edgesForExtendedLayout

ios默認viewController的View會延伸到最頂端，即便上面有導航條、狀態欄，能夠設置edgesForExtendedLayout屬性

f([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0){
        
        self.edgesForExtendedLayout = UIRectEdgeNone;
        self.automaticallyAdjustsScrollViewInsets = NO;
        
    }