo library disappeared right after they showed  I solved it with the following line  swift   imagePicker modalPresentationStyle   UIModalPresentationStyle OverCurrentContext

User · Answer

In my case   XCode 7 and iOS 9    I use UINavigationController  hidden   so Ihave to add UINavigationControllerDelegate to present camera or roll and it work like it is supposed to  And pickerControllerDelegate self doesn t display error either

User · Answer

For anyone that is seeing an issue with a black preview after image capture  hiding the status bar after the UIPickerController is shown seems to fix the issue   UIImagePickerControllerSourceType source    UIImagePickerController isSourceTypeAvailable UIImagePickerControllerSourceTypeCamera    UIImagePickerControllerSourceTypeCamera   UIImagePickerControllerSourceTypeSavedPhotosAlbum  UIImagePickerController  cameraController     UIImagePickerController alloc  init           cameraController delegate   self          cameraController sourceType   source          cameraController allowsEditing   YES           self presentViewController cameraController animated YES completion                  iOS 8 bug   the status bar will sometimes not be hidden after the camera is displayed  which causes the preview after an image is captured to be black             if  source    UIImagePickerControllerSourceTypeCamera                      UIApplication sharedApplication  setStatusBarHidden YES withAnimation UIStatusBarAnimationNone

User · Answer

I got the same bug getting bellow message in console while opening camera     Snapshotting a view that has not been rendered results in an empty snapshot  Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates    For me problem was with the Bundle display name in Info plist file it was empty some how i put my app name there and now it working fine i did t received any camera permission alert because of empty Bundle display name it blocked the view from rendering    the problem was t with view but by presenting it without a permission you can check it on settings-- privacy-- Camera if your app not listed there problem might be same

User · Answer

I m pretty sure this is just a bug in iOS 8 0  It s reproducible with the simplest of POC apps that does nothing more than attempt to present a UIImagePickerController like you re doing above  Furthermore  there s no alternative pattern to displaying the image picker camera  to my knowledge  You can even download Apple s Using UIImagePickerController sample app  run it  and it will generate the same error out of the box   That said  the functionality still works for me  Other than the warning error  do you have issues with the functioning of your app

User · Answer

I had this issue when animating some views and the app would go into background mode and come back  I handled it by setting a flag isActive  I set it to NO in  -  void applicationWillResignActive  UIApplication   application   and YES in  -  void applicationDidBecomeActive  UIApplication   application   and animate or not animate my views accordingly  Took care of the issue

User · Answer

This might be a bug of built-in ImagePickerController  My code is working  but occasionally crashes on iPhone 6 Plus   I ve tried all solutions suggested by other answers but there were no luck  Problem finally solved after switching to JPSImagePickerController

User · Answer

I m pretty sure this is just a bug in iOS 8 0   It s reproducible with the simplest of POC apps that does nothing more than attempt to present a UIImagePickerController like you re doing above   Furthermore  there s no alternative pattern to displaying the image picker camera  to my knowledge   You can even download Apple s Using UIImagePickerController sample app  run it  and it will generate the same error out of the box   That said  the functionality still works for me   Other than the warning error  do you have issues with the functioning of your app

User · Answer

You can silence the  Snapshotting a view  warning by referencing the view property before presenting the view controller  Doing so causes the view to load and allows iOS render it before taking the snapshot   UIAlertController  controller    UIAlertController alertControllerWithTitle nil message nil preferredStyle UIAlertControllerStyleActionSheet   controller modalPresentationStyle   UIModalPresentationPopover  controller popoverPresentationController barButtonItem    UIBarButtonItem   sender       setup the UIAlertController        controller view       lt --- Add to silence the warning    self presentViewController controller animated YES completion nil

User · Answer

I also encounter the same problem and I resolved it by checking if the camera is available   BOOL cameraAvailableFlag    UIImagePickerController isSourceTypeAvailable UIImagePickerControllerSourceTypeCamera       if  cameraAvailableFlag           self performSelector  selector showcamera  withObject nil afterDelay 0 3

[objective-c] iOS 8 Snapshotting a view that has not been rendered results in an empty snapshot

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