xcode 8.3 ,ios 10.3 ,cell高度计算不准确

cell布局使用xib AutoLayout, 添加的约束没问题,label没有随内容换行,控制台有约束报错信息:
Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
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求解