Expose media constraint string constants as ObjC NSStrings

webrtc/sdk/objc/Framework/Classes/RTCMediaConstraints.mm

 /*
  *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #import "RTCMediaConstraints+Private.h"
 
 #import "NSString+StdString.h"
 
 #include <memory>
 
+NSString * const kRTCMediaConstraintsMinAspectRatio =
+    @(webrtc::MediaConstraintsInterface::kMinAspectRatio);
+NSString * const kRTCMediaConstraintsMaxAspectRatio =
+    @(webrtc::MediaConstraintsInterface::kMaxAspectRatio);
+NSString * const kRTCMediaConstraintsMinWidth =
+    @(webrtc::MediaConstraintsInterface::kMinWidth);
+NSString * const kRTCMediaConstraintsMaxWidth =
+    @(webrtc::MediaConstraintsInterface::kMaxWidth);
+NSString * const kRTCMediaConstraintsMinHeight =
+    @(webrtc::MediaConstraintsInterface::kMinHeight);
+NSString * const kRTCMediaConstraintsMaxHeight =
+    @(webrtc::MediaConstraintsInterface::kMaxHeight);
+NSString * const kRTCMediaConstraintsMinFrameRate =
+    @(webrtc::MediaConstraintsInterface::kMinFrameRate);
+NSString * const kRTCMediaConstraintsMaxFrameRate =
+    @(webrtc::MediaConstraintsInterface::kMaxFrameRate);
+
 namespace webrtc {
 
 MediaConstraints::~MediaConstraints() {}
 
 MediaConstraints::MediaConstraints() {}
 
 MediaConstraints::MediaConstraints(
     const MediaConstraintsInterface::Constraints& mandatory,
     const MediaConstraintsInterface::Constraints& optional)
     : mandatory_(mandatory), optional_(optional) {}
@@ skipping 58 matching lines @@
     NSString *value = [constraints objectForKey:key];
     NSAssert([value isKindOfClass:[NSString class]],
              @"%@ is not an NSString.", value);
     nativeConstraints.push_back(webrtc::MediaConstraintsInterface::Constraint(
         key.stdString, value.stdString));
   }
   return nativeConstraints;
 }
 
 @end