适配v1.12.13. 同时解决多次surfaceUpdated问题，通过这个解法，每次显示只需要调用一次。但该解法编译后动画时候会abort，不知道是否有关系——之前也出现过，但非必现

ios/Classes/1.5/FLB2FlutterViewContainer.m

@@ -32,6 +32,37 @@
 #define FLUTTER_VIEW FLUTTER_APP.flutterViewController.view
 #define FLUTTER_VC FLUTTER_APP.flutterViewController
 
+@interface FlutterViewController (bridgeToviewDidDisappear)
+- (void)flushOngoingTouches;
+- (void)bridge_viewDidDisappear:(BOOL)animated;
+- (void)bridge_viewWillAppear:(BOOL)animated;
+@end
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wincomplete-implementation"
+@implementation FlutterViewController (bridgeToviewDidDisappear)
+- (void)bridge_viewDidDisappear:(BOOL)animated{
+//    TRACE_EVENT0("flutter", "viewDidDisappear");
+    [self flushOngoingTouches];
+
+    [super viewDidDisappear:animated];
+}
+
+- (void)bridge_viewWillAppear:(BOOL)animated{
+//    TRACE_EVENT0("flutter", "viewWillAppear");
+
+//    if (_engineNeedsLaunch) {
+//      [_engine.get() launchEngine:nil libraryURI:nil];
+//      [_engine.get() setViewController:self];
+//      _engineNeedsLaunch = NO;
+//    }
+    [FLUTTER_APP inactive];
+    
+    [super viewWillAppear:animated];
+}
+@end
+#pragma pop
+
 @interface FLB2FlutterViewContainer  ()
 @property (nonatomic,strong,readwrite) NSDictionary *params;
 @property (nonatomic,assign) long long identifier;
@@ -52,6 +83,13 @@
     return self;
 }
 
+- (instancetype)initWithProject:(FlutterDartProject*)projectOrNil
+                        nibName:(NSString*)nibNameOrNil
+                         bundle:(NSBundle*)nibBundleOrNil {
+    NSAssert(NO, @"unsupported init method!");
+    return nil;
+}
+
 - (instancetype)initWithCoder:(NSCoder *)aDecoder{
     if (self = [super initWithCoder: aDecoder]) {
         NSAssert(NO, @"unsupported init method!");
@@ -159,7 +197,9 @@ static NSUInteger kInstanceCounter = 0;
 {
     //For new page we should attach flutter view in view will appear
     //for better performance.
- 
+
+    [self attatchFlutterEngine];
+
     [BoostMessageChannel willShowPageContainer:^(NSNumber *result) {}
                                             pageName:_name
                                               params:_params
@@ -171,7 +211,8 @@ static NSUInteger kInstanceCounter = 0;
         [FlutterBoostPlugin2 sharedInstance].fParams = _params;
     }
     
-    [super viewWillAppear:animated];
+    [super bridge_viewWillAppear:animated];
+    [self.view setNeedsLayout];//TODO:通过param来设定
 }
 
 - (void)viewDidAppear:(BOOL)animated
@@ -185,8 +226,9 @@ static NSUInteger kInstanceCounter = 0;
                                            pageName:_name
                                              params:_params
                                            uniqueId:self.uniqueIDString];
-    //NOTES：务必在show之后再update，否则有闪烁
+    //NOTES：务必在show之后再update，否则有闪烁; 或导致侧滑返回时上一个页面会和top页面内容一样
     [self surfaceUpdated:YES];
+
     [super viewDidAppear:animated];
 }
 
@@ -198,12 +240,6 @@ static NSUInteger kInstanceCounter = 0;
                                                  uniqueId:self.uniqueIDString];
     [[[UIApplication sharedApplication] keyWindow] endEditing:YES];
     [super viewWillDisappear:animated];
-    
-    //NOTES：因为UIViewController在present view后dismiss其页面的view disappear会发生在下一个页面view appear之后，从而让当前engine持有的vc inactive，此处可驱使其重新resume
-    if (![self.uniqueIDString isEqualToString:[(FLB2FlutterViewContainer*)FLUTTER_VC uniqueIDString]])
-    {
-        [FLUTTER_APP resume];
-    }
 }
 
 
@@ -213,15 +249,8 @@ static NSUInteger kInstanceCounter = 0;
                                                 pageName:_name
                                                   params:_params
                                                 uniqueId:self.uniqueIDString];
-    [super viewDidDisappear:animated];
-    
-    //NOTES:因为UIViewController在present view后dismiss其页面的view disappear会发生在下一个页面view appear之后，导致当前engine持有的VC被surfaceUpdate(NO)，从而销毁底层的raster。此处是考虑到这种情形，重建surface
-    if (FLUTTER_VC.beingPresented || self.beingDismissed || ![self.uniqueIDString isEqualToString:[(FLB2FlutterViewContainer*)FLUTTER_VC uniqueIDString]])
-    {
-        [FLUTTER_APP resume];
-        [(FLB2FlutterViewContainer*)FLUTTER_VC surfaceUpdated:YES];
-    }
     
+    [super bridge_viewDidDisappear:animated];
 }
 
 - (void)installSplashScreenViewIfNecessary {