上週五將OS X升級到10.8.2
然後將Xcode升級到4.5.2，然後在IOS5上運行正常的應用在IOS6上就出現了一些問題，這篇就說說：Could not instantiate class named NSLayoutConstraint這個錯誤。
錯誤詳細信息如下：
*** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named NSLayoutConstraint'
*** First throw call stack:
(0x3587488f 0x33498259 0x35874789 0x358747ab 0x3325b54d 0x3325b6bb 0x3325b423 0x331ec001 0x3315a3c7 0x33037c59 0x32fadc17 0x32fac461 0x32f9ee87 0x3300f7d5 0x8d75d 0x32faccab 0x32fa67dd 0x32f74ac3 0x32f74567 0x32f73f3b 0x3356622b 0x35848523 0x358484c5 0x35847313
0x357ca4a5 0x357ca36d 0x32fa586b 0x32fa2cd5 0x8d535 0x8d4d0)
terminate called throwing an exception
解決辦法：
1）選中xib文件
2）選中 Show The File Inspector，然後將use autolayout 複選框去掉
