iOS 9b4: Receiving warning in the console about redundant NSLayoutConstraints when opening a UIActivityViewController

Number:rdar://22113188 Date Originated:03-Aug-2015 02:29 PM
Status:Resolved Resolved:Beta 5
Product:iOS SDK Product Version:iOS 9b4
Classification:UI/Usability Reproducible:Always
Presenting a UIActivityViewController by calling [self presentViewController:animated:completion:] brings the following warning in the console:
“Attempt to add this NSLayoutConstraint to an engine in which it already exists.  This can cause engine corruption. Break on void _NSLayoutConstraintRedundantAdd() to debug.  This will be logged only once.  This may break in the future.”

Steps to Reproduce:
1. Execute the attached project on the iPad 2 simulator (didn’t test for any others)
2. Tap the “Open UIActivityViewController”-button
3. The warning should now be visible in the debugging-console

Expected Results:
There shouldn’t be any warning on the console when executing this program.

Actual Results:
It shows the mentioned warning.

Didn’t appear in iOS 8

Provide additional information, such as references to related problems, workarounds and relevant attachments.


The example project can be found at

By raise.rescue at Aug. 3, 2015, 12:40 p.m. (reply...)

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