Swing line can help identify resistance and support. Breaking resistance indicate an uptrend. Breaking support indicates a downtrend. This is a simple and intuitive method in trend determination.
However, many chart readers nowadays set Candlestick as preferred pattern. The shared indicator provides another choice for constructing swing lines.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.