Как добавить текст к изображению в iOS Swift?

82

Я огляделся и не смог понять, как взять текст, наложить его на изображение, а затем объединить два в одно UIImage.

Я исчерпал Google, используя поисковые запросы, которые я могу придумать, поэтому, если у кого-то есть решение или, по крайней мере, подсказка, на которую они могут указать, были бы очень признательны.

ios  swift  uiimage 
— Кристофер Уэйд Кэнтли
источник

Ответы:

186

Хорошо ... Разобрался:

func textToImage(drawText: NSString, inImage: UIImage, atPoint: CGPoint) -> UIImage{

    // Setup the font specific variables
    var textColor = UIColor.whiteColor()
    var textFont = UIFont(name: "Helvetica Bold", size: 12)!

    // Setup the image context using the passed image
    let scale = UIScreen.mainScreen().scale
    UIGraphicsBeginImageContextWithOptions(inImage.size, false, scale)

    // Setup the font attributes that will be later used to dictate how the text should be drawn
    let textFontAttributes = [
        NSFontAttributeName: textFont,
        NSForegroundColorAttributeName: textColor,
    ]

    // Put the image into a rectangle as large as the original image
    inImage.drawInRect(CGRectMake(0, 0, inImage.size.width, inImage.size.height))

    // Create a point within the space that is as bit as the image
    var rect = CGRectMake(atPoint.x, atPoint.y, inImage.size.width, inImage.size.height)

    // Draw the text into an image
    drawText.drawInRect(rect, withAttributes: textFontAttributes)

    // Create a new image out of the images we have created
    var newImage = UIGraphicsGetImageFromCurrentImageContext()

    // End the context now that we have the image we need
    UIGraphicsEndImageContext()

    //Pass the image back up to the caller
    return newImage

}

Чтобы вызвать это, вы просто передаете изображение:

textToImage("000", inImage: UIImage(named:"thisImage.png")!, atPoint: CGPointMake(20, 20))

Следующие ссылки помогли мне понять это:

Swift - Рисование текста с помощью drawInRect: withAttributes:

Как написать текст на изображении в Objective-C (iOS)?

Первоначальной целью было создать динамическое изображение, которое я мог бы использовать, AnnotaionViewнапример, для указания цены в заданном месте на карте, и это отлично сработало. Надеюсь, это поможет кому-то, кто пытается сделать то же самое.

Для Swift 3:

 func textToImage(drawText text: NSString, inImage image: UIImage, atPoint point: CGPoint) -> UIImage {
    let textColor = UIColor.white
    let textFont = UIFont(name: "Helvetica Bold", size: 12)!

    let scale = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(image.size, false, scale)

    let textFontAttributes = [
        NSFontAttributeName: textFont,
        NSForegroundColorAttributeName: textColor,
        ] as [String : Any]
    image.draw(in: CGRect(origin: CGPoint.zero, size: image.size))

    let rect = CGRect(origin: point, size: image.size)
    text.draw(in: rect, withAttributes: textFontAttributes)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
 }

Для Swift 4:

 func textToImage(drawText text: String, inImage image: UIImage, atPoint point: CGPoint) -> UIImage {
    let textColor = UIColor.white
    let textFont = UIFont(name: "Helvetica Bold", size: 12)!

    let scale = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(image.size, false, scale)

    let textFontAttributes = [
        NSAttributedStringKey.font: textFont,
        NSAttributedStringKey.foregroundColor: textColor,
        ] as [NSAttributedStringKey : Any]
    image.draw(in: CGRect(origin: CGPoint.zero, size: image.size))

    let rect = CGRect(origin: point, size: image.size)
    text.draw(in: rect, withAttributes: textFontAttributes)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
 }

Для Swift 5:

func textToImage(drawText text: String, inImage image: UIImage, atPoint point: CGPoint) -> UIImage {
    let textColor = UIColor.white
    let textFont = UIFont(name: "Helvetica Bold", size: 12)!

    let scale = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(image.size, false, scale)

    let textFontAttributes = [
        NSAttributedString.Key.font: textFont,
        NSAttributedString.Key.foregroundColor: textColor,
        ] as [NSAttributedString.Key : Any]
    image.draw(in: CGRect(origin: CGPoint.zero, size: image.size))

    let rect = CGRect(origin: point, size: image.size)
    text.draw(in: rect, withAttributes: textFontAttributes)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
}
— Christopher Wade Cantley
источник
1
superhelpful! thanks for posting your code. and so well commented.
— Aspen
can those texts or their container rects response to tap events?
— PPrasai
1
@JadeSync if the object you are importing the image into is clickable, then yes. But it isn't the text that is clickable, it is the container the final images is used within that would need to be clickable. In fact, that is what I did with this image because I needed a way to have a clickable marker on a map, and the marker needed to have text in an image. The marker has a click event delegate so it isn't the image they are clicking on but the marker that contains it.
— Christopher Wade Cantley
2
If i set the point to the bottom right of the image and the text is too long it extends off the image. Any suggestions on how to get the text to align to the left of the point instead of extending off of the image to the right?
— chickenparm
I ran into that issue as well and frankly, it depends on the font type and size, and the size of the image, where you want the text to start in the image since you may not want to step on a PNG shadow. This was a trial-&-error thing that require me adding a character, figuring out how many pixels to move the start point to get it in, then do a quick calculation to figure the sliding start point based on the number of characters (up to a max based on how it looks). I didn't want to get too complicated, so I addressed the bare solution for my question.
— Christopher Wade Cantley
20

My simple solution:

func generateImageWithText(text: String) -> UIImage? {
    let image = UIImage(named: "imageWithoutText")!

