sizeWithFont doesn't give correct height for UITextView if there is a long string in the text being wrapped

问题

Is there a way to get the correct size of an NSString using:

- (CGSize)sizeWithFont:(UIFont *)font forWidth:(CGFloat)width lineBreakMode:(UILineBreakMode)lineBreakMode

that doesnt get thrown off by 2 or 3 hundred character strings. At the moment if I try to use this method on these long strings it incorrectly calculates them and I end up with lots of whitespace at the bottom of the UITextView.

I've tried using UILineBreakModeWordWrap and UILineBreakModeCharacterWrap.

the resizing is being done in

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    CGFloat     result = 44.0f;
    NSString*   text = nil;
    CGFloat     width = 0;
    CGFloat     tableViewWidth;
    CGRect      bounds = [UIScreen mainScreen].bounds;

    tableViewWidth = bounds.size.width;


    width = tableViewWidth - 150;       

    text = stringWithLongWords;

    if (text) {
        CGSize      textSize = { width, 20000.0f };     
        CGSize      size = [text sizeWithFont:[UIFont systemFontOfSize:10.0f] constrainedToSize:textSize lineBreakMode:UILineBreakModeWordWrap];

        size.height += 50.0f;               
        result = MAX(size.height, 44.0f+30.0f); 
    }

    return result;
}

回答1:

UITextView is not exactly like a UILabel wrapped in a UIScrollView. It has line spacing different from the font size and margins that sizeWithFont:constrainedToSize:linkBreakMode: doesn't account for.

Knowing your font size you might be able to calculate the # of lines and take line spacing into account. You can guess at the margins and try to trick sizeWithFont: to give a more useful answer.

The popular solutions seem to be:

just use a UILabel if you don't need any UITextView functionality
if you need hyperlinks, overlay UIButtons that look like hyperlinks over a UILabel
use an off-screen UITextView and its sizeToFit method to get a real answer

I had no luck w/ the 3rd option but it sounds like it should work, so perhaps I did something wrong.

I'm going to try using a UILabel and overlaying buttons for hyperlinks. We'll see how that turns out.

If that fails, there is always the option taken by Loren Brichter (of Tweetie fame): draw everything into a UIView yourself using CoreGraphics.

Good luck!

回答2:

Check out this post How do I size a UITextView to its content?

It looks like textView.contentSize.height should work (with the caveat that the the correct contentSize is only available after the UITextView has been added to the view with addSubview)

回答3:

You said that you have a UITableView with differing heights. Have you set the reuse identifier to the same thing for all of the cells? It could be that older cells with their height already set are being reused. If this is the problem, you should resize the cell again when it's being reused.

回答4:

The best solution I have found so far is to have a separate hidden UITextView with the same font settings, and set its text. After that its contetSize should be accurate.

回答5:

The width you are using is the width for your UITextView... but you aren't concerned with that width, you are concerned with the width of the actual text area nested inside the text view.

UITextViews, by default, have padding around their borders to produce a space in-between the typed text and the edge of the UITextView a few pixels wide (and long for the top)... To get the correct size you shouldn't use

textView.frame.size.width

but rather,

textView.frame.size.width-(textView.contentInset.left+textView.contentInset.right+textView.textContainerInset.left+textView.textContainerInset.right+textView.textContainer.lineFragmentPadding/*left*/+textView.textContainer.lineFragmentPadding/*right*/)

^Which takes the width of the UITextView and subtracts out all the padding so you are left with the width of just the type-able text area.

Same goes for height except for lineFragmentPadding doesn't have a bottom so you only subtract it out once instead of twice.

The final code is something like this:

    CGSize textViewContentSize = CGSizeMake(theTextView.frame.size.width-(theTextView.contentInset.left+theTextView.contentInset.right+theTextView.textContainerInset.left+theTextView.textContainerInset.right+theTextView.textContainer.lineFragmentPadding/*left*/+theTextView.textContainer.lineFragmentPadding/*right*/), theTextView.frame.size.height-(theTextView.contentInset.top+theTextView.contentInset.bottom+theTextView.textContainerInset.top+theTextView.textContainerInset.bottom+theTextView.textContainer.lineFragmentPadding/*top*//*+theTextView.textContainer.lineFragmentPadding*//*there is no bottom padding*/));

    CGSize calculatedSize = [theTextView.text sizeWithFont:theTextView.font
                                          constrainedToSize:textViewContentSize
                                              lineBreakMode:NSLineBreakByWordWrapping];


    CGSize adjustedSize = CGSizeMake(ceilf(calculatedSize.width), ceilf(calculatedSize.height));

回答6:

Inspired by @MrNickBarker's answer, here's my solution:

CGFloat width = 280.0f;

UITextView *t = [[UITextView alloc] init];
[t setFont:[UIFont systemFontOfSize:17]];
[label setText:@"some short or long text, works both"];

CGRect frame = CGRectMake(0, 0, width, 0);
[t setFrame:frame];
// Here's the trick: after applying the 0-frame, the content size is calculated and can be used in a second invocation
frame = CGRectMake(0, 0, width, t.contentSize.height);
[t setFrame:frame];

The only issue remaining for me is that this doesn't work with modified insets.

Still can't believe such twists are required, but since -[NSString sizeWithFont:forWidth:lineBreakMode:] does not respect insets, paddings, margins, line spacings and the like, it seems this is the only working solution at the moment (i.e. iOS 6).

来源：https://stackoverflow.com/questions/2330939/sizewithfont-doesnt-give-correct-height-for-uitextview-if-there-is-a-long-strin

标签

iphone

objective-c

nsstring

uitextfield