Dynamically changing font size of UILabel

Single line:

factLabel.numberOfLines = 1;factLabel.minimumFontSize = 8;factLabel.adjustsFontSizeToFitWidth = YES;

The above code will adjust your text's font size down to (for example) 8 trying to fit your text within the label. numberOfLines = 1 is mandatory.

Multiple lines:

For numberOfLines > 1 there is a method to figure out the size of final text through NSString's sizeWithFont:... UIKit addition methods, for example:

CGSize lLabelSize = [yourText sizeWithFont:factLabel.font                                  forWidth:factLabel.frame.size.width                             lineBreakMode:factLabel.lineBreakMode];

After that you can just resize your label using resulting lLabelSize, for example (assuming that you will change only label's height):

factLabel.frame = CGRectMake(factLabel.frame.origin.x, factLabel.frame.origin.y, factLabel.frame.size.width, lLabelSize.height);

iOS6

Single line:

Starting with iOS6, minimumFontSize has been deprecated. The line

factLabel.minimumFontSize = 8.;

can be changed to:

factLabel.minimumScaleFactor = 8./factLabel.font.pointSize;

iOS7

Multiple lines:

Starting with iOS7, sizeWithFont becomes deprecated. Multiline case is reduced to:

factLabel.numberOfLines = 0;factLabel.lineBreakMode = NSLineBreakByWordWrapping;CGSize maximumLabelSize = CGSizeMake(factLabel.frame.size.width, CGFLOAT_MAX);CGSize expectSize = [factLabel sizeThatFits:maximumLabelSize];factLabel.frame = CGRectMake(factLabel.frame.origin.x, factLabel.frame.origin.y, expectSize.width, expectSize.height);

iOS 13 (Swift 5):

label.adjustsFontSizeToFitWidth = truelabel.minimumScaleFactor = 0.5

minimumFontSize has been deprecated with iOS 6. You can use minimumScaleFactor.

yourLabel.adjustsFontSizeToFitWidth=YES;yourLabel.minimumScaleFactor=0.5;

This will take care of your font size according width of label and text.

Single line- There are two ways, you can simply change.

1- Pragmatically (Swift 3)

Just add the following code

    yourLabel.numberOfLines = 1;    yourLabel.minimumScaleFactor = 0.7;    yourLabel.adjustsFontSizeToFitWidth = true;

2 - Using UILabel Attributes inspector

i- Select your label- Set number of lines 1.ii- Autoshrink-  Select Minimum Font Scale from drop downiii- Set Minimum Font Scale value as you wish , I have set 0.7 as in below image. (default is 0.5)