// Open the camera testing page, on which you can preview camera images and switch cameras.
- (IBAction)startCameraTest:(id)sender {
    // Start camera testing. `cameraPreview` is `NSView` on macOS or `UIView` on iOS.
    [self.trtcCloud startCameraDeviceTestInView:self.cameraPreview];
}

// Close the camera testing page.
- (void)windowWillClose:(NSNotification *)notification{
    // Stop camera testing.
    [self.trtcCloud stopCameraDeviceTest];
}


  // Sample code for mic testing
  -(IBAction)micTest:(id)sender {
    NSButton *btn = (NSButton *)sender;
    if (btn.state == 1) {
            // Start mic testing.
        __weak __typeof(self) wself = self;
        [self.trtcCloud startMicDeviceTest:500  testEcho:^(NSInteger volume) {
            dispatch_async(dispatch_get_main_queue(), ^{
                            // Refresh the mic volume bar.
                [wself _updateInputVolume:volume];
            });
        }];
        btn.title = @"Stop test";
    }
    else{
            // Stop mic testing.
        [self.trtcCloud stopMicDeviceTest];
        [self _updateInputVolume:0];
        btn.title = @"Start test";
    }
}


// Sample code for speaker testing
// Take an NSButton for example. In `xib`, set the title of the button in the on and off state to "Stop Test" and "Start Test".
- (IBAction)speakerTest:(NSButton *)btn {
    NSString *path = [[NSBundle mainBundle] pathForResource:@"test-32000-mono" ofType:@"mp3"];
    if (btn.state == NSControlStateValueOn) {
        // Click "Start Test".
        __weak __typeof(self) wself = self;
        [self.trtcEngine startSpeakerDeviceTest:path onVolumeChanged:^(NSInteger volume, BOOL playFinished) {
            // The subsequent steps involve the UI and need to be executed in the main queue.
            dispatch_async(dispatch_get_main_queue(), ^{
                // `_updateOutputVolume` means updating the speaker volume indicator on the UI.
                [wself _updateOutputVolume:volume];
                if (playFinished) {
                    // Set the button status to "Start Test" after playback is completed.
                    sender.state = NSControlStateValueOff;
                }
            });
        }];
    } else {
        // Click "Stop Test".
        [self.trtcEngine stopSpeakerDeviceTest];
        [self _updateOutputVolume:0];
    }
}

// Update the speaker volume indicator.
- (void)_updateOutputVolume:(NSInteger)volume {
    // `speakerVolumeMeter` is `NSLevelIndicator`.
    self.speakerVolumeMeter.doubleValue = volume / 255.0 * 10;
}