ios 7 20像素解决

1、if ([[[UIDevicecurrentDevice] systemVersion] floatValue] >= 7) {

        self.view.bounds = CGRectMake(0, -20, self.view.frame.size.width, self.view.frame.size.height );

    }

2、http://www.ifun.cc/blog/2013/09/28/gua-pei-ios7kai-fa/