I’m working on a SwiftUI screen where I need to hide a header when the user scrolls down and show it again when the user scrolls up. I’m currently using a ScrollView combined with GeometryReader to detect scroll offset changes and update state variables like isScrolling or isScrollingDown. The issue is that the behavior is inconsistent. When I scroll down, the header hides correctly, but when I scroll back up, the header often doesn’t appear again even though the offset is changing. Sometimes the header comes back with a delay, and other times it never appears at all. Along with this, I’m also seeing noticeable UI lag whenever I try to calculate content height or read multiple geometry values inside the ScrollView. It looks like the frequent state updates inside the scroll offset tracking are causing layout recalculations and frame drops. I’ve tried placing the header in different positions (inside a ZStack aligned to the top, inside the VStack above the ScrollView, and with transitions like .push(from: .top)), but the result is still the same: smooth scrolling breaks, and the header doesn’t reliably animate back when scrolling upward. What I’m looking for is a minimal and efficient approach to detect scroll direction and trigger the header hide/show animation without causing performance issues or recomputing expensive layout values. Any guidance or a simplified pattern that works well for dynamic headers in SwiftUI would be very helpful. if isScrolling { headerStackView() //Includes Navigation Bar .transition( .asymmetric( insertion: .push(from: .top), removal: .push(from: .bottom) ) ) } GeometryReader { outer in let outerHeight = outer.size.height ScrollView(.vertical) { VStack { content() // Heavy view + contains its own ScrollView } .background { GeometryReader { proxy in let contentHeight = proxy.size.height let minY = max( min(0, proxy.frame(in: .named("ScrollView")).minY), outerHeight - contentHeight ) if #available(iOS 17.0, *) { Color.clear .onChange(of: minY) { oldVal, newVal in // Scroll direction detection if (isScrolling && newVal < oldVal) || (!isScrolling && newVal > oldVal) { isScrolling = newVal > oldVal } } } } } } .coordinateSpace(name: "ScrollView") } .padding(.top, 1)

We are facing a DNS resolution issue with a specific ISP, where our domain name does not resolve correctly using the system DNS. However, the same domain works as expected when a custom DNS resolver is used. On Android, this is straightforward to handle by configuring a custom DNS implementation using OkHttp / Retrofit. I am trying to implement a functionally equivalent solution in native iOS (Swift / SwiftUI). Android Reference (Working Behavior) : val dns = DnsOverHttps.Builder() .client(OkHttpClient()) .url("https://cloudflare-dns.com/dns-query".toHttpUrl()) .bootstrapDnsHosts(InetAddress.getByName("1.1.1.1")) .build() OkHttpClient.Builder() .dns(dns) .build() Attempted iOS Approach I attempted the following approach : Resolve the domain to an IP address programmatically (using DNS over HTTPS) Connect directly to the resolved IP address Set the original domain in the Host HTTP header DNS Resolution via DoH : func resolveDomain(domain: String) async throws -> String {     guard let url = URL(         string: "https://cloudflare-dns.com/dns-query?name=\(domain)&type=A"     ) else {         throw URLError(.badURL)     }     var request = URLRequest(url: url)     request.setValue("application/dns-json", forHTTPHeaderField: "accept")     let (data, _) = try await URLSession.shared.data(for: request)     let response = try JSONDecoder().decode(DNSResponse.self, from: data)     guard let ip = response.Answer?.first?.data else {         throw URLError(.cannotFindHost)     }     return ip } API Call Using Resolved IP :  func callAPIUsingCustomDNS() async throws {     let ip = try await resolveDomain(domain: "example.com")     guard let url = URL(string: "https://(ip)") else {         throw URLError(.badURL)     }     let configuration = URLSessionConfiguration.ephemeral     let session = URLSession(         configuration: configuration,         delegate: CustomURLSessionDelegate(originalHost: "example.com"),         delegateQueue: .main     )     var request = URLRequest(url: url)     request.setValue("example.com", forHTTPHeaderField: "Host")     let (_, response) = try await session.data(for: request)     print("Success: (response)") } Problem Encountered When connecting via the IP address, the TLS handshake fails with the following error: Error Domain=NSURLErrorDomain Code=-1200 "A TLS error caused the secure connection to fail." This appears to happen because iOS sends the IP address as the Server Name Indication (SNI) during the TLS handshake, while the server’s certificate is issued for the domain name. Custom URLSessionDelegate Attempt :  class CustomURLSessionDelegate: NSObject, URLSessionDelegate {     let originalHost: String     init(originalHost: String) {         self.originalHost = originalHost     }     func urlSession(         _ session: URLSession,         didReceive challenge: URLAuthenticationChallenge,         completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void     ) {         guard challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust,               let serverTrust = challenge.protectionSpace.serverTrust else {             completionHandler(.performDefaultHandling, nil)             return         }         let sslPolicy = SecPolicyCreateSSL(true, originalHost as CFString)         let basicPolicy = SecPolicyCreateBasicX509()         SecTrustSetPolicies(serverTrust, [sslPolicy, basicPolicy] as CFArray)         var error: CFError?         if SecTrustEvaluateWithError(serverTrust, &error) {             completionHandler(.useCredential, URLCredential(trust: serverTrust))         } else {             completionHandler(.cancelAuthenticationChallenge, nil)         }     } } However, TLS validation still fails because the SNI remains the IP address, not the domain. I would appreciate guidance on the supported and App Store–compliant way to handle ISP-specific DNS resolution issues on iOS. If custom DNS or SNI configuration is not supported, what alternative architectural approaches are recommended by Apple?

