How can I compute the number of lines of a UILabel

Question

This question already has answers here:

How to find UILabel's number of Lines (7 answers)

Closed 6 years ago.

How can I compute the number of lines of a UILabel with a fixed width and a given text ?

Answer 1

You can compute the vertical height necessary to display the string using the sizeWithFont:constrainedToSize: method on NSString. Given that size, you can resize the label to display the entire string.

Answer 2

First get the height of the label from the label size using constrainedSize

CGSize labelSize = [label.text sizeWithFont:label.font 
                            constrainedToSize:label.frame.size 
                                lineBreakMode:UILineBreakModeWordWrap];
CGFloat labelHeight = labelSize.height;

once you have the label height then check the number of lines with the font size where fontsize is the size you are using for your label. e.g it could be 10 or depending on your requirements

CGSize sizeOfText = [label.text sizeWithFont:label.font 
                        constrainedToSize:label.frame.size 
                            lineBreakMode:UILineBreakModeWordWrap];
int numberOfLines = sizeOfText.height / label.font.pointSize;

Answer 3

This code assumes label has the desired text and its frame is already set to the desired width.

- (int)lineCountForLabel:(UILabel *)label {
    CGSize constrain = CGSizeMake(label.bounds.size.width, FLT_MAX);
    CGSize size = [label.text sizeWithFont:label.font constrainedToSize:constrain lineBreakMode:UILineBreakModeWordWrap];

    return ceil(size.height / label.font.lineHeight);
}

Update:

If all you want is to determine the required height for the label based on its text and current width, then change this to:

- (CGSize)sizeForLabel:(UILabel *)label {
    CGSize constrain = CGSizeMake(label.bounds.size.width, FLT_MAX);
    CGSize size = [label.text sizeWithFont:label.font constrainedToSize:constrain lineBreakMode:UILineBreakModeWordWrap];

    return size;
}

The returned size is the proper width and height to contain the label.