button or view?

button.mm

UIButton *baseView = [[UIButton alloc] initWithFrame:self.frame];
baseView.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.3];
[baseView addTarget:self action:@selector(dismissActionSheet) forControlEvents:UIControlEventTouchUpInside];

view.mm

UIView *baseView = [[UIView alloc] initWithFrame:self.frame];
baseView.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.3];
UITapGestureRecognizer* tapGesture  = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissActionSheet)];
tapGesture.delegate = self;
[baseView addGestureRecognizer:tapGesture];