iOS 断言

NSAssert
定义：#define NSAssert(condition, desc, ...) //第一个参数bool值，如果为真就跳过，假就抛出异常，

2017-03-28 11:09:35.620 test[53230:6340827] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'str is nil'

'str is nil'即为desc

参考文章