xcode4调试报错exc_bad_access

EXC_BAD_ACCESS is not an exception, at least not as far as breakpoints are concerned - it means the code is trying to call a method on an object that does not exist anymore, because you released it.

The easiest way to find this in XCode4 is to run Instruments (Cmd-I), and in the dialog that pops up asking you which instrument to use, choose "Zombies". Then do whatever to cause the crash, and you will see a dialog pop up with "Zombie Messaged". Click on the little arrow and you will get a history of what created, retained, or released the object. Then you can figure out who released the object early.

To edit environment variables, go to Menu Product / Edit Scheme…, select the desired configuration (you probably want 'Run') from the left sidebar first and then click on the Arguments tab. Environment variables are configurable there.

错误原因为提前release。找不到引用。可以设置调式工具来查看哪里报错：选择 menu－》product－》edit scheme 

在左边导航选择run。。选项，右边点击arguments 标签。在environment variables中配置