run predictions on background queues

Author: glaszig

src/coreml/MLModel+Compat.m

@@ -10,7 +10,10 @@ - (void) predictionFromFeatures:(id<MLFeatureProvider>) input
     [NSOperationQueue.mainQueue addOperationWithBlock:^{
         NSError *error = nil;
         id<MLFeatureProvider> prediction = [self predictionFromFeatures:input error:&error];
-        completionHandler(prediction, error);
+
+        [NSOperationQueue.mainQueue addOperationWithBlock:^{
+            completionHandler(prediction, error);
+        }];
     }];
 }
 
@@ -20,7 +23,10 @@ - (void) predictionFromFeatures:(id<MLFeatureProvider>) input
     [NSOperationQueue.mainQueue addOperationWithBlock:^{
         NSError *error = nil;
         id<MLFeatureProvider> prediction = [self predictionFromFeatures:input options:options error:&error];
-        completionHandler(prediction, error);
+
+        [NSOperationQueue.mainQueue addOperationWithBlock:^{
+            completionHandler(prediction, error);
+        }];
     }];
 }