Disable UIScrollView scrolling when UITextField be

Question

When a UITextField, embedded in a UIScrollView becomes first responder, by lets say the user typing in some character, the UIScrollView scrolls to that Field automatically, is there any way to disable that?

Duplicate rdar://16538222 over

Answer 1

I have a collection view with a text field at the very top, mimicking the UITableView.tableHeaderView. This text field is located in the negative content offset space so that it doesn't interfere with the rest of the collection view. I basically am detecting whether or not the user is performing the scrolling in the scroll view and whether or not the text field is first responder and if the scroll view is being scrolled beyond the top of the scroll view's content inset. This exact code won't necessarily help anyone but they could manipulate it to fit their case.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

    // This is solving the issue where making the text field first responder
    // automatically scrolls the scrollview down by the height of the search bar.
    if (!scrollView.isDragging && !scrollView.isDecelerating &&
        self.searchField.isFirstResponder &&
        (scrollView.contentOffset.y < -scrollView.contentInset.top)) {

        [scrollView setContentOffset:CGPointMake(scrollView.contentOffset.x, -scrollView.contentInset.top) animated:NO];
    }
}

Answer 2

This is the way I do it:

It is very simple, you get to return your own contentOffset for any scrollRectToVisible.

This way you are not harming the normal behaviour and flow of things - just providing the same functionality in the same channel, with your own improvements.

#import <UIKit/UIKit.h>

@protocol ExtendedScrollViewDelegate <NSObject>

- (CGPoint)scrollView:(UIScrollView*)scrollView offsetForScrollingToVisibleRect:(CGRect)rect;

@end

@interface ExtendedScrollView : UIScrollView

@property (nonatomic, unsafe_unretained) id<ExtendedScrollViewDelegate> scrollToVisibleDelegate;

@end

#import "ExtendedScrollView.h"

@implementation ExtendedScrollView

- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)animated
{
    if (_scrollToVisibleDelegate && [_scrollToVisibleDelegate respondsToSelector:@selector(scrollView:offsetForScrollingToVisibleRect:)])
    {
        [self setContentOffset:[_scrollToVisibleDelegate scrollView:self offsetForScrollingToVisibleRect:rect] animated:animated];
    }
    else
    {
        [super scrollRectToVisible:rect animated:animated];
    }
}

@end

Answer 3

I've been struggling with the same problem, and at last I've found a solution.

I've investigated how the auto-scroll is done by tracking the call-trace, and found that an internal [UIFieldEditor scrollSelectionToVisible] is called when a letter is typed into the UITextField. This method seems to act on the UIScrollView of the nearest ancestor of the UITextField.

So, on textFieldDidBeginEditing, by wrapping the UITextField with a new UIScrollView with the same size of it (that is, inserting the view in between the UITextField and it's superview), this will block the auto-scroll. Finally remove this wrapper on textFieldDidEndEditing.

The code goes like:

- (void)textFieldDidBeginEditing:(UITextField*)textField {  
    UIScrollView *wrap = [[[UIScrollView alloc] initWithFrame:textField.frame] autorelease];  
    [textField.superview addSubview:wrap];  
    [textField setFrame:CGRectMake(0, 0, textField.frame.size.width, textField.frame.size.height)]; 
    [wrap addSubview: textField];  
}  

- (void)textFieldDidEndEditing:(UITextField*)textField {  
  UIScrollView *wrap = (UIScrollView *)textField.superview;  
  [textField setFrame:CGRectMake(wrap.frame.origin.x, wrap.frame.origin.y, wrap.frame.size.width, textField.frame.size.height)];
  [wrap.superview addSubview:textField];  
  [wrap removeFromSuperview];  
}  

hope this helps!

Answer 4

I had the same issue with disabling auto-scrolling of a UITextView being a cell of UITableView. I was able to resolve it using the following approach:

@interface MyTableViewController : UITableViewController<UITextViewDelegate>

@implementation MyTableViewController {
    BOOL preventScrolling;
    // ...
}

// ... set self as the delegate of the text view

- (void)textViewDidBeginEditing:(UITextView *)textView {
    preventScrolling = YES;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    if (preventScrolling) {
        [self.tableView setContentOffset:CGPointMake(0, -self.tableView.contentInset.top) animated:NO];
    }
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    preventScrolling = NO;
}

Defining scrollViewWillBeginDragging is used for restoring the default scrolling behaviour, when the user himself initiates scrolling.

Answer 5

It looks like UIScrollview which contains UITextfield, auto adjusts its content offset; when textfield is going to become first responder. This can be solved by adding textfield in scrollview of same size first, and then adding in to main scroll view. instead of directly adding in to main scrollview

    // Swift

    let rect = CGRect(x: 0, y: 0, width: 200, height: 50)

    let txtfld = UITextField()
    txtfld.frame = CGRect(x: 0, y: 0, width: rect.width, height: rect.height)

    let txtFieldContainerScrollView = UIScrollView()
    txtFieldContainerScrollView.frame = rect
    txtFieldContainerScrollView.addSubview(txtfld)
    // Now add this txtFieldContainerScrollView in desired UITableViewCell, UISCrollView.. etc
    self.mainScrollView.addSubview(txtFieldContainerScrollView)

    // Am33T

Answer 6

Building on Moshe's answer...

Subclass UIScrollView and override the following method:

- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)animated

Leave it empty. Job done!