Refactor private key detection logic

damus/Util/Keys.swift

@@ -158,6 +158,20 @@ func get_saved_privkey() -> String? {
     return mkey.map { $0.trimmingCharacters(in: .whitespaces) }
 }
 
+/**
+ Detects whether a string might contain an nsec1 prefixed private key.
+ It does not determine if it's the current user's private key and does not verify if it is properly encoded or has the right length.
+ */
+func contentContainsPrivateKey(_ content: String) -> Bool {
+    if #available(iOS 16.0, *) {
+        return content.contains(/nsec1[02-9ac-z]+/)
+    } else {
+        let regex = try! NSRegularExpression(pattern: "nsec1[02-9ac-z]+")
+        return (regex.firstMatch(in: content, range: NSRange(location: 0, length: content.count)) != nil)
+    }
+
+}
+
 fileprivate func removePrivateKeyFromUserDefaults() throws {
     guard let privKey = UserDefaults.standard.string(forKey: "privkey") else { return }
     try save_privkey(privkey: privKey)

damus/Views/DMChatView.swift

@@ -97,12 +97,7 @@ struct DMChatView: View {
                     Button(
                         role: .none,
                         action: {
-                            if #available(iOS 16.0, *) {
-                                showPrivateKeyWarning = message.contains(/nsec1[02-9ac-z]+/)
-                            } else {
-                                let regex = try! NSRegularExpression(pattern: "nsec1[02-9ac-z]+")
-                                showPrivateKeyWarning = (regex.firstMatch(in: message, range: NSRange(location: 0, length: message.count)) != nil)
-                            }
+                            showPrivateKeyWarning = contentContainsPrivateKey(message)
 
                             if !showPrivateKeyWarning {
                                 send_message()

damus/Views/PostView.swift

@@ -66,12 +66,7 @@ struct PostView: View {
 
                 if !is_post_empty {
                     Button(NSLocalizedString("Post", comment: "Button to post a note.")) {
-                        if #available(iOS 16.0, *) {
-                            showPrivateKeyWarning = self.post.contains(/nsec1[02-9ac-z]+/)
-                        } else {
-                            let regex = try! NSRegularExpression(pattern: "nsec1[02-9ac-z]+")
-                            showPrivateKeyWarning = (regex.firstMatch(in: self.post, range: NSRange(location: 0, length: self.post.count)) != nil)
-                        }
+                        showPrivateKeyWarning = contentContainsPrivateKey(self.post)
 
                         if !showPrivateKeyWarning {
                             self.send_post()