问题描述
如何将文本转换为图像并在 UIImageview 中显示.有谁知道从文本到图像的转换?
How to convert Text to Image and show in UIImageview. Can anyone know the conversion from Text to Image?
推荐答案
使用 Swift 5 和 iOS 12，您可以选择以下6种方式中的一种来解决您的问题.
With Swift 5 and iOS 12, you can choose one the 6 following ways in order to solve your problem.
在您想将 String 转换为具有某些属性的 UIImage 的最简单情况下，您可以使用 draw(at:withAttributes:).以下 Playground 代码展示了如何使用 draw(at:withAttributes:) 从 String 获取 UIImage:
In the simplest case where you want to convert a String to a UIImage with some attributes, you can use draw(at:withAttributes:). The following Playground codes show how to get an UIImage from a String using draw(at:withAttributes:):
import UIKit
import PlaygroundSupport
let text = "Hello, world"
let attributes = [
NSAttributedString.Key.foregroundColor: UIColor.yellow,
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 22)
]
let textSize = text.size(withAttributes: attributes)
UIGraphicsBeginImageContextWithOptions(textSize, true, 0)
text.draw(at: CGPoint.zero, withAttributes: attributes)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
PlaygroundPage.current.liveView = UIImageView(image: image)
import UIKit
import PlaygroundSupport
let text = "Hello, world"
let attributes = [
NSAttributedString.Key.foregroundColor: UIColor.yellow,
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 22)
]
let textSize = text.size(withAttributes: attributes)
let renderer = UIGraphicsImageRenderer(size: textSize)
let image = renderer.image(actions: { context in
text.draw(at: CGPoint.zero, withAttributes: attributes)
})
PlaygroundPage.current.liveView = UIImageView(image: image)
请注意，NSAttributedString 有一个类似的方法，称为 draw(at:).
Note that NSAttributedString has a similar method called draw(at:).
作为 draw(at:withAttributes:) 的替代方法，您可以使用 draw(in:withAttributes:).
As an alternative to draw(at:withAttributes:), you can use draw(in:withAttributes:).
import UIKit
import PlaygroundSupport
let text = "Hello, world"
let attributes = [
NSAttributedString.Key.foregroundColor: UIColor.yellow,
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 22)
]
let textSize = text.size(withAttributes: attributes)
UIGraphicsBeginImageContextWithOptions(textSize, true, 0)
let rect = CGRect(origin: .zero, size: textSize)
text.draw(in: rect, withAttributes: attributes)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
PlaygroundPage.current.liveView = UIImageView(image: image)
import UIKit
import PlaygroundSupport
let text = "Hello, world"
let attributes = [
NSAttributedString.Key.foregroundColor: UIColor.yellow,
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 22)
]
let textSize = text.size(withAttributes: attributes)
let renderer = UIGraphicsImageRenderer(size: textSize)
let image = renderer.image(actions: { context in
let rect = CGRect(origin: .zero, size: textSize)
text.draw(in: rect, withAttributes: attributes)
})
PlaygroundPage.current.liveView = UIImageView(image: image)
请注意，NSAttributedString 有一个类似的方法，称为 draw(in:).
Note that NSAttributedString has a similar method called draw(in:).
作为 draw(at:withAttributes:) 和 draw(in:) 的替代方法，您可以使用 draw(with:options:attributes:context:).请注意，Apple 对 draw(with:options:attributes:context:):
As an alternative to draw(at:withAttributes:) and draw(in:), you can use draw(with:options:attributes:context:). Note that Apple has some recommendations for draw(with:options:attributes:context:):
此方法默认使用基线原点.如果没有指定usesLineFragmentOrigin，矩形的高度将被忽略，该操作被认为是单线渲染.
This method uses the baseline origin by default. If
usesLineFragmentOriginis not specified, the rectangle’s height will be ignored and the operation considered to be single-line rendering.
import UIKit
import PlaygroundSupport
let text = "Hello, world"
let attributes = [
NSAttributedString.Key.foregroundColor: UIColor.yellow,
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 22)
]
let textSize = text.size(withAttributes: attributes)
UIGraphicsBeginImageContextWithOptions(textSize, true, 0)
let rect = CGRect(origin: .zero, size: textSize)
text.draw(with: rect, options: [.usesLineFragmentOrigin], attributes: attributes, context: nil)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
PlaygroundPage.current.liveView = UIImageView(image: image)
import UIKit
import PlaygroundSupport
let text = "Hello, world"
let attributes = [
NSAttributedString.Key.foregroundColor: UIColor.yellow,
NSAttributedString.Key.font: UIFont.systemFont(ofSize: 22)
]
let textSize = text.size(withAttributes: attributes)
let renderer = UIGraphicsImageRenderer(size: textSize)
let image = renderer.image(actions: { context in
text.draw(with: .zero, options: [.usesLineFragmentOrigin], attributes: attributes, context: nil)
})
PlaygroundPage.current.liveView = UIImageView(image: image)
请注意，NSAttributedString 有一个类似的方法，称为 draw(with:options:context:).
