在Swift中用纯色创建UIImage

时间：2014-10-24 05:31:56

标签： ios swift uiimage

我想以编程方式创建一个由纯色填充的UIImage。任何人都知道如何在Swift中做到这一点？

13 个答案:

答案 0 :(得分：161)

另一个很好的解决方案， Swift 2.2 兼容，就是在UIImage中创建另一个构造函数，这样：

public extension UIImage {
    public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
        let rect = CGRect(origin: .zero, size: size)
        UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
        color.setFill()
        UIRectFill(rect)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        guard let cgImage = image?.CGImage else { return nil }
        self.init(CGImage: cgImage)
    }  
}

通过这种方式，您可以通过以下方式创建自定义彩色图像：

let redImage = UIImage(color: .redColor())

或者，可选择使用自定义尺寸创建图像：

let redImage200x200 = UIImage(color: .redColor(), size: CGSize(width: 200, height: 200))

Swift 3.0 

public extension UIImage {
  public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
    let rect = CGRect(origin: .zero, size: size)
    UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
    color.setFill()
    UIRectFill(rect)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    guard let cgImage = image?.cgImage else { return nil }
    self.init(cgImage: cgImage)
  }
}

答案 1 :(得分：89)

这是另一种选择。我相信你想要一个精确的UIImage对象。

func getImageWithColor(color: UIColor, size: CGSize) -> UIImage {
    let rect = CGRectMake(0, 0, size.width, size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}

坚持使用Swift代码并将其命名为

Swift 3.1： 

func getImageWithColor(color: UIColor, size: CGSize) -> UIImage {
    let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return image
}

答案 2 :(得分：36)

Swift 4版本：

extension UIColor {
    func image(_ size: CGSize = CGSize(width: 1, height: 1)) -> UIImage {
        return UIGraphicsImageRenderer(size: size).image { rendererContext in
            self.setFill()
            rendererContext.fill(CGRect(origin: .zero, size: size))
        }
    }
}

用法：

let image0 = UIColor.orange.image(CGSize(width: 128, height: 128))
let image1 = UIColor.yellow.image()

答案 3 :(得分：14)

更简洁的方法是将逻辑封装在UIImage扩展名中：

import UIKit

extension UIImage {
  class func imageWithColor(color: UIColor) -> UIImage {
    let rect: CGRect = CGRectMake(0, 0, 1, 1)
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(1, 1), false, 0)
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
  }
}

现在，消费者可以拨打UIImage.imageWithColor(UIColor.blackColor())来创建黑色背景图片。

答案 4 :(得分：9)

class ViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        imageView.backgroundColor = UIColor.redColor()
    }
}

类似的方法，如果你想自己绘制图像而不是通过IBOutlet连接图像。

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        var frame = CGRectMake(100,100,100,100)
        var imageView2 = UIImageView(frame: frame)
        imageView2.backgroundColor = UIColor.redColor()
        self.view.addSubview(imageView2)
    }
}

从anthonyliao借来的第三种方法。更复杂一点：

class ViewController: UIViewController {

    func getImageWithColor(color: UIColor, size: CGSize) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        UIRectFill(CGRectMake(0, 0, 100, 100))
        var image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        var imageView = UIImageView(frame: CGRectMake(100,100,100,100))
        let screenImage = getImageWithColor(UIColor.redColor(), size: CGSize(width: 100, height: 100))
        imageView.image = screenImage
        self.view.addSubview(imageView)
    }
}

答案 5 :(得分：6)

您可以使用新的 iOS 10 UIGraphicsImageRenderer API。

以下是 Swift 3.1

中UIColor的扩展 
extension UIColor {
func getImage(size: CGSize) -> UIImage {
    let renderer = UIGraphicsImageRenderer(size: size)
    return renderer.image(actions: { rendererContext in
        self.setFill()
        rendererContext.fill(CGRect(x: 0, y: 0, width: size.width, height: size.height))
    })
}}

答案 6 :(得分：4)

