text: /*
   *  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 <Foundation/Foundation.h>
  
  #import "RTCMacros.h"
  
  NS_ASSUME_NONNULL_BEGIN
  
  RTC_OBJC_EXPORT
  @protocol RTC_OBJC_TYPE
  (RTCDtmfSender)<NSObject>
  
      /**
       * Returns true if this RTCDtmfSender is capable of sending DTMF. Otherwise
       * returns false. To be able to send DTMF, the associated RTCRtpSender must be
       * able to send packets, and a "telephone-event" codec must be negotiated.
       */
      @property(nonatomic, readonly) BOOL canInsertDtmf;
  
  /**
   * Queues a task that sends the DTMF tones. The tones parameter is treated
   * as a series of characters. The characters 0 through 9, A through D, #, and *
   * generate the associated DTMF tones. The characters a to d are equivalent
   * to A to D. The character ',' indicates a delay of 2 seconds before
   * processing the next character in the tones parameter.
   *
   * Unrecognized characters are ignored.
   *
   * @param duration The parameter indicates the duration to use for each
   * character passed in the tones parameter. The duration cannot be more
   * than 6000 or less than 70 ms.
   *
   * @param interToneGap The parameter indicates the gap between tones.
   * This parameter must be at least 50 ms but should be as short as
   * possible.
   *
   * If InsertDtmf is called on the same object while an existing task for this
   * object to generate DTMF is still running, the previous task is canceled.
   * Returns true on success and false on failure.
   */
  - (BOOL)insertDtmf:(nonnull NSString *)tones
            duration:(NSTimeInterval)duration
        interToneGap:(NSTimeInterval)interToneGap;
  
  /** The tones remaining to be played out */
  - (nonnull NSString *)remainingTones;
  
  /**
   * The current tone duration value. This value will be the value last set via the
   * insertDtmf method, or the default value of 100 ms if insertDtmf was never called.
   */
  - (NSTimeInterval)duration;
  
  /**
   * The current value of the between-tone gap. This value will be the value last set
   * via the insertDtmf() method, or the default value of 50 ms if insertDtmf() was never
   * called.
   */
  - (NSTimeInterval)interToneGap;
  
  @end
  
  NS_ASSUME_NONNULL_END
  