Strange behavior when trying to align vertically UILabel text

Question

I'm developing an iPhone app with latest SDK and XCode 4.2

I'm using this code to align vertically a text set it previously in an UILabel. Here is the code:

- (void)resizeLabel:(UILabel *)label
{
    CGSize maximumLabelSize = label.frame.size;

    CGSize expectedLabelSize = [label.text sizeWithFont:label.font 
                                      constrainedToSize:maximumLabelSize 
                                          lineBreakMode:label.lineBreakMode]; 

    //adjust the label the the new height.
    CGRect newFrame = label.frame;
    NSLog(@"NumLines: %d, OldWidth: %f, NewWidth: %f, OldHeight: %f, newHeight: %f", label.numberOfLines, maximumLabelSize.width,  expectedLabelSize.width, maximumLabelSize.height, expectedLabelSize.height);
    newFrame.size.height = expectedLabelSize.height;
    label.frame = newFrame;
}

For text: "Iglesia de la Merced" I get:

NumLines: 2, OldWidth: 205.000000, NewWidth: 153.000000, OldHeight: 39.000000, newHeight: 21.000000

For text: "Antiguo convento de los merdarios" I get

NumLines: 2, OldWidth: 205.000000, NewWidth: 187.000000, OldHeight: 39.000000, newHeight: 42.000000

Both are set up to use two lines but text is always drawn in one line only.

Why am I getting double height when expectedLabelSize.width is smaller than maximumLabelSize.width?

vikingosegundo · Accepted Answer · 2012-02-04T19:23:30.530

1

It is wrapping in two lines, I guess.

from the doc:

This method computes the metrics needed to draw the specified string. This method lays out the receiver’s text and attempts to make it fit the specified size using the specified font and line break options. During layout, the method may break the text onto multiple lines to make it fit better. If the receiver’s text does not completely fit in the specified size, it lays out as much of the text as possible and truncates it (for layout purposes only) according to the specified line break mode. It then returns the size of the resulting truncated string. If the height specified in the size parameter is less than a single line of text, this method may return a height value that is bigger than the one specified.

Something to mention:
if you set numberOfLines to 0, it will automatically use as many lines as possible and needed.

Also try:

myUILabel.numberOfLines = 0;
myUILabel.text = @"Antiguo convento de los merdarios";
[myUILabel sizeToFit];

edited Feb 04 '12 at 19:23

answered Feb 04 '12 at 17:49

vikingosegundo

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Yes, I set up for two lines in Interface Builder. – VansFannel Feb 04 '12 at 18:02
`sizeWithFont:constrainedToSize:lineBreakMode:` does not care about what you do in nib-files. it just calculates, what is needed. and the second text needs 2 lines for the contained size (aka maximum size). – vikingosegundo Feb 04 '12 at 18:05
I have updated my question because as you can see both are set up to use two lines, but second one it is bigger. – VansFannel Feb 04 '12 at 18:09
my hint for numberOfLines is misleading. sorry. as explained above, `sizeWithFont:constrainedToSize:lineBreakMode:`does not take it in account. your numbers are just saying, that for the first string one line would be sufficient, while the second needs two. – vikingosegundo Feb 04 '12 at 18:12
you are getting the minimal bounding box. – vikingosegundo Feb 04 '12 at 18:13
I don't know why it needs two lines if expectedLabelSize.width is smaller than maximumLabelSize.width. – VansFannel Feb 04 '12 at 18:13
it is the width, AFTER it was breaker into 2 lines. and as you have break by words, it breaks before the word, that would be truncated. – vikingosegundo Feb 04 '12 at 18:17
By the way, I've forgotten to say that text is draw in one line only. – VansFannel Feb 04 '12 at 18:33
yeah, I know this happens. the method seems to be inaccurate. – vikingosegundo Feb 04 '12 at 18:34
http://stackoverflow.com/questions/1407106/why-is-sizewithfontconstrainedtosizelinebreakmode-returning-an-incorrect-size – vikingosegundo Feb 04 '12 at 18:39
what information made u accept the answer? I would like to point it out in the answer. thanks. – vikingosegundo Feb 04 '12 at 19:08
This one: stackoverflow.com/a/1304001/106435 – VansFannel Feb 04 '12 at 19:19

Strange behavior when trying to align vertically UILabel text

1 Answers1