获取系统的右划返回手势

//手势谦让
[scrollView.panGestureRecognizer requireGestureRecognizerToFail:[self screenEdgePanGestureRecognizer]];

#pragma mark - 系统右划返回手势
- (UIScreenEdgePanGestureRecognizer *)screenEdgePanGestureRecognizer {
    UIScreenEdgePanGestureRecognizer *screenEdgePanGestureRecognizer = nil;
    if (self.navigationController.view.gestureRecognizers.count > 0) {
        for (UIGestureRecognizer *recognizer in self.navigationController.view.gestureRecognizers) {
            if ([recognizer isKindOfClass:[UIScreenEdgePanGestureRecognizer class]]) {
                screenEdgePanGestureRecognizer = (UIScreenEdgePanGestureRecognizer *)recognizer;
                break;
            }
        }
    }
    return screenEdgePanGestureRecognizer;
}