UIBezierPath *maskPath;
 maskPath = [UIBezierPath bezierPathWithRoundedRect:YourImageVIew.bounds byRoundingCorners:(UIRectCornerTopRight | UIRectCornerBottomRight) cornerRadii:CGSizeMake(50.0,50.0)];

 CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
 maskLayer.frame = YourImageVIew.bounds;
 maskLayer.path = maskPath.CGPath;
 YourImageVIew.layer.mask = maskLayer;