automatically get username and full user name (#4674)

Samples/iOS-Swift/iOS-Swift.xcodeproj/xcshareddata/xcschemes/iOS-Swift.xcscheme

@@ -264,6 +264,11 @@
             value = ""
             isEnabled = "NO">
          </EnvironmentVariable>
+         <EnvironmentVariable
+            key = "--io.sentry.user.name"
+            value = ""
+            isEnabled = "NO">
+         </EnvironmentVariable>
       </EnvironmentVariables>
    </LaunchAction>
    <ProfileAction

Samples/iOS-Swift/iOS-Swift/SentrySDKWrapper.swift

@@ -90,11 +90,8 @@ struct SentrySDKWrapper {
 
         let user = User(userId: "1")
         user.email = self.env["--io.sentry.user.email"] ?? "[email protected]"
-        // first check if the username has been overridden in the scheme for testing purposes; then try to use the system username so each person gets an automatic way to easily filter things on the dashboard; then fall back on a hardcoded value if none of these are present
-        let username = self.env["--io.sentry.user.username"] ?? (self.env["SIMULATOR_HOST_HOME"] as? NSString)?
-            .lastPathComponent ?? "cocoadev"
         user.username = username
-        user.name = self.env["--io.sentry.user.name"] ?? "cocoa developer"
+        user.name = userFullName
         scope.setUser(user)
 
         if let path = Bundle.main.path(forResource: "Tongariro", ofType: "jpg") {
@@ -105,6 +102,23 @@ struct SentrySDKWrapper {
         }
         return scope
     }
+
+    var userFullName: String {
+        let name = self.env["--io.sentry.user.name"] ?? NSFullUserName()
+        guard !name.isEmpty else {
+            return "cocoa developer"
+        }
+        return name
+    }
+
+    var username: String {
+        let username = self.env["--io.sentry.user.username"] ?? NSUserName()
+        guard !username.isEmpty else {
+            return (self.env["SIMULATOR_HOST_HOME"] as? NSString)?
+                .lastPathComponent ?? "cocoadev"
+        }
+        return username
+    }
 }
 
 // MARK: User feedback configuration