How to make a UIScrollView auto scroll when a UITe

问题:

I've seen posts around here that suggest that UIScrollViews should automatically scroll if a subview UITextField becomes the first responder; however, I can't figure out how to get this to work.

What I have is a UIViewController that has a UIScrollView and within the UIScrollView there are multiple textfields.

I know how to do this manually if necessary; however, from what I've been reading, it seems possible to have it autoscroll. Help please.

回答1:

I hope this example will help you You can scroll to any point by this code.

scrollView.contentOffset = CGPointMake(0,0);

So if you have textfield, it must have some x,y position on view, so you can use

CGPoint point = textfield.frame.origin ;
scrollView.contentOffset = point 

This should do the trick,

But if you don't know when to call this code, so you should learn UITextFieldDelegate methods

Implement this method in your code

- (void)textFieldDidBeginEditing:(UITextField *)textField {
// Place Scroll Code here
}

I hope you know how to use delegate methods.

回答2:

I know this question has already been answered, but I thought I would share the code combination that I used from @Adeel and @Basil answer, as it seems to work perfectly for me on iOS 9.

-(void)textFieldDidBeginEditing:(UITextField *)textField {

    // Scroll to the text field so that it is
    // not hidden by the keyboard during editing.
    [scroll setContentOffset:CGPointMake(0, (textField.superview.frame.origin.y + (textField.frame.origin.y))) animated:YES];
}

-(void)textFieldDidEndEditing:(UITextField *)textField {

    // Remove any content offset from the scroll
    // view otherwise the scroll view will look odd.
    [scroll setContentOffset:CGPointMake(0, 0) animated:YES];
}

I also used the animated method, it makes for a much smoother transition.

回答3:

There is nothing you have to do manually. It is the default behavior. There are two possibilities as to why you are not seeing the behavior

1. The most likely reason is that the keyboard is covering your UITextField. See below for solution
2. The other possibility is that you have another UIScrollView somewhere in the view hierarchy between the UITextField and the UIScrollView that you want to auto scroll. This is less likely but can still cause problems.

For #1, you want to implement something similar to Apple's recommendations for Moving Content That Is Located Under the Keyboard. Note that the code provided by Apple does not account for rotation. For improvements on their code, check out this blog post's implementation of the keyboardDidShow method that properly translates the keyboard's frame using the window.

回答4:

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    CGRect rect = [textField bounds];
    rect = [textField convertRect:rect toView:self.scrollView];
    rect.origin.x = 0 ;
    rect.origin.y -= 60 ;
    rect.size.height = 400;

    [self.scrollView scrollRectToVisible:rect animated:YES];
}

回答5:

You can use this function for autoScroll of UITextField

on UITextFieldDelegate

- (void)textFieldDidBeginEditing:(UITextField *)textField {

[self autoScrolTextField:textField onScrollView:self.scrollView];
}




- (void) autoScrolTextField: (UITextField *) textField onScrollView: (UIScrollView *) scrollView { 
 float slidePoint = 0.0f;
float keyBoard_Y_Origin = self.view.bounds.size.height - 216.0f;
float textFieldButtomPoint = textField.superview.frame.origin.y + (textField.frame.origin.y + textField.frame.size.height);

if (keyBoard_Y_Origin < textFieldButtomPoint - scrollView.contentOffset.y) {
    slidePoint = textFieldButtomPoint - keyBoard_Y_Origin + 10.0f;
    CGPoint point = CGPointMake(0.0f, slidePoint);
    scrollView.contentOffset = point;
}

EDIT:

Im now using IQKeyboardManager Kudos to the developer of this, you need to try this.

回答6:

Here is the Swift 4 update to @Supertecnoboff's answer. It worked great for me.

func textFieldDidBeginEditing(_ textField: UITextField) {
    scroll.setContentOffset(CGPoint(x: 0, y: (textField.superview?.frame.origin.y)!), animated: true)
}

func textFieldDidEndEditing(_ textField: UITextField) {
    scroll.setContentOffset(CGPoint(x: 0, y: 0), animated: true)
}

Make sure to extend UITextFieldDelegate and set the textfields' delegate to self.

回答7:

If you have multiple textfields say Textfield1, Textfield2, Textfield3 and you want to scroll the scrollview along the y-axis when textfield2 becomes first responder:

if([Textfield2 isFirstResponder])
{
    scrollView.contentOffset = CGPointMake(0,yourY);
} 

回答8:

As Michael McGuire mentioned in his point #2 above, the system's default behavior misbehaves when the scroll view contains another scroll view between the text field and the scroll view. I've found that the misbehavior also occurs when there's a scroll view merely next to the text field (both embedded in the scroll view that needs to be adjusted to bring the text field into view when the text field wants to start editing. This is on iOS 12.1.

But my solution is different from the above. In my top-level scroll view, which is sub-classed so I can add properties and override methods, I override scrollRectToVisible:animated:. It simply calls its [super scrollRectToVisible:animated:] unless there's a property set that tells it to adjust the rect passed in, which is the frame of the text field. When the property is non-nil, it is a reference to the UITextField in question, and the rect is adjusted so that the scroll view goes further than the system thought it would. So I put this in the UIScrollView's sub-classed header file:

@property (nullable) UITextField *textFieldToBringIntoView;

(with appropriate @synthesize textFieldToBringIntoView; in the implementation. Then I added this override method to the implementation:

- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)how
{
    if (textFieldToBringIntoView) {
       // Do whatever mucking with `rect`'s origin needed to make it visible
       // based on context or its spatial relationship with the other
       // view that the system is getting confused by.

       textFieldToBringIntoView = nil;        // Go back to normal
       }
    [super scrollRectToVisible:rect animated:how];
}

In the delegate method for the UITextField for when it's about to begin editing, just set textFieldToBringIntoView to the textField in question:

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
    // Ensure it scrolls into view so that keyboard doesn't obscure it
    // The system is about to call |scrollRectIntoView:| for the scrolling
    // superview, but the system doesn't get things right in certain cases.

    UIScrollView *parent = (UIScrollView *)textField.superview;
    // (or figure out the parent UIScrollView some other way)

    // Tell the override to do something special just once
    // based on this text field's position in its parent's scroll view.
    parent.textFieldToBringIntoView = textField;
    // The override function will set this back to nil

    return(YES);
}

It seems to work. And if Apple fixes their bug, it seems like it might still work (fingers crossed).