UIScreen类

 CGRect screenBounds = [ [UIScreen mainScreen]bounds];//返回的是带有状态栏的Rect
     NSLog(@"%@", NSStringFromCGRect(screenBounds));

    CGRect viewBounds = [ [UIScreen mainScreen]applicationFrame];//不包含状态栏的Rect
     NSLog(@"%@", NSStringFromCGRect(viewBounds));

    CGRect statusBarRect = [[UIApplication sharedApplication]statusBarFrame];
     NSLog(@"%@", NSStringFromCGRect(statusBarRect));