public void Replace()
        {
            using (var s = new NSMutableString(0)) {
                s.SetString((NSString)"Hello World");

                var number = s.ReplaceOcurrences((NSString)"World", (NSString)"Xamarin",
                                                 NSStringCompareOptions.CaseInsensitiveSearch, new NSRange(0, s.Length));
#if XAMCORE_2_0
                Assert.That(number, Is.EqualTo((nuint)1), "Number of replacements");
#else
                Assert.That(number, Is.EqualTo(1), "Number of replacements");
#endif
                Assert.That(s.ToString(), Is.EqualTo("Hello Xamarin"), "replaced");

                Assert.Throws <ArgumentOutOfRangeException> (delegate {
                    s.ReplaceOcurrences((NSString)"Xamarin", (NSString)"World!",
                                        NSStringCompareOptions.CaseInsensitiveSearch, new NSRange(0, s.Length + 1));
                }, "bad 1");

                Assert.Throws <ArgumentOutOfRangeException> (delegate {
                    s.ReplaceOcurrences((NSString)"Xamarin", (NSString)"World!",
                                        NSStringCompareOptions.CaseInsensitiveSearch, new NSRange(1, s.Length));
                }, "bad 2");
            }
        }