Programmatically scroll a UIScrollView

Question

I have a UIScrollView which has several views. When a user flicks their finger, the view scrolls to the right or left depending on the direction of the finger flick. Basically my code works in a way similar to the iPhone photo app. Now, is there a way that I can programmatically do the same thing so that I end up with a slideshow that runs on its own with a click of a button and a configurable pause between each scroll?

How do you really do slideshows with UIScrollView?

Solution 1

You can scroll to some point in a scroll view with one of the following statements in Objective-C

[scrollView setContentOffset:CGPointMake(x, y) animated:YES];

or Swift

scrollView.setContentOffset(CGPoint(x: x, y: y), animated: true)

See the guide "Scrolling the Scroll View Content" from Apple as well.

To do slideshows with UIScrollView, you arrange all images in the scroll view, set up a repeated timer, then -setContentOffset:animated: when the timer fires.

But a more efficient approach is to use 2 image views and swap them using transitions or simply switching places when the timer fires. See iPhone Image slideshow for details.

Solution 2

If you want control over the duration and style of the animation, you can do:

[UIView animateWithDuration:2.0f delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
    scrollView.contentOffset = CGPointMake(x, y);
} completion:NULL];

Adjust the duration (2.0f) and options (UIViewAnimationOptionCurveLinear) to taste!

Solution 3

I'm amazed that this topic is 9 years old and the actual straightforward answer is not here!

What you're looking for is scrollRectToVisible(_:animated:).

Example:

extension SignUpView: UITextFieldDelegate {
    func textFieldDidBeginEditing(_ textField: UITextField) {
        scrollView.scrollRectToVisible(textField.frame, animated: true)
    }
}

What it does is exactly what you need, and it's far better than hacky contentOffset

This method scrolls the content view so that the area defined by rect is just visible inside the scroll view. If the area is already visible, the method does nothing.

From: https://developer.apple.com/documentation/uikit/uiscrollview/1619439-scrollrecttovisible

Solution 4

Another way is

scrollView.contentOffset = CGPointMake(x,y);

Solution 5

With Animation in Swift

scrollView.setContentOffset(CGPointMake(x, y), animated: true)

View more solutions

Comments

[climbon]

Cool. Yes, I did find that setContentOffset works but really wanted this to happen in animated way. 'animated:YES' did the trick.

[Evan Mulawski]

This is exactly the same as the accepted answer. And CGPoint should be CGPointMake.

[Giovanni]

Just complementing the answer, to move horizontally to the next "page" in UIScrollView (assuming you are coding for iPhone), for the x parameter use (myScrollView.contentOffset.x +320).

[DD_]

@niraj thanks dude...in (myScrollView.contentOffset.x +320) lies the key!

[Chris]

Correct me if I'm wrong, but UIScrollView's contentOffset: will offset the contentSize as well, which may not be desirable. To only scroll, you may want to use scrollRectToVisible:.

[user1781290]

Please consider adding some text to your answer, not only pure code

[quemeful]

I like simple answers like this one.

[Arnold]

Do no use C helper functions like CGPointMake in Swift. Simply build a Swift struct directly: CGPoint(x: 0, y: 44)

[Rickster]

Actually, this is not the same as the accepted answer. The accepted answer has an option of animated, which some apps might want to have set to YES.

[Abhishek Thapliyal]

[scrollView scrollRectToVisible:CGRectMake(x, y, width, height), animated:YES]; when i'm adding this it is slightly scrolled upwards initially. Can you give me a fix @kennytm ?

[Abdurakhmon]

good solution, but contentOffset gives more control over where exactly you want to scroll