    let imageView = UIImageView(image: image)
    imageView.backgroundColor = UIColor.clear
    imageView.frame = CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height)

    let label = UILabel(frame: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
    label.backgroundColor = UIColor.clear
    label.textAlignment = .center
    label.textColor = UIColor.white
    label.text = text

    UIGraphicsBeginImageContextWithOptions(label.bounds.size, false, 0)
    imageView.layer.render(in: UIGraphicsGetCurrentContext()!)
    label.layer.render(in: UIGraphicsGetCurrentContext()!)
    let imageWithText = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return imageWithText
}
— Darkngs
источник
Thaks for code but how to adjust font size, every image size is different with different text length. How can I make this dynamic.
— iPhoneDev
I think you should use Autoshrink. Set max font size for max width of label and add: label.adjustsFontSizeToFitWidth = true & label.minimumScaleFactor = 0.5
— Darkngs
is there a way to add label text aligned to any of corners?
— Ashh
11

You can also do a CATextLayer.

    // 1
let textLayer = CATextLayer()
textLayer.frame = someView.bounds

// 2
let string = String(
  repeating: "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce auctor arcu quis velit congue dictum. ", 
  count: 20
)

textLayer.string = string

// 3
let fontName: CFStringRef = "Noteworthy-Light"
textLayer.font = CTFontCreateWithName(fontName, fontSize, nil)

// 4
textLayer.foregroundColor = UIColor.darkGray.cgColor
textLayer.isWrapped = true
textLayer.alignmentMode = kCAAlignmentLeft
textLayer.contentsScale = UIScreen.main.scale
someView.layer.addSublayer(textLayer)

https://www.raywenderlich.com/402-calayer-tutorial-for-ios-getting-started

— Aspen
источник
1
Love Ray's stuff. Thanks for the alternative method!
— Christopher Wade Cantley
2
Your adding a text layer to a view here, not to an image
— brainray
1
Worth mentioning if one is looking to vertically align the text see stackoverflow.com/questions/4765461/…
— JKRT
5

I have created an extension for using it everywhere :

import Foundation
import UIKit
extension UIImage {

    class func createImageWithLabelOverlay(label: UILabel,imageSize: CGSize, image: UIImage) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(CGSize(width: imageSize.width, height: imageSize.height), false, 2.0)
        let currentView = UIView.init(frame: CGRect(x: 0, y: 0, width: imageSize.width, height: imageSize.height))
        let currentImage = UIImageView.init(image: image)
        currentImage.frame = CGRect(x: 0, y: 0, width: imageSize.width, height: imageSize.height)
        currentView.addSubview(currentImage)
        currentView.addSubview(label)
        currentView.layer.render(in: UIGraphicsGetCurrentContext()!)
        let img = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return img!
    }

}

Usage : Anywhere on your ViewController where you have the size and the label to add use it as follows - 

let newImageWithOverlay = UIImage.createImageWithLabelOverlay(label: labelToAdd, imageSize: size, image: editedImage)
— Ankit Kumar Gupta
источник
1
Awesome! Thanks for contributing this.
— Christopher Wade Cantley
It shows white background even if I used transparent image
— EI Captain v2.0
What are you doing putting it on a view or uploading to server?
— Ankit Kumar Gupta
Just take the image and shows it in image view. It shows white background
— EI Captain v2.0
Your image view and its superview must have clear background. If you post it to server in png format then it will be as you want. Do that and check. Or try saving it locally once.
— Ankit Kumar Gupta
3

For swift 4: 

func textToImage(drawText text: NSString, inImage image: UIImage, atPoint point: CGPoint) -> UIImage {


    let scale = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(image.size, false, scale)

    image.draw(in: CGRect(origin: CGPoint.zero, size: image.size))

    let rect = CGRect(origin: point, size: image.size)

    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.alignment = .center



    let attrs = [NSAttributedStringKey.font: UIFont(name: "Helvetica Bold", size: 12)!,NSAttributedStringKey.foregroundColor : UIColor.white , NSAttributedStringKey.paragraphStyle: paragraphStyle]


    text.draw(with: rect, options: .usesLineFragmentOrigin, attributes: attrs, context: nil)



    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
}
— Yasin Aktimur
источник
1

I can't see anything in your initial question suggesting that this must be done exclusively in code - so why not simply add a UILabel in interface builder, and add constraints to give it the same length and width as your image, center it vertically and horizontally (or however you need it placed), delete the label text, set the text font, size, colour, etc. as needed (including ticking Autoshrink with whatever minimum size or scale you need), and ensure it's background is transparent.

Then just connect it to an IBOutlet, and set the text in code as needed (e.g. in viewWillAppear, or by using a ViewModel approach and setting it on initialisation of your view/viewcontroller).

— Gsp
источник
0

I have tried this basic components. Hope it will work.

func imageWithText(image : UIImage, text : String) -> UIImage {

        let outerView = UIView(frame: CGRect(x: 0, y: 0, width: image.size.width / 2, height: image.size.height / 2))
        let imgView = UIImageView(frame: CGRect(x: 0, y: 0, width: outerView.frame.width, height: outerView.frame.height))
        imgView.image = image
        outerView.addSubview(imgView)

        let lbl = UILabel(frame: CGRect(x: 5, y: 5, width: outerView.frame.width, height: 200))
        lbl.font = UIFont(name: "HelveticaNeue-Bold", size: 70)
        lbl.text = text
        lbl.textAlignment = .left
        lbl.textColor = UIColor.blue

        outerView.addSubview(lbl)

        let renderer = UIGraphicsImageRenderer(size: outerView.bounds.size)
        let convertedImage = renderer.image { ctx in
            outerView.drawHierarchy(in: outerView.bounds, afterScreenUpdates: true)

        }
        return convertedImage
    }
— Muhammad Haroon Iqbal
источник
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