Open Radar

 
Summary:
When editing a SceneKit particle system, the warmup duration can be set to a negative number, when Xcode tries to apply this setting it hangs, requiring a force quit.
I have attached a sample project with a particle system for ease of testing, although this bug will occur with any project.

Steps to Reproduce:
Create a new SceneKit Particle System File. (Or select the particle system from the project navigator in the attached example project.)
In the right sidebar set the warmup duration to a negative number.
Refresh the particle system by either pressing the refresh icon, or clicking another file, then back to the particle system.

Expected Results:
Xcode should not hang. The warmup duration setting should be applied, or if negative numbers are not supported it should either default to 0  or not allow negative numbers to be selected through the interface.

Actual Results:
Xcode hangs when trying to display a particle system with negative warmup duration, requiring a force quit.

Version:
Xcode Version 7.3.1 (7D1014)

Notes:
I assume negative numbers are not supported, so can ensure not to set them.