iOS Programming: The Big Nerd Ranch Guide

Multiple Gesture Recognizers

Let’s add another gesture recognizer that allows the user to select a line. (Later, a user will be able to delete the selected line.) You will install another UITapGestureRecognizer on the BNRDrawView that only requires one tap.

In BNRDrawView.m, modify initWithFrame:.

        [self addGestureRecognizer:doubleTapRecognizer];
        
        UITapGestureRecognizer *tapRecognizer =
            [[UITapGestureRecognizer alloc] initWithTarget:self
                                                    action:@selector(tap:)];
        tapRecognizer.delaysTouchesBegan = YES;
        [self addGestureRecognizer:tapRecognizer];
    }

    return self;
}

Now, implement tap: to log the tap to the console in BNRDrawView.m.

- (void)tap:(UIGestureRecognizer *)gr
{
    NSLog(@"Recognized tap");
}

Build and run the application. ...