iOS: Add new RTCVideoSource interface

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoCapturer.h

+/*
+ *  Copyright 2017 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 <WebRTC/RTCVideoFrame.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+RTC_EXPORT
+
+@protocol RTCVideoCapturerDelegate;
+
+@interface RTCVideoCapturer : NSObject
+- (instancetype)initWithDelegate:(__weak id<RTCVideoCapturerDelegate>)delegate;

[daniela-webrtc, 2017/03/20 14:23:10]

We don't need to enforce invokers of the method to pass weak reference as we're
gonna "waekify" it ourselves.

[magjed_webrtc, 2017/03/27 12:35:11]

Done.

+@property(nonatomic, readonly) id<RTCVideoCapturerDelegate> delegate;

[daniela-webrtc, 2017/03/20 14:23:10]

Do we need to expose the delegate as property here? I think not as it's injected
in the initializer.

[daniela-webrtc, 2017/03/20 15:18:30]

Ah just saw that we need it for subclassing. 
In that case
@property (nonatomic, readonly, weak) id<RTCVideoCapturerDelegate> delegate;

Default is strong and we don't want that.

[magjed_webrtc, 2017/03/27 12:35:11]

Done.

+@end
+
+@protocol RTCVideoCapturerDelegate

[daniela-webrtc, 2017/03/20 14:23:10]

Nit: It's common to declare the protocol on top of the class like so

@class RTCVideoCapturer;

@protocol RTCVideoCapturerDelegate
...
@end

@interface RTCVideoCapturer : NSObject
...
@end

[magjed_webrtc, 2017/03/27 12:35:11]

Done.

+- (void)capturer:(RTCVideoCapturer*)capturer

[daniela-webrtc, 2017/03/20 14:23:10]

Nit: RTCVideoCapturer* -> RTCVideoCapturer *

[magjed_webrtc, 2017/03/27 12:35:11]

Done.

+    didCaptureVideoFrame:(RTCVideoFrame*)frame;

[daniela-webrtc, 2017/03/20 14:23:10]

Same spacing comment

[magjed_webrtc, 2017/03/27 12:35:11]

Done.

+@end
+
+NS_ASSUME_NONNULL_END