解决办法:
创建控制器. File->New File->Iphone OS->Cocoa Touch Class->UIViewController subclass;
创建xib. File->New File->Iphone OS->User Interface->View XIB
绑定controller和view. 用Interface Builder打开xxx.xib, 点击Files’ Owner, 在Identity Inspector里面的Class Identity, 选择Step 1创建的控制器类, 接着拖拽File’s Owner到View中, 选择Outlets->view.先选中file’s owner(这个很重要)