错误代码：
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[UIViewController _loadViewFromNibNamed:bundle:] loaded the "ViewController" nib but the view outlet was not set.'
由于xib是我新建关联控制器的，在设置了nsobject控制器后没有关联控制器的view，导致出错。
