Deslizar hacia la derecha SOLAMENTE después de al menos un deslizamiento hacia la izquierda

I am using left and right swipe for 'next image' and 'previous image'. On startup of the app I want to disable right swipe(previous) until at least one left swipe - is there any obvious way to do that?

preguntado el 28 de mayo de 14 a las 11:05

What did you try? Did you search Google before coming here? See ¿Cómo hago una buena pregunta? -

I have searched around yes, but find it rather difficult what exactly to search for. Have triends things such as: objective c +'disable function until' 'disable function conditional' etc -

I found a solution by moving the code where the function for right swipe is defined into the action of the left swipe - so that the right swipe is not defined until the first left swipe has been done by the user -

This method is not very clean, please look at my answer. -

1 Respuestas

You can create a simple method to handle swipes from all UISwipeGestureRecognizer instances. This method will enable/disable the gesture recognizers by itself.

Considering that you have two recognizers, namely

UISwipeGestureRecognizer *swipeRight;
UISwipeGestureRecognizer *swipeLeft;

And an array of images to be shown

NSArray *arrImages;

You will also need to maintain a global ivar 

NSInteger currIndex; //To maintain the index

Both should have the same method as their selector, which is as follows:

-(void)handleSwipeFrom:(UISwipeGestureRecognizer*)recognizer
{
    NSInteger newIndex = currIndex;

    if ([recognizer isEqual: swipeLeft])
    {
        newIndex ++;
    }
    else if ([recognizer isEqual: swipeRight])
    {
        newIndex --;
    }

    if (newIndex >= 0 && newIndex <= ([arrImages count] - 1))
        [self showImageAtIndex:newIndex];

}

The showImageAtIndex: method can handle the rest as follows:

-(void) showImageAtIndex: (NSInteger)index
{
    if (index == 0)
    {
        [swipeRight setEnabled:NO];
    }
    else
    {
        [swipeRight setEnabled:YES];
    }

    if (index == ([arrImages count] - 1))
    {
        [swipeLeft setEnabled:NO];
    }
    else
    {
        [swipeLeft setEnabled:YES];
    }

    currIndex = index;


//Show image at currIndex here

}

For this to work perfectly, you need to instantiate currIndex and call showImageAtIndex in viewDidLoad:

currIndex = 0;
[self showImageAtIndex: currIndex];

contestado el 28 de mayo de 14 a las 12:05

No es la respuesta que estás buscando? Examinar otras preguntas etiquetadas or haz tu propia pregunta.