Force canvas/text input focus on touch for iOS web browsers (#4848)

crates/eframe/src/web/mod.rs

@@ -264,3 +264,16 @@ pub fn percent_decode(s: &str) -> String {
         .decode_utf8_lossy()
         .to_string()
 }
+
+/// Returns `true` if the app is likely running on a mobile device.
+pub(crate) fn is_mobile() -> bool {
+    fn try_is_mobile() -> Option<bool> {
+        const MOBILE_DEVICE: [&str; 6] =
+            ["Android", "iPhone", "iPad", "iPod", "webOS", "BlackBerry"];
+
+        let user_agent = web_sys::window()?.navigator().user_agent().ok()?;
+        let is_mobile = MOBILE_DEVICE.iter().any(|&name| user_agent.contains(name));
+        Some(is_mobile)
+    }
+    try_is_mobile().unwrap_or(false)
+}