How to fit text in a circle in UILabel

Question

I\'d like to flow the text in UILabel into a circle (instead of rect). I did some experiments with NSLayoutManager, NSTextContainer an

Answer 1

Here is my contribution to the above question in Swift 3. https://github.com/icatmed/ICRoundLabel.git

import UIKit
import CoreText

@IBDesignable
open class ICRoundLabel: UILabel {

// Switch on/off text rounding, is on by default
@IBInspectable open dynamic var isRounded:Bool = true {
    didSet{
        setNeedsDisplay()
    }
}

// Specify text alignment
@available(*, unavailable, message: "This property is reserved for Interface Builder. Use 'roundedTextAlignment' instead.")
@IBInspectable open dynamic var alignment:UInt8 {
    set{
        self.roundedTextAlignment = CTTextAlignment(rawValue: newValue)!
        setNeedsDisplay()
    }
    get{
        return roundedTextAlignment.rawValue
    }
}

// Font scale
@IBInspectable open dynamic var fillTextInCenter:Bool = true {
    didSet{
        setNeedsDisplay()
    }
}

// Font step
@available(*, unavailable, message: "This property is reserved for Interface Builder. Use 'internalFontStep' instead.")
@IBInspectable open dynamic var fontStep:CGFloat {
    set(newValue) {
        internalFontStep = max(newValue, 0.1)
    }
    get {
        return internalFontStep
    }
}

open var roundedTextAlignment:CTTextAlignment = .center
open var internalFontStep:CGFloat = 1

override open func drawText(in rect: CGRect) {

    // Check if custom text draw is needed
    if !isRounded {
        super.drawText(in: rect)
        return
    }

    // Check if text exists
    guard let text = self.text else {
        return
    }

    if text == "" {
        return
    }

    // Get graphics context
    guard let context = UIGraphicsGetCurrentContext() else {
        return
    }

    //MARK: Create attributed string
    var stringRange = NSMakeRange(0, text.characters.count)
    let attrString = CFAttributedStringCreate(kCFAllocatorDefault, text as CFString!, attributedText?.attributes(at: 0, effectiveRange: &stringRange) as CFDictionary!)
    let attributedString = CFAttributedStringCreateMutableCopy(kCFAllocatorDefault, CFIndex.max, attrString)!
    let stringLength = CFAttributedStringGetLength(attributedString)

    // Set a paragraph style
    let cfStringRange = CFRangeMake(0, stringLength)
    let settings = [CTParagraphStyleSetting(spec: .alignment, valueSize: MemoryLayout.size(ofValue: roundedTextAlignment), value: &roundedTextAlignment)]
    let paragraphStyle = CTParagraphStyleCreate(settings, 1)

    CFAttributedStringSetAttribute(attributedString, cfStringRange, kCTParagraphStyleAttributeName, paragraphStyle)

    // Make custom transitions with context
    context.translateBy(x: 0.0, y: frame.size.height)
    context.scaleBy(x: 1.0, y: -1.0)

    // New drawing rect with insets
    let drawingRect = CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: rect.size.width, height: rect.size.height))

    // Align text in center
    var boundingBox = text.boundingRect(with: drawingRect.size, options: NSStringDrawingOptions.usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)

    //MARK: Create elliptical path
    var path = CGPath(roundedRect: drawingRect, cornerWidth: drawingRect.width/2, cornerHeight: drawingRect.height/2, transform: nil)

    //MARK: Frame and range calculation nested function
    func getTextFrameRange() -> (CTFrame, CFRange) {
        let textFrame = CTFramesetterCreateFrame(CTFramesetterCreateWithAttributedString(attributedString), cfStringRange, path, nil)
        let rangeThatFits = CTFrameGetVisibleStringRange(textFrame)
        return (textFrame, rangeThatFits)
    }

    var textFrame:CTFrame
    var rangeThatFits:CFRange

    //MARK: Scaling font size if needed

    if fillTextInCenter {

        var fontSize = font.pointSize
        var estimatedFont = font.withSize(fontSize)

        // Pin text in center of initial rect
        var boxHeight = ceil(boundingBox.height)

        func updateBoundingBox() {
            boundingBox.origin = CGPoint(x: ceil((drawingRect.size.height - boxHeight)/2), y: ceil((drawingRect.size.height - boxHeight)/2))
            boundingBox.size = CGSize(width: boxHeight, height: boxHeight)
        }

        path = CGPath(roundedRect: boundingBox, cornerWidth: boundingBox.width/2, cornerHeight: boundingBox.height/2, transform: nil)

        (_, rangeThatFits) = getTextFrameRange()

        updateBoundingBox()

        // Fit text in center
        while cfStringRange.length != rangeThatFits.length {

            // Increase size of bounding box size if needed
            // or decrease font size
            if boundingBox.width < drawingRect.width {

                boxHeight += 1

                //Update bounding box accoringly to new box size
                updateBoundingBox()

                path = CGPath(roundedRect: boundingBox, cornerWidth: boundingBox.width/2, cornerHeight: boundingBox.height/2, transform: nil)

                (_, rangeThatFits) = getTextFrameRange()

                continue
            } else {

                CFAttributedStringSetAttribute(attributedString, cfStringRange, kCTFontAttributeName, estimatedFont)

                (_, rangeThatFits) = getTextFrameRange()

                // Increase or decrease font size
                fontSize += cfStringRange.length < rangeThatFits.length ? internalFontStep : -internalFontStep
                estimatedFont = font.withSize(fontSize)
            }
        }
    }

    //MARK: Draw the text frame in the view's graphics context
    (textFrame, _) = getTextFrameRange()
    CTFrameDraw(textFrame, context)

}

@IBInspectable var borderColor: UIColor = UIColor.white {
    didSet {
        layer.borderColor = borderColor.cgColor
    }
}

@IBInspectable var borderWidth: CGFloat = 1.0 {
    didSet {
        layer.borderWidth = borderWidth
    }
}

override open func layoutSubviews() {
    super.layoutSubviews()
    layer.cornerRadius = 0.5 * bounds.size.width
    clipsToBounds = true


}

}