Following the official docs, I created this function to calculate text height.
func calculateTextHeight(myString: String, myWidth: CGFloat, myFont: UIFont) -> CGFloat {
let textStorage = NSTextStorage(string: myString)
let textContainer = NSTextContainer(size: CGSize(width: myWidth, height: CGFloat.max))
let layoutManager = NSLayoutManager()
layoutManager.addTextContainer(textContainer)
textStorage.addLayoutManager(layoutManager)
textStorage.addAttribute(NSFontAttributeName, value: myFont, range: NSMakeRange(0, textStorage.length))
textContainer.lineFragmentPadding = 0
textContainer.lineBreakMode = .ByWordWrapping
layoutManager.glyphRangeForTextContainer(textContainer)
return layoutManager.usedRectForTextContainer(textContainer).size.height
}
But the calculated height is wrong when the text contains an emoji.
var s = "ABCDE 12345"
print(calculateTextHeight(s, myWidth: 500, myFont: UIFont.systemFontOfSize(14)))
// prints 16.7 (correct)
s = "ABCDE 12345 💩"
print(calculateTextHeight(s, myWidth: 500, myFont: UIFont.systemFontOfSize(14)))
// prints 22.9 (should be 16.7)
Is this a bug? How can I fix this?
This worked for me when text contains emojis. For NSAttributedString strings:
extension NSAttributedString {
func sizeOfString(constrainedToWidth width: Double) -> CGSize {
let framesetter = CTFramesetterCreateWithAttributedString(self)
return CTFramesetterSuggestFrameSizeWithConstraints(framesetter, CFRange(location: 0, length: 0), nil, CGSize(width: width, height: .greatestFiniteMagnitude), nil)
}
}
For String:
extension String {
func sizeOfString(constrainedToWidth width: Double, font: UIFont) -> CGSize {
let attributes = [NSAttributedString.Key.font : font]
let attString = NSAttributedString(string: self, attributes: attributes)
let framesetter = CTFramesetterCreateWithAttributedString(attString)
return CTFramesetterSuggestFrameSizeWithConstraints(framesetter, CFRange(location: 0, length: 0), nil, CGSize(width: width, height: .greatestFiniteMagnitude), nil)
}
}
I used an alternate method to calculate text height. This works with emojis.
static func calculateStringHeight(str: String, maxWidth: CGFloat, font: UIFont) -> CGFloat {
return str.boundingRectWithSize(CGSizeMake(maxWidth, CGFloat.max), options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil).height
}
I do not think it is a bug. Emoji take up more space to be displayed.
I believe this will make a difference only if the number of emoji in your text is too large.
If you try the code below, i think that the result will be the same.
s = "ABCDE 12345 💩💩💩💩💩💩💩"
print(calculateTextHeight(s, myWidth: 500, myFont: UIFont.systemFontOfSize(14)))
// prints 22.9
If you want to eliminate the emoji, you can remove them from the original text before doing the height calculation.
In this case, you need to scan the original text by replacing all emoji by other character, and then call the height calculation.
Related
Hi everyone I have created a view that shows an error message. Within this view I have inserted a UILabel that shows the message. So far so good, the height of the UILabel changes based on the length of the text using text.boundingRect
My problem is that the text is shown correctly only if it does not exceed a certain number of lines, in case the text is too long it is cut and I don't understand why
In short, if the text is not very long I have no display problems otherwise if the text is very long it is cut
this is what i am using to get the height of the text.
Where am I wrong?
private func estimateTextHeight()-> CGFloat {
let text = (toastView.textLbl.text ?? "") as NSString
let attribute: [NSAttributedString.Key: Any] = [.font: toastView.textLbl.font!]
return text.boundingRect(with: .init(width: 300, height: 2000), options: .usesLineFragmentOrigin, attributes: attribute, context: nil).height
}
private func updateToast(icon: UIImage?) -> Void {
let height = estimateTextHeight()
toastView.heightAnchor.constraint(equalToConstant: height).isActive = true
}
To calculate label height try this:
extension String {
func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
let constraintRect = CGSize(width: width,
height: .greatestFiniteMagnitude)
let boundingBox = self.boundingRect(with: constraintRect,
options: .usesLineFragmentOrigin,
attributes: [.font: font],
context: nil)
return ceil(boundingBox.height)
}
}
I want to calculate the height of my textView's in a tableView dynamically to use in heightForRowAt. I DO NOT want to use automatic dimensions as it often messes up my scrolling in containerViews.
Presently I am instantiating a textView for every cell, adding the text and getting the height using:
var textViewForCellHeight = UITextView()
textViewForCellHeight.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)
textViewForCellHeight.frame = CGRect(x: 0, y: 0, width: self.tableView.frame.size.width - cellHorizontalPadding - tableView.safeAreaInsets.left - tableView.safeAreaInsets.right, height: 0)
textViewForCellHeight.text = myString
textViewForCellHeight.sizeToFit()
return textViewForCellHeight.frame.size.height
Using this in heightForRowAt works fine and gives the correct height for the cell, but it expensive and slows down the tableView considerably. Is there a more efficient way to get the height of the tableView cell's dynamically with a textView?