Note that NSAttributedString has a similar method called draw(with:options:context:).
如果您想将 UILabel、UITextField 或 UITextView 的文本捕获到 UIImage，您可以使用 render(in:).以下 Playground 代码展示了如何使用 render(in:) 对 UILabel 的内容文本进行快照:
If you want to capture the text of a UILabel, UITextField or UITextView to a UIImage, you can use render(in:). The following Playground codes show how to snapshot the content text of a UILabel using render(in:):
import UIKit
import PlaygroundSupport
let label = UILabel(frame: .zero)
label.textColor = .yellow
label.font = UIFont.systemFont(ofSize: 22)
label.text = "Hello, world"
label.sizeToFit()
UIGraphicsBeginImageContextWithOptions(label.frame.size, true, 0)
guard let context = UIGraphicsGetCurrentContext() else { exit(0) }
label.layer.render(in: context)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
PlaygroundPage.current.liveView = UIImageView(image: image)
import UIKit
import PlaygroundSupport
let label = UILabel(frame: .zero)
label.textColor = .yellow
label.font = UIFont.systemFont(ofSize: 22)
label.text = "Hello, world"
label.sizeToFit()
let renderer = UIGraphicsImageRenderer(size: label.frame.size)
let image = renderer.image(actions: { context in
label.layer.render(in: context.cgContext)
})
PlaygroundPage.current.liveView = UIImageView(image: image)
<小时>
#5.使用 UIView 的 drawHierarchy(in:afterScreenUpdates:) 方法
如果您想将 UILabel、UITextField 或 UITextView 的文本捕获到 UIImage，您可以使用 drawHierarchy(in:afterScreenUpdates:).请注意，Apple 对 drawHierarchy(in:afterScreenUpdates:) 有一些建议:
#5. Using UIView's drawHierarchy(in:afterScreenUpdates:) method
If you want to capture the text of a UILabel, UITextField or UITextView to a UIImage, you can use drawHierarchy(in:afterScreenUpdates:). Note that Apple has some recommendations for drawHierarchy(in:afterScreenUpdates:):
当您想要将图形效果(例如模糊)应用到视图快照时，请使用此方法.此方法不如 snapshotView(afterScreenUpdates:) 方法快.
Use this method when you want to apply a graphical effect, such as a blur, to a view snapshot. This method is not as fast as the
snapshotView(afterScreenUpdates:)method.
import UIKit
import PlaygroundSupport
let label = UILabel(frame: .zero)
label.textColor = .yellow
label.font = UIFont.systemFont(ofSize: 22)
label.text = "Hello, world"
label.sizeToFit()
UIGraphicsBeginImageContextWithOptions(label.frame.size, true, 0)
_ = label.drawHierarchy(in: label.bounds, afterScreenUpdates: true)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
PlaygroundPage.current.liveView = UIImageView(image: image)
import UIKit
import PlaygroundSupport
let label = UILabel(frame: .zero)
label.textColor = .yellow
label.font = UIFont.systemFont(ofSize: 22)
label.text = "Hello, world"
label.sizeToFit()
let renderer = UIGraphicsImageRenderer(size: label.frame.size)
let image = renderer.image(actions: { context in
_ = label.drawHierarchy(in: label.bounds, afterScreenUpdates: true)
})
PlaygroundPage.current.liveView = UIImageView(image: image)
<小时>
#6.使用 UIView 的 snapshotView(afterScreenUpdates:) 方法
如果您可以从快照操作中获取 UIView 而不是 UIImage，则可以使用 snapshotView(afterScreenUpdates:).以下 Playground 代码展示了如何使用 snapshotView(afterScreenUpdates:) 将 UILabel 的内容文本快照到 UIView 中:
#6. Using UIView's snapshotView(afterScreenUpdates:) method
If it's OK for you to get a UIView instead of a UIImage from your snapshot operation, you can use snapshotView(afterScreenUpdates:). The following Playground code shows how to snapshot the content text of a UILabel into a UIView using snapshotView(afterScreenUpdates:):
import UIKit
import PlaygroundSupport
let label = UILabel(frame: .zero)
label.textColor = .yellow
label.font = UIFont.systemFont(ofSize: 22)
label.text = "Hello, world"
label.sizeToFit()
let view = label.snapshotView(afterScreenUpdates: true)
PlaygroundPage.current.liveView = view
这篇关于在 iOS 上将文本转换为图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！