Added iOS result containers for classification tasks

mediapipe/tasks/ios/components/containers/BUILD

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+# Copyright 2023 The MediaPipe Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+package(default_visibility = ["//mediapipe/tasks:internal"])
+
+licenses(["notice"])
+
+objc_library(
+    name = "MPPCategory",
+    srcs = ["sources/MPPCategory.m"],
+    hdrs = ["sources/MPPCategory.h"],
+)
+
+objc_library(
+    name = "MPPClassificationResult",
+    srcs = ["sources/MPPClassificationResult.m"],
+    hdrs = ["sources/MPPClassificationResult.h"],
+    deps = [
+        ":MPPCategory",
+    ],
+)

mediapipe/tasks/ios/components/containers/sources/MPPCategory.h

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+// Copyright 2023 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+  * Category is a util class that contains a label, its display name, a float value as score, and the
+  * index of the label in the corresponding label file. Typically it's used as the result of
+  * classification tasks.
+  **/
+NS_SWIFT_NAME(ClassificationCategory)
+@interface MPPCategory : NSObject
+
+/**
+  * The index of the label in the corresponding label file. Set to -1 if the index is
+  * not set.
+  **/
+@property(nonatomic, readonly) NSInteger index;
+
+/** Confidence score for this class . **/
+@property(nonatomic, readonly) float score;
+
+/** The label of this category object. **/
+@property(nonatomic, readonly, nullable) NSString *categoryName;
+
+/**
+  * The display name of the label, which may be translated for different locales. For example, a
+  * label, "apple", may be translated into Spanish for display purpose, so that the display name is
+  * "manzana".
+  **/
+@property(nonatomic, readonly, nullable) NSString *displayName;
+
+/**
+  * Initializes a new `MPPCategory` with the given index, score, category name and display name.
+  *
+  * @param index The index of the label in the corresponding label file.
+  * @param score The probability score of this label category.
+  * @param categoryName The label of this category object.
+  * @param displayName The display name of the label.
+  *
+  * @return An instance of `MPPCategory` initialized with the given index, score, category name and
+  * display name.
+  **/
+- (instancetype)initWithIndex:(NSInteger)index
+                        score:(float)score
+                 categoryName:(nullable NSString *)categoryName
+                  displayName:(nullable NSString *)displayName NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
++ (instancetype)new NS_UNAVAILABLE;
+
+@end
+
+NS_ASSUME_NONNULL_END

mediapipe/tasks/ios/components/containers/sources/MPPCategory.m

@@ -0,0 +1,33 @@
+// Copyright 2023 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "mediapipe/tasks/ios/components/containers/sources/MPPCategory.h"
+
+@implementation MPPCategory
+
+- (instancetype)initWithIndex:(NSInteger)index
+                        score:(float)score
+                 categoryName:(nullable NSString *)categoryName
+                  displayName:(nullable NSString *)displayName {
+  self = [super init];
+  if (self) {
+    _index = index;
+    _score = score;
+    _categoryName = categoryName;
+    _displayName = displayName;
+  }
+  return self;
+}
+
+@end

