Как поместить текст в круг в UILabel

вы не можете сделать это в UILabel, потому что это не дает вам доступ к стеку TextKit. Что я делаю, так это создать свой собственный стек TextKit и подкласс NSTextContainer:

-(CGRect)lineFragmentRectForProposedRect:(CGRect)proposedRect atIndex:(NSUInteger)characterIndex writingDirection:(NSWritingDirection)baseWritingDirection remainingRect:(CGRect *)remainingRect {
    CGRect result = [super lineFragmentRectForProposedRect:proposedRect atIndex:characterIndex writingDirection:baseWritingDirection remainingRect:remainingRect];
    CGRect r = CGRectMake(0,0,self.size.width,self.size.height);
    UIBezierPath* circle = [UIBezierPath bezierPathWithOvalInRect:r];
    CGPoint p = result.origin;
    while (![circle containsPoint:p]) {
        p.x += .1;
        result.origin = p;
    }
    CGFloat w = result.size.width;
    p = result.origin;
    p.x += w;
    while (![circle containsPoint:p]) {
        w -= .1;
        result.size.width = w;
        p = result.origin;
        p.x += w;
    }
    return result;
}

грубый, но эффективный. Выглядит так:

С Swift 4 и iOS 11,NSTextContainer есть свойство под названием exclusionPaths. exclusionPaths есть следующее объявление:

массив объектов path, представляющих области, в которых текст не отображается в текстовом контейнере.

var exclusionPaths: [UIBezierPath] { get set }

кроме того, UIBezierPath есть свойство под названием usesEvenOddFillRule. usesEvenOddFillRule есть следующее объявление:

логическое значение, указывающее, является ли четно-нечетная обмотка правило используется для рисования контуров.

var usesEvenOddFillRule: Bool { get set }

С помощью usesEvenOddFillRule, вы можете создать путь исключения, окружающий круг, всего с несколькими строками кода:

var exclusionPath: UIBezierPath {
    let path = UIBezierPath(ovalIn: bounds)
    path.append(UIBezierPath(rect: bounds))
    path.usesEvenOddFillRule = true
    return path
}

далее UITextView и UIViewController подклассы показывают, как отображать текст внутри круга с помощью NSTextContainer exclusionPaths и UIBezierPath usesEvenOddFillRule свойства:

поле TextView.Свифт!--43-->

import UIKit

class TextView: UITextView {

    convenience init() {
        self.init(frame: .zero, textContainer: nil)
    }

    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)

        isScrollEnabled = false
        isEditable = false
        textContainerInset = .zero
        self.textContainer.lineBreakMode = .byTruncatingTail
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    var exclusionPath: UIBezierPath {
        let path = UIBezierPath(ovalIn: bounds)
        path.append(UIBezierPath(rect: bounds))
        path.usesEvenOddFillRule = true
        return path
    }

}

extension TextView {

    // Draw circle

    override func draw(_ rect: CGRect) {
        UIColor.orange.setFill()
        let path = UIBezierPath(ovalIn: rect)
        path.fill()
    }

    // Draw exclusion path

    /*
     override func draw(_ rect: CGRect) {
         UIColor.orange.setFill()
         exclusionPath.fill()
     }
     */

}

ViewController.Свифт!--43-->

import UIKit

class ViewController: UIViewController {

    let textView = TextView()

    override func viewDidLoad() {
        super.viewDidLoad()

        let string = "Lorem ipsum dolor sit er elit lamet, consectetaur cillium adipisicing pecu, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda."
        textView.attributedText = NSAttributedString(string: string)
        view.addSubview(textView)

        textView.translatesAutoresizingMaskIntoConstraints = false
        let horizontalConstraint = textView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        let verticalConstraint = textView.centerYAnchor.constraint(equalTo: view.centerYAnchor)
        let widthConstraint = textView.widthAnchor.constraint(equalToConstant: 240)
        let heightConstraint = textView.heightAnchor.constraint(equalToConstant: 240)
        NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])            
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        textView.textContainer.exclusionPaths = [textView.exclusionPath]
    }

}

выбирая ту или иную реализацию draw(_:), вы будете иметь следующие проявления:

вот мой вклад в вышеупомянутый вопрос в 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


}

}