Detect UITextView scroll location

Question

I am trying to implement a form of a Terms & Conditions page where the "Proceed" button is only enabled once the user has scrolled to the bottom of a UITextView. So far I have set my class as a UIScrollView delegate & have implemented the method below:

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    NSLog(@"Checking if at bottom of UITextView");
    CGPoint bottomOffset = CGPointMake(0,self.warningTextView.frame.size.height);
    //if ([[self.warningTextView contentOffset] isEqualTO:bottomOffset])
    {
    }    
}

I have commented the if statement because I am not sure how to check if the UITextView is at the bottom.

Retrograde

Answer 1

UITextView is a UIScrollView subclass. Therefore the UIScrollView delegate method you are using is also available when using UITextView.

Instead of using scrollViewDidEndDecelerating, you should use scrollViewDidScroll, as the scrollview may stop scrolling without deceleration.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if (scrollView.contentOffset.y >= scrollView.contentSize.height - scrollView.frame.size.height)
    {
        NSLog(@"at bottom");
    }
}

Cordeliacordelie

Thanks Owen, I will try this out this evening & update if successful (or not)! James Question: you mention scrollView in your example - does it matter if I reference my UITextView.contentOffSet.y etc? – Retrograde

the scrollView you concerned is the variable name, you can call it anything you like as long as you change the one in the method name too. For example you can call it textView, and change the method name to - (void)scrollViewDidScroll:(UIScrollView *)textView. Or, you can reference your UITextView directly, and change the if line to if (self.warningTextView.contentOffset.y >= self.warningTextView.contentSize.height - self.warningTextView.frame.size.height). – Cordeliacordelie

Answer 2

A Swift version for this question:

func scrollViewDidScroll(_ scrollView: UIScrollView) {

    if scrollView.contentOffset.y >= scrollView.contentSize.height - scrollView.frame.size.height {

        print( "View scrolled to the bottom" )

    }
}

Terle

Answer 3

This should solve it. It works. I am using it.

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView 
{
    float bottomEdge = scrollView.contentOffset.y + scrollView.frame.size.height;
    if (bottomEdge >= scrollView.contentSize.height) 
    {
        // we are at the end
    }
}

Lali

Good approach. When working with float-values though, I would add an error margin. – Aruwimi