Question

Starts like this, which I like:

But then I add a segment and this happens:

The width is set in IB, not in code.

All I need is a method to calculate width on the fly. At the end, it would do something like this:

control.width = (labelWidths + marginWidths);
// where marginWidths = (marginWidth * control.numberOfSegments)

Answer 1

The method in prgrmr’s answer here works fine for its intended purpose, but this is not it.

Rather than adding unnecessary overhead with custom UILabel subviews,
I’ve modified the example code in the above link to come up with this:

- (void)resizeSegmentsToFitTitles:(UISegmentedControl *)control {
    CGFloat textWidth = 0; // total width of all text labels
    CGFloat marginWidth = 0; // total width of all margins
    NSUInteger nSegments = control.subviews.count;
    UIView *aSegment = [control.subviews objectAtIndex:0];
    UIFont *theFont = nil;

    // get font for segment title label
    for (UILabel *label in aSegment.subviews) {
        if ([label isKindOfClass:[UILabel class]]) {
            theFont = label.font;
            break;
        }
    }

    // calculate width of text in each segment
    for (NSUInteger i = 0; i < nSegments; i++) {
        NSString *title = [control titleForSegmentAtIndex:i];
        CGFloat width = [title sizeWithFont:theFont].width;
        CGFloat margin = 15;

        if (width > 200) {
            NSString *ellipsis = @"…";
            CGFloat width2 = [ellipsis sizeWithFont:theFont].width;

            while (width > 200-width2) {
                title = [title substringToIndex:title.length-1];
                width = [title sizeWithFont:theFont].width;
            }

            title = [title stringByAppendingString:ellipsis];
        }

        [control setTitle:title forSegmentAtIndex:i];

        textWidth += width;
        marginWidth += margin;
    }

    // resize segments to accomodate text size, evenly split total margin width
    for (NSUInteger i = 0; i < nSegments; i++) {
        // size for label width plus an equal share of the space
        CGFloat textWidth = [[control titleForSegmentAtIndex:i]
                             sizeWithFont:theFont].width;
        // the control leaves a 1 pixel gap between segments if width
        // is not an integer value; roundf() fixes this
        CGFloat segWidth = roundf(textWidth + (marginWidth / nSegments));
        [control setWidth:segWidth forSegmentAtIndex:i];
    }

    // set control width
    [control setFrame:CGRectMake(0, 0, (textWidth + marginWidth), 30)];
}