We are facing a DNS resolution issue with a specific ISP, where our domain name does not resolve correctly using the system DNS. However, the same domain works as expected when a custom DNS resolver is used. On Android, this is straightforward to handle by configuring a custom DNS implementation using OkHttp / Retrofit. I am trying to implement a functionally equivalent solution in native iOS (Swift / SwiftUI). **Android Reference (Working Behavior) : ** val dns = DnsOverHttps.Builder() .client(OkHttpClient()) .url("https://cloudflare-dns.com/dns-query".toHttpUrl()) .bootstrapDnsHosts(InetAddress.getByName("1.1.1.1")).build() OkHttpClient.Builder().dns(dns).build() **Attempted iOS Approach ** I attempted the following approach : Resolve the domain to an IP address programmatically (using DNS over HTTPS) Connect directly to the resolved IP address Set the original domain in the Host HTTP header **DNS Resolution via DoH : ** func resolveDomain(domain: String) async throws -> String { guard let url = URL( string: "https://cloudflare-dns.com/dns-query?name=\(domain)&type=A" ) else { throw URLError(.badURL) } var request = URLRequest(url: url) request.setValue("application/dns-json", forHTTPHeaderField: "accept") let (data, _) = try await URLSession.shared.data(for: request) let response = try JSONDecoder().decode(DNSResponse.self, from: data) guard let ip = response.Answer?.first?.data else { throw URLError(.cannotFindHost) } return ip } **API Call Using Resolved IP : ** func callAPIUsingCustomDNS() async throws { let ip = try await resolveDomain(domain: "example.com") guard let url = URL(string: "https://\(ip)") else { throw URLError(.badURL) } let configuration = URLSessionConfiguration.ephemeral let session = URLSession( configuration: configuration, delegate: CustomURLSessionDelegate(originalHost: "example.com"), delegateQueue: .main ) var request = URLRequest(url: url) request.setValue("example.com", forHTTPHeaderField: "Host") let (_, response) = try await session.data(for: request) print("Success: \(response)") } **Problem Encountered ** When connecting via the IP address, the TLS handshake fails with the following error: Error Domain=NSURLErrorDomain Code=-1200 "A TLS error caused the secure connection to fail." This appears to happen because iOS sends the IP address as the Server Name Indication (SNI) during the TLS handshake, while the server’s certificate is issued for the domain name. **Custom URLSessionDelegate Attempt : ** class CustomURLSessionDelegate: NSObject, URLSessionDelegate { let originalHost: String init(originalHost: String) { self.originalHost = originalHost } func urlSession( _ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void ) { guard challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust, let serverTrust = challenge.protectionSpace.serverTrust else { completionHandler(.performDefaultHandling, nil) return } let sslPolicy = SecPolicyCreateSSL(true, originalHost as CFString) let basicPolicy = SecPolicyCreateBasicX509() SecTrustSetPolicies(serverTrust, [sslPolicy, basicPolicy] as CFArray) var error: CFError? if SecTrustEvaluateWithError(serverTrust, &error) { completionHandler(.useCredential, URLCredential(trust: serverTrust)) } else { completionHandler(.cancelAuthenticationChallenge, nil) } } } However, TLS validation still fails because the SNI remains the IP address, not the domain. I would appreciate guidance on the supported and App Store–compliant way to handle ISP-specific DNS resolution issues on iOS. If custom DNS or SNI configuration is not supported, what alternative architectural approaches are recommended by Apple?