You can simply pass your string in this function and you will get dynamic height according to your string.
func calculateHeight(inString:String) -> CGFloat
{
let messageString = input.text
let attributes : [NSAttributedStringKey : Any] = [NSAttributedStringKey(rawValue: NSAttributedStringKey.font.rawValue) : UIFont.systemFont(ofSize: 15.0)]
let attributedString : NSAttributedString = NSAttributedString(string: messageString!, attributes: attributes)
let rect : CGRect = attributedString.boundingRect(with: CGSize(width: 222.0, height: CGFloat.greatestFiniteMagnitude), options: .usesLineFragmentOrigin, context: nil)
let requredSize:CGRect = rect
return requiredSize.height
}
Try this code:
func cellHeight(withTxt string: String) -> Float {
let textRect: CGRect = string.boundingRect(with: CGSize(width: self.view.frame.width/* Preferred textView Width */, height: CGFloat(MAXFLOAT)), options: ([.usesLineFragmentOrigin, .usesFontLeading]), attributes: [.font: UIFont(name: "Helvetica Neue", size: 17)!], context: nil)
let requiredSize: CGSize = textRect.size
//finally u return your height
return Float(requiredSize.height)
}
I am using a kerning attribute on a UILabel to display its text with some custom letter spacing. Unfortunately, as I'm displaying user-generated strings, I sometimes see things like the following:
ie sometimes some emoji characters are not being displayed.
If I comment out the kerning but apply some paragraph style instead, I get the same kind of errored rendering.
I couldn't find anything in the documentation explicitely rejecting support for special unicode characters. Am I doing something wrong or is it an iOS bug?
The code to reproduce the bug is available as a playground here: https://github.com/Bootstragram/Playgrounds/tree/master/LabelWithEmoji.playground
and copied here:
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
extension NSAttributedString {
static func kernedSpacedText(_ text: String,
letterSpacing: CGFloat = 0.0,
lineHeight: CGFloat? = nil) -> NSAttributedString {
// TODO add the font attribute
let attributedString = NSMutableAttributedString(string: text)
attributedString.addAttribute(NSAttributedStringKey.kern,
value: letterSpacing,
range: NSRange(location: 0, length: text.count))
if let lineHeight = lineHeight {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = lineHeight
attributedString.addAttribute(NSAttributedStringKey.paragraphStyle,
value: paragraphStyle,
range: NSRange(location: 0, length: text.count))
}
return attributedString
}
}
//for familyName in UIFont.familyNames {
// for fontName in UIFont.fontNames(forFamilyName: familyName) {
// print(fontName)
// }
//}
class MyViewController : UIViewController {
override func loadView() {
let view = UIView()
view.backgroundColor = .white
let myString = "1⚽📺🍻⚾️🌯🏄♂️👍\n2 😀💿💸 🍻"
let label = UILabel()
label.frame = CGRect(x: 150, y: 200, width: 200, height: 100)
label.attributedText = NSAttributedString.kernedSpacedText(myString)
label.numberOfLines = 0
label.textColor = .black
view.addSubview(label)
self.view = view
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()
Thanks.
TL, DR:
String.count != NSString.length. Any time you see NSRange, you must convert your String into UTF-16:
static func kernedSpacedText(_ text: String,
letterSpacing: CGFloat = 0.0,
lineHeight: CGFloat? = nil) -> NSAttributedString {
// TODO add the font attribute
let attributedString = NSMutableAttributedString(string: text)
attributedString.addAttribute(NSAttributedStringKey.kern,
value: letterSpacing,
range: NSRange(location: 0, length: text.utf16.count))
if let lineHeight = lineHeight {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = lineHeight
attributedString.addAttribute(NSAttributedStringKey.paragraphStyle,
value: paragraphStyle,
range: NSRange(location: 0, length: text.utf16.count))
}
return attributedString
}
The longer explanation
Yours is a common problem converting between Swift's String and ObjC's NSString. The length of a String is the number of extended grapheme clusters; in ObjC, it's the number of UTF-16 code points needed to encode that string.
Take the thumb-up character for example:
let str = "👍"
let nsStr = str as NSString
print(str.count) // 1
print(nsStr.length) // 2
Things can get even weirder when it comes to the flag emojis:
let str = "🇺🇸"
let nsStr = str as NSString
print(str.count) // 1
print(nsStr.length) // 4
Even though this article was written all the way back in 2003, it's still a good read today:
The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets.
