iOS 常见错误：CALayer position contains NaN: [14 nan]

Terminating app due to uncaught exception 'CALayerInvalidGeometry', reason: 'CALayer position contains NaN: [14 nan]'
*** First throw call stack:
　　这个主要在画layer的时候，计算未考虑0的情况，在除数为0的时候就会报错，去检查把，骚年~~