Fix cache problems.

ios/Classes/Container/FLBFlutterViewContainer.m

@@ -39,6 +39,7 @@
 @property (nonatomic,strong,readwrite) NSDictionary *params;
 @property (nonatomic,strong) UIImageView *screenShotView;
 @property (nonatomic,assign) long long identifier;
+@property (nonatomic,assign) BOOL interactiveGestureActive;
 @end
 
 @implementation FLBFlutterViewContainer
@@ -241,6 +242,8 @@ static NSUInteger kInstanceCounter = 0;
             [self.view insertSubview:FLUTTER_VIEW
                              atIndex:0];
         }
+    }else{
+        
     }
     
     return self.screenShotView.image != nil;
@@ -262,8 +265,8 @@ static NSUInteger kInstanceCounter = 0;
     
     [self clearCurrentScreenShotImage];
     
-    //Remove obsolete screenshot.
-    [FLBStackCache.sharedInstance remove:self.uniqueIDString];
+    //Invalidate obsolete screenshot.
+    [FLBStackCache.sharedInstance invalidate:self.uniqueIDString];
 }
 
 #pragma mark - Life circle methods
@@ -276,6 +279,10 @@ static NSUInteger kInstanceCounter = 0;
 
 - (void)viewWillAppear:(BOOL)animated
 {
+    if(self.navigationController.interactivePopGestureRecognizer.state == UIGestureRecognizerStateBegan){
+        self.interactiveGestureActive = true;
+    }
+    
     [[FLBFlutterApplication sharedApplication] resume];
     //For new page we should attach flutter view in view will appear
     //for better performance.
@@ -319,17 +326,25 @@ static NSUInteger kInstanceCounter = 0;
     dispatch_after(dispatch_time(DISPATCH_TIME_NOW,
                                  (int64_t)(2 * NSEC_PER_SEC)),
                    dispatch_get_main_queue(),^{
-                       [weakSelf showFlutterView];
+                       if (weakSelf.isViewLoaded && weakSelf.view.window) {
+                           // viewController is visible
+                            [weakSelf showFlutterView];
+                       }
                    });
+    
+    self.interactiveGestureActive = NO;
 }
 
 - (void)viewWillDisappear:(BOOL)animated
 {
     //is top.
     if([FLUTTER_APP isTop:self.uniqueIDString]
-       && self.navigationController.interactivePopGestureRecognizer.state != UIGestureRecognizerStateBegan){
+       && self.navigationController.interactivePopGestureRecognizer.state != UIGestureRecognizerStateBegan
+       && !self.interactiveGestureActive){
         [self saveScreenShot];
     }
+    
+    self.interactiveGestureActive = NO;
    
     self.screenShotView.image = [self getSavedScreenShot];
     if(self.screenShotView.image){
@@ -355,6 +370,7 @@ static NSUInteger kInstanceCounter = 0;
     [super viewDidDisappear:animated];
 
     [FLUTTER_APP inactive];
+    self.interactiveGestureActive = NO;
 }
 
 #pragma mark - FLBViewControllerResultHandler

ios/Classes/Support/Cache/FLBStackCache.h

@@ -41,6 +41,12 @@
                      cache:(FLBStackCache *)cache
                  completion:(void (^)(NSError *err ,id<FLBStackCacheObject>))completion;
 
+- (BOOL)removeCachedFileWithKey:(NSString *)key
+                          queue:(dispatch_queue_t)queue
+                          cache:(FLBStackCache *)cache
+                     completion:(void (^)(NSError *, NSString *))completion;
+
+
 @end
 
 
@@ -56,6 +62,7 @@
 #pragma mark - basic operations.
 - (void)pushObject:(id<FLBStackCacheObject>)obj key:(NSString *)key;
 - (id<FLBStackCacheObject>)remove:(NSString *)key;
+- (void)invalidate:(NSString *)key;
 - (BOOL)empty;
 - (void)clear;
 - (id<FLBStackCacheObject>)objectForKey:(NSString *)key;

ios/Classes/Support/Cache/FLBStackCache.m

@@ -84,7 +84,7 @@
         return;
     }
     
-    if(!_inMemoryObjectsMap[key]){
+    if(![_keyStack containsObject:key]){
         [_keyStack addObject:key];
     }else{
         //return;
@@ -136,6 +136,23 @@
     return ob;
 }
 
+- (void)invalidate:(NSString *)key
+{
+    if(!key || [self empty]) return;
+    
+    if(![_keyStack containsObject:key]) return;
+    
+    id<FLBStackCacheObject> ob = _inMemoryObjectsMap[key];
+    [ob removeCachedFileWithKey:key
+                          queue:_queueIO
+                          cache:self
+                     completion:^(NSError *err, NSString *k) {
+    }];
+    [_inMemoryObjectsMap removeObjectForKey:key];
+    
+    [self preloadIfNeeded];
+}
+
 - (void)preloadIfNeeded
 {
     for(NSString *key in self.keyStack.reverseObjectEnumerator){

ios/Classes/Support/Cache/FLBStackCacheObjectImg.m

@@ -91,4 +91,26 @@
     return YES;
 }
 
+- (BOOL)removeCachedFileWithKey:(NSString *)key
+                          queue:(dispatch_queue_t)queue
+                          cache:(FLBStackCache *)cache
+                     completion:(void (^)(NSError *, NSString *))completion
+{
+    if(!key){
+        return NO;
+    }
+    
+    dispatch_async(queue, ^{
+        NSString *filePath = [FLBStackCacheObjectImg filePathByKey:key dirPath:cache.cacheDir];
+        NSError *err = nil;
+        [NSFileManager.defaultManager removeItemAtPath:filePath error:&err];
+        if (completion) {
+            completion(err,key);
+        }
+    });
+    
+    return YES;
+}
+
+
 @end

pubspec.yaml

 name: flutter_boost
 description: A next-generation Flutter-Native hybrid solution. FlutterBoost is a Flutter plugin which enables hybrid integration of Flutter for your existing native apps with minimum efforts.
-version: 0.0.39
+version: 0.0.407
 author: Alibaba Xianyu
 homepage: https://github.com/alibaba/flutter_boost