//把bgView强制修改成UIControl,以便响应触摸事件

//UIControl是UIView的子类

//其实有很多情况都可以这样用，用一个普通的UIView来模拟某些控件，可以很灵活！！！！

 

UIView *bgView;

CGRect bgFrame = CGRectMake(0.0, 35.0, 320.0, 460.0 - 35.0);

UIControl *bgControl = [[UIControl alloc] initWithFrame:bgFrame];

[bgControl addTarget:self

action:@selector(resignKeyboardAction)

forControlEvents:UIControlEventTouchDown];

self.bgView = bgControl;

[bgControl release];

self.bgView.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.5];

self.bgView.hidden = YES;

[self.view addSubview:bgView];