How to generate an UIImage from custom text in Swift - ios

Question

I am trying to generate an UIImage from custom text in Swift3.
Using iOS Controls, It's possible to create an UIImage, below is the code:
class func imageWithText(txtField: UITextField) -> UIImage {
UIGraphicsBeginImageContextWithOptions(txtField.bounds.size, false, 0.0)
txtField.layer.render(in: UIGraphicsGetCurrentContext()!)
let img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return img!
}
Note: I know it's also possible to add some text to an image, but I don't want to do like this.
Can someone help me to resolve this? Thank you!

Answer 1

Here is a String extension that can be used as shown below to create UIImage instances from a String instance, without the need for UI controls like UITextField or UILabel:
var image: UIImage? =
"Test".image(withAttributes: [
.foregroundColor: UIColor.red,
.font: UIFont.systemFont(ofSize: 30.0),
], size: CGSize(width: 300.0, height: 80.0))
// Or
image = "Test".image(withAttributes: [.font: UIFont.systemFont(ofSize: 80.0)])
// Or
image = "Test".image(size: CGSize(width: 300.0, height: 80.0))
// Or even just
image = "Test".image()
Below are two possible implementations for achieving the desired effect demonstrated above:
UIGraphicsImageRenderer Method (more performant and recommended implementation by Apple)
extension String {
/// Generates a `UIImage` instance from this string using a specified
/// attributes and size.
///
/// - Parameters:
/// - attributes: to draw this string with. Default is `nil`.
/// - size: of the image to return.
/// - Returns: a `UIImage` instance from this string using a specified
/// attributes and size, or `nil` if the operation fails.
func image(withAttributes attributes: [NSAttributedString.Key: Any]? = nil, size: CGSize? = nil) -> UIImage? {
let size = size ?? (self as NSString).size(withAttributes: attributes)
return UIGraphicsImageRenderer(size: size).image { _ in
(self as NSString).draw(in: CGRect(origin: .zero, size: size),
withAttributes: attributes)
}
}
}
UIGraphicsImageContext Method (old-school; included for thoroughness)
extension String {
/// Generates a `UIImage` instance from this string using a specified
/// attributes and size.
///
/// - Parameters:
/// - attributes: to draw this string with. Default is `nil`.
/// - size: of the image to return.
/// - Returns: a `UIImage` instance from this string using a specified
/// attributes and size, or `nil` if the operation fails.
func image(withAttributes attributes: [NSAttributedString.Key: Any]? = nil, size: CGSize? = nil) -> UIImage? {
let size = size ?? (self as NSString).size(withAttributes: attributes)
UIGraphicsBeginImageContext(size)
(self as NSString).draw(in: CGRect(origin: .zero, size: size),
withAttributes: attributes)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}

Answer 2

You can use this function, you can send any text to this function, inside it i create UILabel and set text attribute as you like
func imageWith(name: String?) -> UIImage? {
let frame = CGRect(x: 0, y: 0, width: 100, height: 100)
let nameLabel = UILabel(frame: frame)
nameLabel.textAlignment = .center
nameLabel.backgroundColor = .lightGray
nameLabel.textColor = .white
nameLabel.font = UIFont.boldSystemFont(ofSize: 40)
nameLabel.text = name
UIGraphicsBeginImageContext(frame.size)
if let currentContext = UIGraphicsGetCurrentContext() {
nameLabel.layer.render(in: currentContext)
let nameImage = UIGraphicsGetImageFromCurrentImageContext()
return nameImage
}
return nil
}