Add example usage to README.md

README.md

@@ -1,2 +1,75 @@
 # espasyncmdns
 ESP32 async mdns search
+
+## Example usage
+```C++
+#include <chrono>
+#include <esp_log.h>
+#include <arrayview.h>
+#include <espwifiutils.h>
+
+#include <asyncmdnssearch.h>
+
+using namespace std::chrono_literals;
+
+namespace {
+constexpr const char * const TAG = "MYAPP";
+} // namespace
+
+AsyncMdnsSearch mdnsSearch;
+
+void startSearch()
+{
+    ESP_LOGI(TAG, "starting search...");
+
+    if (mdnsSearch.searchStarted())
+    {
+        ESP_LOGE(TAG, "search already started?!");
+        return;
+    }
+
+    if (const auto result = mdnsSearch.startSearch(nullptr, "_http", "_tcp", MDNS_TYPE_PTR, 5s, 20); !result)
+    {
+        ESP_LOGE(TAG, "could not start search: %.*s", result.error().size(), result.error().data());
+        return;
+    }
+
+    ESP_LOGI(TAG, "MDNS search started!");
+}
+
+void checkResults()
+{
+    if (!mdnsSearch.searchStarted())
+        return;
+
+    if (const auto results = mdnsSearch.getResults())
+    {
+        ESP_LOGI(TAG, "got results! %zd", results->size());
+
+        for (const mdns_result_t &result : *results)
+        {
+            ESP_LOGI(TAG, "result: "
+                          "tcpip_if=%i "
+                          "ip_protocol=%i "
+                          "instance_name=%s "
+                          "hostname=%s "
+                          "port=%hhu ",
+                     result.tcpip_if,
+                     result.ip_protocol,
+                     result.instance_name ? result.instance_name : "<null>",
+                     result.hostname ? result.hostname : "<null>",
+                     result.port);
+
+            if (result.txt_count && result.txt)
+                for (const mdns_txt_item_t &txtRecord : cpputils::ArrayView<mdns_txt_item_t>{result.txt, result.txt_count})
+                    ESP_LOGI(TAG, "  txt %s %s",
+                             txtRecord.key ? txtRecord.key : "<null>",
+                             txtRecord.value ? txtRecord.value : "<null>"
+                    );
+
+            for (mdns_ip_addr_t *addr = result.addr; addr; addr = addr->next)
+                ESP_LOGI(TAG, "  addr %s", wifi_stack::toString(addr->addr).c_str());
+        }
+    }
+}
+```