AwaitExample1.cs

public async Task<bool> DoesWebContentMatchPatternAsync(Uri uri, Regex pattern)
{
    HttpClient client = new HttpClient();
    string html = await client.GetStringAsync();
    bool matches = pattern.Matches(html);
    return matches;
}

AwaitExample2.cs

public async Task<bool> DoesWebContentMatchPatternAsync(Uri uri, Regex pattern)
{
    try
    {
        HttpClient client = new HttpClient();
        string html = await client.GetStringAsync();
        bool matches = pattern.Matches(html);
        return matches;
    }
    catch (Exception)
    {
        return false;
    }
}

AwaitExample3.cs

private async void Button_Click(object sender, RoutedEventArgs e)
{
    Uri uriToTest = new Uri(uriBox.Text);
    Regex expressionToTest = new Regex(@"\b(spoon|knife|fork)\b");
    bool matches = await DoesWebContentMatchPatternAsync(uriToTest, expressionToTest);
    resultBox.Text = matches.ToString();
}

AwaitExample4.cs

string html = await client.GetStringAsync().ConfigureAwait(false);

client.GetStringAsync(); should probably be client.GetStringAsync(uri);