一个很好的方法是拥有这样的计算属性：

extension UIColor {
    var imageRepresentation : UIImage {
      let rect = CGRect(x: 0.0, y: 0.0, width: 1.0, height: 1.0)
      UIGraphicsBeginImageContext(rect.size)
      let context = UIGraphicsGetCurrentContext()

      context?.setFillColor(self.cgColor)
      context?.fill(rect)

      let image = UIGraphicsGetImageFromCurrentImageContext()
      UIGraphicsEndImageContext()

    return image!
  }
}

用法：

let redImage = UIColor.red.imageRepresentation

答案 7 :(得分：3)

Swift 3版@anthonyliao接受回答：

class func getImageWithColor(color: UIColor, size: CGSize) -> UIImage
{
    let rect = CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: size.width, height: size.height))
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return image
}

答案 8 :(得分：3)

对@neoneye的出色答案进行了细微调整，允许调用代码无需创建CGSize，并且更改了名称以免与其他众多名称冲突：

快捷键4 

extension UIColor {
    func imageWithColor(width: Int, height: Int) -> UIImage {
        let size = CGSize(width: width, height: height)
        return UIGraphicsImageRenderer(size: size).image { rendererContext in
            self.setFill()
            rendererContext.fill(CGRect(origin: .zero, size: size))
        }
    }
}

答案 9 :(得分：1)

圆角的矩形

extension UIImage {
convenience init?(color: UIColor) {
    let rect = CGRect(x: 0, y: 0, width: 10, height: 2)
    UIGraphicsBeginImageContextWithOptions(CGSize(width: 10, height: 2), false, 0)
    let bezierPath = UIBezierPath(roundedRect: rect, cornerRadius: 8)
    color.setFill()
    bezierPath.fill()
    let image = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

    guard  let cgImage = image.cgImage else {
        return nil
    }
    self.init(cgImage: cgImage)
}

}

答案 10 :(得分：1)

Swift 5 / 获取非可选的 UIImage

  public static func withColor(_ color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) -> UIImage {
        let format = UIGraphicsImageRendererFormat()
        format.scale = 1
        let image =  UIGraphicsImageRenderer(size: size, format: format).image { rendererContext in
            color.setFill()
            rendererContext.fill(CGRect(origin: .zero, size: size))
        }
        return image
    }

如果需要，不要忘记使用 format.scale = 1

答案 11 :(得分：0)

我们可以使用UIGraphicsImageRenderer创建UIImage或使用传统的CGContext方法，下面是方便的初始化函数，该函数可以创建具有给定颜色的UIImage 

extension UIImage {
    /// create UIImage with color and given size
    convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1), alpha: CGFloat = 1, scale: CGFloat = 0) {
        if #available(tvOS 10.0, *) {
            let renderer = UIGraphicsImageRenderer(size: size)
            let image = renderer.image { (ctx) in
                let size = renderer.format.bounds.size
                ctx.fill(CGRect(origin: .zero, size: size))
                ctx.cgContext.setFillColor(color.cgColor)
            }
            guard let cgImage = image.cgImage else { return nil }
            self.init(cgImage: cgImage)
        } else {
            let rect = CGRect(origin: .zero, size: size)
            UIGraphicsBeginImageContextWithOptions(rect.size, false, scale)
            let context = UIGraphicsGetCurrentContext()!
            let fillColor = color.withAlphaComponent(alpha)
            context.setFillColor(fillColor.cgColor)
            context.fill(rect)
            let image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()
            guard let cgImage = image?.cgImage else { return nil }
            self.init(cgImage: cgImage)
        }
    }
}

答案 12 :(得分：0)

Swift 5, Xcode 12.4 - UIImageView 的解决方案

如果您必须像我一样处理 UIImageView，您可以选择更紧凑的解决方案，例如：exampleImageView.fill() 或 exampleImageView.fill(with: .black)。

扩展代码：

extension UIImageView {
    func fill(with color: UIColor = .lightGray) {
        let size = self.bounds.size
        let image = UIGraphicsImageRenderer(size: size).image { rendererContext in
            color.setFill()
            rendererContext.fill(CGRect(origin: .zero, size: size))
        }
        self.image = image
    }
}
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