iPhone: Limiting text input in an UITextView

Question

I am trying to limit the amount of LINES a user can have in an UITextView. Let's consider I only want to allow 4 lines (i.e. in the following example, you can't go higher than a height of 84 pixels with the given font in a given UITextView with a width of 200).

I coded this to achieve the limiting and it works fine:

    - (BOOL)textView:(UITextView *)aTextView shouldChangeTextInRange:(NSRange)aRange replacementText:(NSString *)aText {

    NSString* newText = [aTextView.text stringByReplacingCharactersInRange:aRange withString:aText];


    CGSize strSize = [newText sizeWithFont:textView.font constrainedToSize:CGSizeMake(200, 10000) lineBreakMode:UILineBreakModeWordWrap];

if (strSize.height > 100)

    {

        return NO; // can't enter more text
    }
    else
        return YES; // let the textView know that it should handle the inserted text
    }

So far so good. The problem starts when I try to be sneaky and enter as many 'x's as I can before each return. In that case, I can get an extra of 4 lines... which I obviously do not want to allow. I assume that this has something to do with the lineBreakMode? Is there any case to alter this? I haven't found much in the docs (but then again, I usually have a hard time understanding them).

I attached a couple of screenshots to illustrate the problem. I'd be grateful for any suggestions. Thanks a lot!

Normal behaviour - stops after 4 lines Deviant behaviour - too many lines through additional x-es

score 2 · Accepted Answer · answered Apr 09 '11 at 14:45

2

(I hope I understood your problem correctly... )

If you look closely, there's a margin in UITextView. If you use sizeWithFont: carelessly, it can return unexpected results in special cases (because you disrespect the text view's margin).

You should either 1) adjust the width you use in sizeWithFont: to respect the text view's margin or 2) use an auxiliary UITextView object to accurately compute the content size.

answered Apr 09 '11 at 14:45

ryyst

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Thanks a lot for your thoughts. Do you know how I find out what the exact margin is? Is it just something to experiment with? – n.evermind Apr 09 '11 at 18:22
ryyst: This actually WORKS! thanks so much, you were right. It's all down to reducing the 200 a bit. Still, I'm wondering if there is a way to find out the margins programatically and not by guessing. – n.evermind Apr 09 '11 at 18:29
1

@n.evermind: I don't know whether you can find out the margins programmatically - I don't think it is possible using public APIs. By the way, option 2 is described on Apple's dev forums [here](http://discussions.apple.com/thread.jspa?threadID=1923059). (Oh, and make sure you accept this answer if it solved your problem :p) – ryyst Apr 09 '11 at 18:44
sure! i didn't mark it first as I needed to wait for 15 minutes or so, but here we go. Thanks a lot again, this really helped! – n.evermind Apr 10 '11 at 10:23

score 1 · Answer 2 · edited May 23 '17 at 11:48

1

Looks to me like word wrapping is on in UITextView and there's not much you can do to change it (please tell me I am wrong). If you want 4 lines only, maybe 4 UITextField's in a UIScrollView (sent the return key to Next). Or reduce the ContentSize when the length of the render rectangle of each line exceeds the height of one line.

iPhone: Limiting text input in an UITextView

2 Answers2

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