Fix updating stack config props. (#231)

When some of config props change or new header items are added we need to perform a header update. This diff adds logic to trigger updating header props when that happens.

android/src/main/java/com/swmansion/rnscreens/ScreenStackHeaderConfig.java

@@ -207,6 +207,12 @@ public class ScreenStackHeaderConfig extends ViewGroup {
     }
   }
 
+  private void maybeUpdate() {
+    if (getParent() != null) {
+      onUpdate();
+    }
+  }
+
   public ScreenStackHeaderSubview getConfigSubview(int index) {
     return mConfigSubviews[index];
   }
@@ -220,6 +226,7 @@ public class ScreenStackHeaderConfig extends ViewGroup {
       mSubviewsCount--;
     }
     mConfigSubviews[index] = null;
+    maybeUpdate();
   }
 
   public void addConfigSubview(ScreenStackHeaderSubview child, int index) {
@@ -227,6 +234,7 @@ public class ScreenStackHeaderConfig extends ViewGroup {
       mSubviewsCount++;
     }
     mConfigSubviews[index] = child;
+    maybeUpdate();
   }
 
   private TextView getTitleTextView() {

android/src/main/java/com/swmansion/rnscreens/ScreenStackHeaderConfigViewManager.java

@@ -52,6 +52,12 @@ public class ScreenStackHeaderConfigViewManager extends ViewGroupManager<ScreenS
     return true;
   }
 
+  @Override
+  protected void onAfterUpdateTransaction(ScreenStackHeaderConfig parent) {
+    super.onAfterUpdateTransaction(parent);
+    parent.onUpdate();
+  }
+
   @ReactProp(name = "title")
   public void setTitle(ScreenStackHeaderConfig config, String title) {
     config.setTitle(title);

ios/RNSScreen.m

@@ -114,6 +114,8 @@
 {
   if (![view isKindOfClass:[RNSScreenStackHeaderConfig class]]) {
     [super addSubview:view];
+  } else {
+    ((RNSScreenStackHeaderConfig*) view).screenView = self;
   }
 }
 

ios/RNSScreenStackHeaderConfig.h

@@ -1,8 +1,12 @@
 #import <React/RCTViewManager.h>
 #import <React/RCTConvert.h>
 
+#import "RNSScreen.h"
+
 @interface RNSScreenStackHeaderConfig : UIView
 
+@property (nonatomic, weak) RNSScreenView *screenView;
+
 @property (nonatomic, retain) NSString *title;
 @property (nonatomic, retain) NSString *titleFontFamily;
 @property (nonatomic, retain) NSNumber *titleFontSize;

ios/RNSScreenStackHeaderConfig.m

@@ -66,13 +66,36 @@
   return _reactSubviews;
 }
 
-- (UIViewController*)screen
+- (UIView *)reactSuperview
 {
-  UIView *superview = self.superview;
-  if ([superview isKindOfClass:[RNSScreenView class]]) {
-    return ((RNSScreenView *)superview).controller;
+  return _screenView;
+}
+
+- (void)removeFromSuperview
+{
+  [super removeFromSuperview];
+  _screenView = nil;
+}
+
+- (void)updateViewControllerIfNeeded
+{
+  UIViewController *vc = _screenView.controller;
+  UINavigationController *nav = (UINavigationController*) vc.parentViewController;
+  if (vc != nil && nav.visibleViewController == vc) {
+    [RNSScreenStackHeaderConfig updateViewController:self.screenView.controller withConfig:self];
   }
-  return nil;
+}
+
+- (void)didSetProps:(NSArray<NSString *> *)changedProps
+{
+  [super didSetProps:changedProps];
+  [self updateViewControllerIfNeeded];
+}
+
+- (void)didUpdateReactSubviews
+{
+  [super didUpdateReactSubviews];
+  [self updateViewControllerIfNeeded];
 }
 
 + (void)setAnimatedConfig:(UIViewController *)vc withConfig:(RNSScreenStackHeaderConfig *)config
@@ -142,6 +165,11 @@
 }
 
 + (void)willShowViewController:(UIViewController *)vc withConfig:(RNSScreenStackHeaderConfig *)config
+{
+  [self updateViewController:vc withConfig:config];
+}
+
++ (void)updateViewController:(UIViewController *)vc withConfig:(RNSScreenStackHeaderConfig *)config
 {
   UINavigationItem *navitem = vc.navigationItem;
   UINavigationController *navctr = (UINavigationController *)vc.parentViewController;