I'm trying to set a tableViewCell height equal to the height of the attributedString inside the cell. However whatever I do it does not seem to have the correctSize. this is what I've tried so far
cellHeight
//Convert description to NSAttributedString and get height
//width is equal to screen width - right and left offset
//at the end add the bottom and height offset to the cell height
return detailPetViewModel!.description
.lineSpacing(spacing: 4)
.heightWithConstrainedWidth(width: Sizes.screenWidth - 40) + 10
Customize descLabel in cell subclass
//Customize descLabel
descLabel.font = FontFamily.Avenir.Regular.font(size: 16)
descLabel.textColor = UIColor(named: .SecondaryTextColor)
//Multiple lines
descLabel.numberOfLines = 0
descLabel.lineBreakMode = .byWordWrapping
descLabel.sizeToFit()
linespacing extension
extension String {
func lineSpacing(spacing: CGFloat) -> NSAttributedString {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.lineSpacing = spacing
let attributedString = NSMutableAttributedString(string: self)
attributedString.addAttribute(NSParagraphStyleAttributeName, value:paragraphStyle, range:NSMakeRange(0, attributedString.length))
return attributedString
}
}
height Extension
extension NSAttributedString {
func heightWithConstrainedWidth(width: CGFloat) -> CGFloat {
let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)
return boundingBox.height
}
}
This is the extension I use. You shouldn't have to pass in any information about the font or line-height as the attributed string already knowns its values.
extension NSAttributedString {
func height(containerWidth: CGFloat) -> CGFloat {
let rect = self.boundingRect(with: CGSize.init(width: containerWidth, height: CGFloat.greatestFiniteMagnitude),
options: [.usesLineFragmentOrigin, .usesFontLeading],
context: nil)
return ceil(rect.size.height)
}
func width(containerHeight: CGFloat) -> CGFloat {
let rect = self.boundingRect(with: CGSize.init(width: CGFloat.greatestFiniteMagnitude, height: containerHeight),
options: [.usesLineFragmentOrigin, .usesFontLeading],
context: nil)
return ceil(rect.size.width)
}
}
Used like this:
let height = detailPetViewModel!.description.height(containerWidth: Sizes.screenWidth - 40 + 10)
You can simply use (the instance of NSAttributedString).size.height
e.g.
let a = NSAttributedString(string: "A string", attributes: [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 14)])
let height = a.size().height
im trying to calculate the height of a UILabel with LineSpacing attribute. The weird thing is that calculated value of the height of the normal label.text is lower then the label.attributedText with its lineheight. it looks like i'm doing something wrong, but cant find what, so please help :D.
The provided code is specially made for SO to make it compact and clear, it is implemented differently in my project.
extension NSAttributedString {
func heightWithWidth(width: CGFloat) -> CGFloat {
let maxSize = CGSize(width: width, height: CGFloat.max)
let boundingBox = self.boundingRectWithSize(maxSize, options: [.UsesLineFragmentOrigin, .UsesFontLeading, .UsesDeviceMetrics], context: nil)
return boundingBox.height
}
}
extension UILabel {
func getHeightWithGivenWidthAndLineHeight(lineHeight: CGFloat, labelWidth: CGFloat) -> CGFloat {
let text = self.text
if let text = text {
let attributeString = NSMutableAttributedString(string: text)
let style = NSMutableParagraphStyle()
style.lineSpacing = lineHeight
attributeString.addAttribute(NSParagraphStyleAttributeName, value: style, range: NSMakeRange(0, text.characters.count))
let height = attributeString.heightWithWidth(labelWidth)
self.attributedText = attributeString
return height
}
return 0
}
I call this by
let contentHeight = contentLabel.text! == "" ? 0 : contentLabel.getHeightWithGivenWidthAndLineHeight(3, labelWidth: labelWidth)
Working with normal strings (without spacing) works perfectly, when i use attributedstring with lineSpacing it fails to calculate the correct value.
You can just use UILabel's sizeThatFits. For example:
let text = "This is\nSome\nGreat\nText"
let contentHeight = contentLabel.text! == "" ? 0 : contentLabel.getHeightWidthGivenWidthAndLineHeight(6, labelWidth: labelWidth)
//returns 73.2
But just setting
contentLabel.attributedText = contentLabel.attributedString //attributedString is same as getHeightWidthGivenWidthAndLineHeight
let size = contentLabel.sizeThatFits(contentLabel.frame.size)
//returns (w 49.5,h 99.5)
Code for attributedString added to your extension, if you need to see that:
var attributedString:NSAttributedString?{
if let text = self.text{
let attributeString = NSMutableAttributedString(string: text)
let style = NSMutableParagraphStyle()
style.lineSpacing = 6
attributeString.addAttribute(NSParagraphStyleAttributeName, value: style, range: NSMakeRange(0, text.characters.count))
return attributeString
}
return nil
}
I updated my Extension this way to set the line height and return the new label height at the same time. Thanx to beyowulf
extension UILabel {
func setLineHeight(lineHeight: CGFloat, labelWidth: CGFloat) -> CGFloat {
let text = self.text
if let text = text {
let attributeString = NSMutableAttributedString(string: text)
let style = NSMutableParagraphStyle()
style.lineSpacing = lineHeight
attributeString.addAttribute(NSParagraphStyleAttributeName, value: style, range: NSMakeRange(0, text.characters.count))
self.attributedText = attributeString
return self.sizeThatFits(CGSize(width: labelWidth, height: 20)).height
}
return 0
}
}