如何计算特定字体和字体大小的文本字符串的宽度？

Question

我有一个显示一些字符的UILabel.像"x","y"或"rpm".如何计算标签中文本的宽度(它不是整个可用空间)？这适用于自动布局,如果UILabel内部有较小的文本,则另一个视图将具有更大的框架矩形.当指定UIFont和字体大小时,是否有方法来计算文本的宽度？也没有换行符,只有一行.

Answer 1

sizeWithFont:现已弃用,请sizeWithAttributes:改用:

UIFont *font = [UIFont fontWithName:@"Helvetica" size:30];
NSDictionary *userAttributes = @{NSFontAttributeName: font,
                                 NSForegroundColorAttributeName: [UIColor blackColor]};
NSString *text = @"hello";
...
const CGSize textSize = [text sizeWithAttributes: userAttributes];

Answer 2

由于sizeWithFont已弃用,我只是要更新我使用Swift 4和的原始答案.size

//: Playground - noun: a place where people can play

import UIKit

if let font = UIFont(name: "Helvetica", size: 24) {
   let fontAttributes = [NSAttributedStringKey.font: font]
   let myText = "Your Text Here"
   let size = (myText as NSString).size(withAttributes: fontAttributes)
}

大小应该是屏幕上的"你的文字在这里"的大小.

Answer 3

你可以通过NSString UIKit Additions中的各种sizeWithFont:方法做到这一点.在您的情况下,最简单的变体应该足够(因为您没有多行标签):

NSString *someString = @"Hello World";
UIFont *yourFont = // [UIFont ...]
CGSize stringBoundingBox = [someString sizeWithFont:yourFont];

该方法有几种变体,例如.一些人考虑换行模式或最大尺寸.

Answer 4

基于Glenn Howes的优秀答案,我创建了一个扩展来计算字符串的宽度.如果您正在执行类似设置a的宽度的操作UISegmentedControl,则可以根据段的标题字符串设置宽度.

extension String {

    func widthOfString(usingFont font: UIFont) -> CGFloat {
        let fontAttributes = [NSAttributedString.Key.font: font]
        let size = self.size(withAttributes: fontAttributes)
        return size.width
    }

    func heightOfString(usingFont font: UIFont) -> CGFloat {
        let fontAttributes = [NSAttributedString.Key.font: font]
        let size = self.size(withAttributes: fontAttributes)
        return size.height
    }

    func sizeOfString(usingFont font: UIFont) -> CGSize {
        let fontAttributes = [NSAttributedString.Key.font: font]
        return self.size(withAttributes: fontAttributes)
    }
}

用法:

    // Set width of segmentedControl
    let starString = "??"
    let starWidth = starString.widthOfString(usingFont: UIFont.systemFont(ofSize: 14)) + 16
    segmentedController.setWidth(starWidth, forSegmentAt: 3)

Answer 5

Oneliner在Swift 4.2中

let size = text.size(withAttributes:[.font: UIFont.systemFont(ofSize:18.0)])

Answer 6

斯威夫特5

使用intrinsicContentSize查找文本的高度和宽度。

yourLabel.intrinsicContentSize.width

即使您在字符串之间具有自定义的间隔（例如“ TEX T”），此方法也将起作用

Answer 7

对于斯威夫特 5.4

extension String {
    func SizeOf_String( font: UIFont) -> CGSize {
        let fontAttribute = [NSAttributedString.Key.font: font]
        let size = self.size(withAttributes: fontAttribute)  // for Single Line
       return size;
    }
}

使用它就像...

        let Str = "ABCDEF"
        let Font =  UIFont.systemFontOfSize(19.0)
        let SizeOfString = Str.SizeOfString(font: Font!)

Answer 8

Swift中的这个简单扩展效果很好。

extension String {
    func size(OfFont font: UIFont) -> CGSize {
        return (self as NSString).size(attributes: [NSFontAttributeName: font])
    }
}

用法：

let string = "hello world!"
let font = UIFont.systemFont(ofSize: 12)
let width = string.size(OfFont: font).width // size: {w: 98.912 h: 14.32}

Answer 9

如果您正在努力通过多行支持获得文本宽度，那么您可以使用下一个代码（Swift 5）：

func width(text: String, height: CGFloat) -> CGFloat {
    let attributes: [NSAttributedString.Key: Any] = [
        .font: UIFont.systemFont(ofSize: 17)
    ]
    let attributedText = NSAttributedString(string: text, attributes: attributes)
    let constraintBox = CGSize(width: .greatestFiniteMagnitude, height: height)
    let textWidth = attributedText.boundingRect(with: constraintBox, options: [.usesLineFragmentOrigin, .usesFontLeading], context: nil).width.rounded(.up)

    return textWidth
}

如果需要，您可以通过同样的方式找到文本高度（只需切换约束框实现）：

let constraintBox = CGSize(width: maxWidth, height: .greatestFiniteMagnitude)

或者这里有一个统一的函数来获得多行支持的文本大小：

func labelSize(for text: String, maxWidth: CGFloat, maxHeight: CGFloat) -> CGSize {
    let attributes: [NSAttributedString.Key: Any] = [
        .font: UIFont.systemFont(ofSize: 17)
    ]

    let attributedText = NSAttributedString(string: text, attributes: attributes)

    let constraintBox = CGSize(width: maxWidth, height: maxHeight)
    let rect = attributedText.boundingRect(with: constraintBox, options: [.usesLineFragmentOrigin, .usesFontLeading], context: nil).integral

    return rect.size
}

用法：

let textSize = labelSize(for: "SomeText", maxWidth: contentView.bounds.width, maxHeight: .greatestFiniteMagnitude)
let textHeight = textSize.height.rounded(.up)
let textWidth = textSize.width.rounded(.up)