mediapipe/tasks/ios/components/containers/sources/MPPClassificationResult.h

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+// Copyright 2023 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <Foundation/Foundation.h>
+#import "mediapipe/tasks/ios/components/containers/sources/MPPCategory.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/** 
+ * Represents the list of classification for a given classifier head. Typically used as a result
+ * for classification tasks.
+ **/
+NS_SWIFT_NAME(Classifications)
+@interface MPPClassifications : NSObject
+
+/**
+ * The index of the classifier head these entries refer to. This is useful for multi-head models.
+ **/
+@property(nonatomic, readonly) NSInteger headIndex;
+
+/** The optional name of the classifier head, which is the corresponding tensor metadata name. **/
+@property(nonatomic, readonly, nullable) NSString *headName;
+
+/** An array of `MPPCategory` objects containing the predicted categories. **/
+@property(nonatomic, readonly) NSArray<MPPCategory *> *categories;
+
+/**
+ * Initializes a new `MPPClassifications` object with the given head index and array of categories.
+ * Head name is initialized to `nil`.
+ *
+ * @param headIndex The index of the classifier head.
+ * @param categories  An array of `MPPCategory` objects containing the predicted categories.
+ *
+ * @return An instance of `MPPClassifications` initialized with the given head index and
+ * array of categories.
+ **/
+- (instancetype)initWithHeadIndex:(NSInteger)headIndex
+                       categories:(NSArray<MPPCategory *> *)categories;
+
+/**
+ * Initializes a new `MPPClassifications` with the given head index, head name and array of
+ * categories.
+ *
+ * @param headIndex The index of the classifier head.
+ * @param headName The name of the classifier head, which is the corresponding tensor metadata
+ * name.
+ * @param categories An array of `MPPCategory` objects containing the predicted categories.
+ *
+ * @return An object of `MPPClassifications` initialized with the given head index, head name and
+ * array of categories.
+ **/
+- (instancetype)initWithHeadIndex:(NSInteger)headIndex
+                         headName:(nullable NSString *)headName
+                       categories:(NSArray<MPPCategory *> *)categories NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
++ (instancetype)new NS_UNAVAILABLE;                       
+
+@end
+
+/**
+ * Represents the classification results of a model. Typically used as a result for classification
+ * tasks.
+ **/
+NS_SWIFT_NAME(ClassificationResult)
+@interface MPPClassificationResult : NSObject
+
+/** 
+ * An Array of `MPPClassifications` objects containing the predicted categories for each head of
+ * the model. 
+ **/
+@property(nonatomic, readonly) NSArray<MPPClassifications *> *classifications;
+
+/** 
+ * The optional timestamp (in milliseconds) of the start of the chunk of data corresponding to
+ * these results. If it is set to the value -1, it signifies the absence of a timestamp. This is
+ * only used for classification on time series (e.g. audio classification). In these use cases, the
+ * amount of data to process might exceed the maximum size that the model can process: to solve
+ * this, the input data is split into multiple chunks starting at different timestamps.
+ **/
+@property(nonatomic, readonly) NSInteger timestampMs;
+
+/**
+ * Initializes a new `MPPClassificationResult` with the given array of classifications and time
+ * stamp (in milliseconds).
+ *
+ * @param classifications An Array of `MPPClassifications` objects containing the predicted
+ * categories for each head of the model.
+ * @param timestampMs The timestamp (in milliseconds) of the start of the chunk of data
+ * corresponding to these results.
+ *
+ * @return An instance of `MPPClassificationResult` initialized with the given array of
+ * classifications and timestampMs.
+ **/
+- (instancetype)initWithClassifications:(NSArray<MPPClassifications *> *)classifications
+                            timestampMs:(NSInteger)timestampMs NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
++ (instancetype)new NS_UNAVAILABLE;
+
+@end
+
+NS_ASSUME_NONNULL_END

mediapipe/tasks/ios/components/containers/sources/MPPClassificationResult.m

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+// Copyright 2023 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "mediapipe/tasks/ios/components/containers/sources/MPPClassificationResult.h"
+
+@implementation MPPClassifications
+
+- (instancetype)initWithHeadIndex:(NSInteger)headIndex
+                         headName:(nullable NSString *)headName
+                       categories:(NSArray<MPPCategory *> *)categories {
+  self = [super init];
+  if (self) {
+    _headIndex = headIndex;
+    _headName = headName;
+    _categories = categories;
+  }
+  return self;
+}
+
+- (instancetype)initWithHeadIndex:(NSInteger)headIndex
+                       categories:(NSArray<MPPCategory *> *)categories {
+  return [self initWithHeadIndex:headIndex headName:nil categories:categories];
+}
+
+@end
+
+@implementation MPPClassificationResult
+
+- (instancetype)initWithClassifications:(NSArray<MPPClassifications *> *)classifications
+                            timestampMs:(NSInteger)timestampMs {
+  self = [super init];
+  if (self) {
+    _classifications = classifications;
+    _timestampMs = timestampMs;
+  }
+
+  return self;
+}
+
+@end