FittableFontLabel

UILabel can shrink font size as follows:

label.minimumScaleFactor = 0.3
label.adjustsFontSizeToFitWidth = true
label.numberOfLines = 1

But it won't always work as expected:

Doesn't fit the label height
Big top / bottom margins when the maxFontSize is huge
Not really customisable
...

That's why FittableFontLabel exists:

Make the text fit the label size: width and height if multilines, width only if single lines
Works with one or several lines
Supports attributed string (custom line spacing...)
Customize maxFontSize without using default label font size
Auto-layout compliant
UILabel extension if we want to use UILabel
Customisable from xibs / storyboards when using the UILabel's subclass FittableFontLabel
...

Multilines UILabel:

Multilines UILabel with attributed string (lines spacing):

Single line UILabel:

Usage

let aFittableFontLabel = FittableFontLabel(frame: CGRect(x: 0, y: 0, width: 300, height: 100))
aFittableFontLabel.autoFittableFont = true
aFittableFontLabel.lineBreakMode = .ByWordWrapping
aFittableFontLabel.numberOfLines = 0 // or 1...
aFittableFontLabel.text = "?"
// Change the text, it will always fit the label frame!

Check the sample project for advanced usage.

Note: The label lineBreakMode must be set to NSLineBreakByWordWrapping in order to work.

Installation

iOS 8.0+

CocoaPods

Add pod FittableFontLabel to your Podfile.

Carthage

Add github "tbaranes/FittableFontLabel" to your Cartfile.

Swift Package Manager

FittableFontLabel is available on SPM. Just add the following to your Package file:

import PackageDescription

let package = Package(
    dependencies: [
        .Package(url: "https://github.com/tbaranes/FittableFontLabel.git", majorVersion: 1)
    ]
)

Manual Installation

Just drag the Source/*.swift files into your project.

UILabel extension

func fontSizeToFit(maxFontSize: CGFloat = 100, 
					  minFontScale: CGFloat = 0.1,
					  rectSize: CGSize? = nil)

Adjust the font size to make the current text fit the label frame.

maxFontSize: the biggest font size to use during drawing. The default value is 100
minFontScale: the scale factor that determines the smallest font size to use during drawing. The default value is 0.1
rectSize: the size where the text must fit. The default value is the label bounds

func fontSizeThatFits(
        text string: String, 
        maxFontSize: CGFloat = 100, 
        minFontScale: CGFloat = 0.1,
        rectSize: CGSize? = nil) -> CGFloat

Returns the font size that can make the text parameter fit the label frame.

text: the text that needs to fit in the label
maxFontSize: the biggest font size that can be returned. The default value is 100
minFontScale: the scale factor that determines the smallest font size that can be returned. The default value is 0.1
rectSize: the size where the text must fit. The default value is the label bounds