尝试支持present非fUIModalPresentationFullScreen样式的VC，但会闪烁

Author: 余玠

example/ios/Runner/NativeViewController.m

@@ -52,6 +52,7 @@ - (void)viewDidAppear:(BOOL)animated{
 //    [self.flutterContainer.view layoutIfNeeded];
 }
 
+//NOTES: embed情景下必须实现！！！
 - (void)didMoveToParentViewController:(UIViewController *)parent {
     [self.flutterContainer didMoveToParentViewController:parent];
     [super didMoveToParentViewController:parent];

ios/Classes/Boost/FLBFlutterApplicationInterface.h

@@ -66,6 +66,7 @@ NS_ASSUME_NONNULL_BEGIN
        onPageFinished:(void (^)(NSDictionary *))resultCallback
   completion:(void (^)(BOOL))completion;
 
+- (void)attachToPreviousContainer;
 
 - (void)didInitPageContainer:(NSString *)url
                       params:(NSDictionary *)urlParams

ios/Classes/Boost/FLBFlutterProvider.h

@@ -31,7 +31,7 @@ NS_ASSUME_NONNULL_BEGIN
 @protocol FLBFlutterProvider <NSObject>
 @required
 - (FlutterEngine *)engine;
-- (void)atacheToViewController:(FlutterViewController *)vc;
+- (BOOL)atacheToViewController:(FlutterViewController *)vc;
 - (void)detach;
 - (void)prepareEngineIfNeeded;
 - (void)pause;

ios/Classes/Engine/FLBFlutterApplication.m

@@ -31,6 +31,7 @@
 @interface FLBFlutterApplication()
 @property (nonatomic,strong) FLBFlutterContainerManager *manager;
 @property (nonatomic,strong) id<FLBFlutterProvider> viewProvider;
+@property (nonatomic, weak, readonly)FlutterViewController * previousViewController;
 @property (nonatomic,assign) BOOL isRunning;
 @property (nonatomic,strong) NSMutableDictionary *pageResultCallbacks;
 @property (nonatomic,strong) NSMutableDictionary *callbackCache;
@@ -157,6 +158,13 @@ - (FlutterViewController *)flutterViewController
     return self.flutterProvider.engine.viewController;
 }
 
+- (void)attachToPreviousContainer{
+    if([self.viewProvider atacheToViewController:self.previousViewController]){
+        [self.previousViewController.view setNeedsLayout];
+        [(FLBFlutterViewContainer*)self.previousViewController surfaceUpdated:YES];
+    }
+}
+
 - (void)close:(NSString *)uniqueId
        result:(NSDictionary *)resultData
          exts:(NSDictionary *)exts
@@ -190,7 +198,7 @@ - (void)open:(NSString *)url
         [newParams setObject:cid?cid:@"__default#0__" forKey:kPageCallBackId];
         urlParams = newParams;
     }
-    
+    _previousViewController = [self flutterViewController];
     _callbackCache[cid] = resultCallback;
     if([urlParams[@"present"]respondsToSelector:@selector(boolValue)] && [urlParams[@"present"] boolValue] && [self.platform respondsToSelector:@selector(present:urlParams:exts:completion:)]){
         [self.platform present:url

ios/Classes/Engine/FLBFlutterEngine.m

@@ -97,12 +97,13 @@ - (void)willEnterForeground
                          arguments:@{@"type":@"foreground"}];
 }
 
-- (void)atacheToViewController:(FlutterViewController *)vc
+- (BOOL)atacheToViewController:(FlutterViewController *)vc
 {
     if(_engine.viewController != vc){
-//        [(FLBFlutterViewContainer *)_engine.viewController surfaceUpdated:NO];
         _engine.viewController = vc;
+        return YES;
     }
+    return NO;
 }
 
 - (void)detach

ios/Classes/container/FLBFlutterViewContainer.m

@@ -287,11 +287,6 @@ - (void)viewDidDisappear:(BOOL)animated
                                                 pageName:_name
                                                   params:_params
                                                 uniqueId:self.uniqueIDString];
-//    如果当前不可见vc和engine所持有的vc一致。在FlutterVC在混合栈中是最后一张页面，如tab中的页面
-//     if (self == FLUTTER_VC)
-//     {
-//         [self surfaceUpdated:NO];
-//     }
     [super bridge_viewDidDisappear:animated];
 }