text_field: secure: true for masked password input

CHANGELOG.md

@@ -8,6 +8,22 @@ Full module documentation: [hexdocs.pm/mob](https://hexdocs.pm/mob).
 
 ---
 
+## [Unreleased]
+
+### Added
+- `text_field` now accepts a `secure: true` prop. iOS renders the field
+  as a SwiftUI `SecureField` (masked input) instead of the plain
+  `TextField`. The prop flows through the existing renderer
+  passthrough; cleartext still reaches the BEAM via `on_change` so apps
+  can hash/store the value as normal. Android consumes the same prop
+  via `PasswordVisualTransformation` once `mob_new`'s `MobBridge.kt.eex`
+  template is updated in a companion PR — until then the prop is a
+  graceful no-op on Android (renders as a regular field), no breakage.
+
+  Reveal-toggle ("eye" button) is intentionally deferred — its
+  interaction with SwiftUI focus retention requires a `ZStack`-and-opacity
+  rebuild of `MobTextField` and warrants its own change.
+
 ## [0.6.7]
 
 ### Added

ios/MobNode.h

@@ -125,6 +125,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property(nonatomic, copy, nonnull)
     NSString *keyboardTypeStr; // "default","number","decimal","email","phone","url"
 @property(nonatomic, copy, nonnull) NSString *returnKeyStr; // "done","next","go","search","send"
+@property(nonatomic, assign) BOOL isSecure;                 // mask input (SecureField on iOS)
 @property(nonatomic, copy, nullable) void (^onFocus)(void);
 @property(nonatomic, copy, nullable) void (^onBlur)(void);
 @property(nonatomic, copy, nullable) void (^onSubmit)(void);

ios/MobRootView.swift

@@ -1028,8 +1028,17 @@ private struct MobTextField: View {
         }
     }
 
+    @ViewBuilder
+    private var field: some View {
+        if node.isSecure {
+            SecureField(placeholder, text: $text)
+        } else {
+            TextField(placeholder, text: $text)
+        }
+    }
+
     var body: some View {
-        TextField(placeholder, text: $text)
+        field
             .focused($isFocused)
             .keyboardType(keyboardType)
             .submitLabel(submitLabel)

ios/mob_nif.m

@@ -797,6 +797,10 @@ static void mob_send_change_float(int handle, double value) {
         if ([returnKey isKindOfClass:[NSString class]])
             node.returnKeyStr = returnKey;
 
+        id secure = props[@"secure"];
+        if ([secure isKindOfClass:[NSNumber class]])
+            node.isSecure = [secure boolValue];
+
         id onFocus = props[@"on_focus"];
         if (onFocus && [onFocus isKindOfClass:[NSNumber class]]) {
             int handle = [onFocus intValue];

test/mob/renderer_test.exs

@@ -544,6 +544,22 @@ defmodule Mob.RendererTest do
       assert decoded["props"]["return_key"] == "next"
     end
 
+    test "secure boolean is passed through unchanged" do
+      tree = %{type: :text_field, props: %{value: "", secure: true}, children: []}
+      Renderer.render(tree, :android, MockNIF)
+      {:set_root, [json]} = Enum.find(MockNIF.calls(), fn {f, _} -> f == :set_root end)
+      decoded = :json.decode(json)
+      assert decoded["props"]["secure"] == true
+    end
+
+    test "secure defaults to absent when unset" do
+      tree = %{type: :text_field, props: %{value: ""}, children: []}
+      Renderer.render(tree, :android, MockNIF)
+      {:set_root, [json]} = Enum.find(MockNIF.calls(), fn {f, _} -> f == :set_root end)
+      decoded = :json.decode(json)
+      refute Map.has_key?(decoded["props"], "secure")
+    end
+
     test "register_tap receives {pid, tag} for tagged taps" do
       pid = self()
       tree = %{type: :button, props: %{text: "Tap", on_tap: {pid, :my_action}}, children: []}