How to truncate UITextView contents to fit a reduced size?

I'm having real trouble getting my head around this issue.

As the title suggests, I have several UITextViews on a view in an iPhone application. I am programmatically creating them and successfully filling that textview with text, but in some cases the text I put in the view takes up more space than the frame I allocate for it. In this case I would like the text to be truncated, but I can't figure out how to do it.

I have predefined the following constants;

#define viewOriginX  20
#define viewOriginY 180

Here is my UITextView creation code;

textViewOne = [[UITextView alloc] initWithFrame:CGRectMake(viewOriginX, viewOriginY + 65, 280, 45];
textViewOne.delegate = self;
textViewOne.scrollEnabled = NO;
textViewOne.contentInset = UIEdgeInsetsZero;
textViewOne.font = viewFont;
textViewOne.textColor = [UIColor blackColor];
textViewOne.textAlignment = UITextAlignmentLeft;
[self.view addSubview:textViewOne];

In some cases I have 15 to 20 lines of text in here and I would like to truncate it to 2 lines.

Can anyone help me in the right direction?

Thanks in advance! :D

Answers


You can do a character count. For example, if you have UITextField like this:

+--------------------+
|This is a string in |
|a text view.        |
+--------------------+

you have something like 20 characters per line. If you know that number you can simply truncate your string by -substringToIndex: method.

int maxCharacters = 40; // change it to your max
if([myString length] > maxCharacters) {
    myString = [myString substringToIndex:maxCharacters];
}

You can also think about UILabel. Since you need only 2 lines of text, UILabel's numberOfLines property can solve your problem.


Original Answer (iOS 6 and below)

Sadly, UILabel with numberOfLines wont do it if you need the view to be editable. Or you want UITextView's (native) vertical alignment.

Here's an NSString category that deletes words from a string, according to it's size in a rect:

@interface NSString (StringThatFits)
- (NSString *)stringByDeletingWordsFromStringToFit:(CGRect)rect
                                         withInset:(CGFloat)inset
                                         usingFont:(UIFont *)font
@end

@implementation NSString (StringThatFits)
- (NSString *)stringByDeletingWordsFromStringToFit:(CGRect)rect
                                         withInset:(CGFloat)inset
                                         usingFont:(UIFont *)font
{
    NSString *result = [self copy];
    CGSize maxSize = CGSizeMake(rect.size.width  - (inset * 2), FLT_MAX);
    CGSize size = [result sizeWithFont:font
                           constrainedToSize:maxSize
                               lineBreakMode:UILineBreakModeWordWrap];
    NSRange range;

    if (rect.size.height < size.height)
        while (rect.size.height < size.height) {

            range = [result rangeOfString:@" "
                                        options:NSBackwardsSearch];

            if (range.location != NSNotFound && range.location > 0 ) {
                result = [result substringToIndex:range.location];
            } else {
                result = [result substringToIndex:result.length - 1];
            }

            size = [result sizeWithFont:font
                            constrainedToSize:maxSize
                                lineBreakMode:UILineBreakModeWordWrap];
        }

    return result;
}
@end

For a UITextView, use an inset of 8 to account for the way UIKit draws them:

CGRect rect = aTextView.frame;
NSString *truncatedString = [theString stringByDeletingWordsFromStringToFit:rect
                                     withInset:8.f
                                     usingFont:theTextView.font];
Updated Answer (iOS 7)

Now UITextView uses TextKit internally, it's much easier.

Rather than truncating the actual string, set the text (or attributedText) property to the whole string and truncate the amount of text displayed in the container (just like we do with UILabel):

self.textView.scrollEnabled = NO;
self.textView.textContainer.maximumNumberOfLines = 0;
self.textView.textContainer.lineBreakMode = NSLineBreakByTruncatingTail;

Because sizeWithFont:constrainedToSize:lineBreakMode: is deprecated in iOS 7, I made a few changes:

- (NSString *)stringByDeletingWordsFromStringToFit:(CGRect)rect
                                     withInset:(CGFloat)inset
                                     usingFont:(UIFont *)font
{
    NSString *result = [self copy];
    CGSize maxSize = CGSizeMake(rect.size.width  - (inset * 2), FLT_MAX);
    if (!font) font = [UIFont systemFontOfSize:[UIFont systemFontSize]];
    CGRect boundingRect = [result boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName: font, } context:nil];
    CGSize size = boundingRect.size;
    NSRange range;

    if (rect.size.height < size.height)
        while (rect.size.height < size.height) {

            range = [result rangeOfString:@" "
                                    options:NSBackwardsSearch];

            if (range.location != NSNotFound && range.location > 0 ) {
                result = [result substringToIndex:range.location];
            } else {
                result = [result substringToIndex:result.length - 1];
            }

            if (!font) font = [UIFont systemFontOfSize:[UIFont systemFontSize]];
            CGRect boundingRect = [result boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName: font, } context:nil];
            size = boundingRect.size;
        }

    return result;

}


Here's a peace of code i wrote to truncate a string (by words) to fit a certain width and height:

- (NSString *)stringByTruncatingString:(NSString *)string toHeight:(CGFloat)height maxWidth:(CGFloat)width withFont: (UIFont *)font {

    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
    NSDictionary *attrDict = [NSDictionary dictionaryWithObjectsAndKeys:font, NSFontAttributeName, paragraphStyle, NSParagraphStyleAttributeName, nil];
    NSMutableString *truncatedString = [string mutableCopy];

    if ([string sizeWithAttributes: @{NSFontAttributeName: font}].height > height) {
        // this line is optional, i wrote for better performance in case the string is too big
        if([truncatedString length] > 150) truncatedString = [[truncatedString substringToIndex:150] mutableCopy];
        // keep removing the last word until string is short enough
        while ([truncatedString boundingRectWithSize:CGSizeMake(width, CGFLOAT_MAX) options:NSStringDrawingTruncatesLastVisibleLine|NSStringDrawingUsesLineFragmentOrigin attributes:attrDict context:nil].size.height > height) {
            NSRange wordrange= [truncatedString rangeOfString: @" " options: NSBackwardsSearch];
            truncatedString = [[truncatedString substringToIndex: wordrange.location] mutableCopy];
        }
        // add elipsis to the end
        truncatedString = [NSMutableString stringWithFormat:@"%@...",truncatedString];
    }
    return truncatedString;
}

Usage:

NSString *smallString = [self stringByTruncatingString:veryBigString toHeight:65 maxWidth:200 withFont:[UIFont systemFontSize:14.0f]];

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