UITextView setText should not jump to top in ios8

问题:

Following iOS 8 code is called every second:

- (void)appendString(NSString *)newString toTextView:(UITextView *)textView {
    textView.scrollEnabled = NO;
    textView.text = [NSString stringWithFormat:@"%@%@%@", textView.text, newString, @"\n"];
    textView.scrollEnabled = YES;
    [textView scrollRangeToVisible:NSMakeRange(textView.text.length, 0)];
}

The goal is to have the same scrolling down behaviour as the XCode console when the text starts running off the bottom. Unfortunately, setText causes the view to reset to the top before I can scroll down again with scrollRangeToVisible.

This was solved in iOS7 with the above code and it worked, but after upgrading last week to iOS8, that solution no longer seems to work anymore.

I can't figure out how to get this going fluently without the jumping behaviour?

回答1:

Try just to add text to UITextView (without scrollRangeToVisible/scrollEnabled). It seams that hack with scroll enabled/disabled is no more needed in iOS8 SDK. UITextView scrolls automatically.

回答2:

I meet this problem too. You can try this.

textView.layoutManager.allowsNonContiguousLayout = NO;

refrence:http://hayatomo.com/2014/09/26/1307

回答3:

The following two solutions don't work for me on iOS 8.0.

textView.scrollEnabled = NO;
[textView.setText: text];
textView.scrollEnabled = YES;

and

CGPoint offset = textView.contentOffset;
[textView.setText: text];
[textView setContentOffset:offset];

I setup a delegate to the textview to monitor the scroll event, and noticed that after my operation to restore the offset, the offset is reset to 0 again. So I instead use the main operation queue to make sure my restore operation happens after the "reset to 0" option.

Here's my solution that works for iOS 8.0.

CGPoint offset = self.textView.contentOffset;
self.textView.attributedText = replace;
[[NSOperationQueue mainQueue] addOperationWithBlock: ^{
    [self.textView setContentOffset: offset];
}];