Added method to create unique dispatch queue names in MPPVisionTaskRunner

mediapipe/tasks/ios/common/utils/sources/NSString+Helpers.h

@@ -24,6 +24,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (NSString *)stringWithCppString:(std::string)text;
 
++ (NSString *)uuidString;
 @end
 
 NS_ASSUME_NONNULL_END

mediapipe/tasks/ios/common/utils/sources/NSString+Helpers.mm

@@ -24,4 +24,8 @@
   return [NSString stringWithCString:text.c_str() encoding:[NSString defaultCStringEncoding]];
 }
 
++ (NSString *)uuidString{
+  return [[NSUUID UUID] UUIDString];
+}
+
 @end

mediapipe/tasks/ios/vision/core/BUILD

@@ -58,6 +58,7 @@ objc_library(
         "//mediapipe/framework/formats:rect_cc_proto",
         "//mediapipe/tasks/ios/common:MPPCommon",
         "//mediapipe/tasks/ios/common/utils:MPPCommonUtils",
+        "//mediapipe/tasks/ios/common/utils:NSStringHelpers",
         "//mediapipe/tasks/ios/core:MPPTaskRunner",
         "//third_party/apple_frameworks:UIKit",
         "@com_google_absl//absl/status:statusor",

mediapipe/tasks/ios/vision/core/sources/MPPVisionTaskRunner.h

@@ -141,6 +141,20 @@ NS_ASSUME_NONNULL_BEGIN
                                   (mediapipe::tasks::core::PacketsCallback)packetsCallback
                                         error:(NSError **)error NS_UNAVAILABLE;
 
+/**
+ * This method returns a unique dispatch queue name by adding the given suffix and a `UUID` to the
+ * pre-defined queue name prefix for vision tasks. The vision tasks can use this method to get
+ * unique dispatch queue names which are consistent with other vision tasks.
+ * Dispatch queue names need not be unique, but for easy debugging we ensure that the queue names
+ * are unique.
+ *
+ * @param suffix A suffix that identifies a dispatch queue's functionality.
+ *
+ * @return A unique dispatch queue name by adding the given suffix and a `UUID` to the pre-defined
+ * queue name prefix for vision tasks.
+ */
++ (const char *)uniqueDispatchQueueNameWithSuffix:(NSString *)suffix;
+
 - (instancetype)init NS_UNAVAILABLE;
 
 + (instancetype)new NS_UNAVAILABLE;

mediapipe/tasks/ios/vision/core/sources/MPPVisionTaskRunner.mm

@@ -16,6 +16,7 @@
 
 #import "mediapipe/tasks/ios/common/sources/MPPCommon.h"
 #import "mediapipe/tasks/ios/common/utils/sources/MPPCommonUtils.h"
+#import "mediapipe/tasks/ios/common/utils/sources/NSString+Helpers.h"
 
 #include "absl/status/statusor.h"
 
@@ -37,6 +38,8 @@ static const NSInteger kMPPOrientationDegreesDown = -180;
 /** Rotation degrees for a 90 degree rotation to the left. */
 static const NSInteger kMPPOrientationDegreesLeft = -270;
 
+static NSString *const kTaskPrefix = @"com.mediapipe.tasks.vision";
+
 @interface MPPVisionTaskRunner () {
   MPPRunningMode _runningMode;
 }
@@ -54,18 +57,21 @@ static const NSInteger kMPPOrientationDegreesLeft = -270;
       if (packetsCallback) {
         [MPPCommonUtils createCustomError:error
                                  withCode:MPPTasksErrorCodeInvalidArgumentError
-                              description:@"The vision task is in image or video mode, a "
+                              description:@"The vision task is in image or video mode. The "
-                                          @"user-defined result callback should not be provided."];
+                                          @"delegate must not be set in the task's options."];
         return nil;
       }
       break;
     }
     case MPPRunningModeLiveStream: {
       if (!packetsCallback) {
-        [MPPCommonUtils createCustomError:error
+        [MPPCommonUtils
+            createCustomError:error
                      withCode:MPPTasksErrorCodeInvalidArgumentError
-                              description:@"The vision task is in live stream mode, a user-defined "
+                  description:
-                                          @"result callback must be provided."];
+                      @"The vision task is in live stream mode. An object must be set as the "
+                      @"delegate of the task in its options to ensure asynchronous delivery of "
+                      @"results."];
         return nil;
       }
       break;
@@ -197,4 +203,9 @@ static const NSInteger kMPPOrientationDegreesLeft = -270;
   return [self sendPacketMap:packetMap error:error];
 }
 
++ (const char *)uniqueDispatchQueueNameWithSuffix:(NSString *)suffix {
+  return [NSString stringWithFormat:@"%@.%@_%@", kTaskPrefix, suffix, [NSString uuidString]]
+      .UTF8String;
+}
+
 @end