# Deep links and navigation
## Intent
Route external URLs into in-app destinations while falling back to system handling when needed.
## Core patterns
- Centralize URL handling in the router (`handle(url:)`, `handleDeepLink(url:)`).
- Inject an `OpenURLAction` handler that delegates to the router.
- Use `.onOpenURL` for app scheme links and convert them to web URLs if needed.
- Let the router decide whether to navigate or open externally.
## Example: router entry points
```swift
@MainActor
final class RouterPath {
var path: [Route] = []
var urlHandler: ((URL) -> OpenURLAction.Result)?
func handle(url: URL) -> OpenURLAction.Result {
if isInternal(url) {
navigate(to: .status(id: url.lastPathComponent))
return .handled
}
return urlHandler?(url) ?? .systemAction
}
func handleDeepLink(url: URL) -> OpenURLAction.Result {
// Resolve federated URLs, then navigate.
navigate(to: .status(id: url.lastPathComponent))
return .handled
}
}
```
## Example: attach to a root view
```swift
extension View {
func withLinkRouter(_ router: RouterPath) -> some View {
self
.environment(
\.openURL,
OpenURLAction { url in
router.handle(url: url)
}
)
.onOpenURL { url in
router.handleDeepLink(url: url)
}
}
}
```
## Design choices to keep
- Keep URL parsing and decision logic inside the router.
- Avoid handling deep links in multiple places; one entry point is enough.
- Always provide a fallback to `OpenURLAction` or `UIApplication.shared.open`.
## Pitfalls
- Don’t assume the URL is internal; validate first.
- Avoid blocking UI while resolving remote links; use `Task`.
