UIWindow subclass that adds rounded top corners.

MyWindow.h

@interface MyWindow : UIWindow

@end

MyWindow.m

#import <QuartzCore/QuartzCore.h>
#import "MyWindow.h"

@implementation MyWindow

- (void)layoutSubviews
{
    [super layoutSubviews];
    
    CGRect frame = [UIScreen mainScreen].applicationFrame;
    UIBezierPath *innerPath = [UIBezierPath bezierPathWithRoundedRect:frame byRoundingCorners:UIRectCornerTopLeft|UIRectCornerTopRight cornerRadii:CGSizeMake(5.0f, 5.0f)];
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.path = innerPath.CGPath;
    self.layer.mask = maskLayer;
}

@end