在 Swift 中创建纯色的 UIImage

我想以编程方式创建一个由纯色填充的 UIImage。有人知道在 Swift 里怎么做吗？

121793 次浏览
小开 
class ViewController: UIViewController {


@IBOutlet weak var imageView: UIImageView!


override func viewDidLoad() {
super.viewDidLoad()


imageView.backgroundColor = UIColor.redColor()
}
}

类似的方法，如果你想绘制的图像自己与连接一个通过 IBOutlet。

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)
}
}

第三种方法借鉴了 Anthony liao，稍微复杂一点:

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)
}
}
小开

还有一个选择，我相信您想要一个精确的 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
}

把这个放到你的 Swift 代码里，然后调用它

迅捷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
}
小开

更简洁的方法是将逻辑封装在 UIImage扩展中:

import UIKit


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

现在消费者可以调用 UIImage.imageWithColor(UIColor.blackColor())来创建一个具有黑色背景的图像。

小开
最佳答案

另一个不错的解决办法, Swift 3.0

    public extension UIImage {
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)
}
}

Swift 2.2 兼容，是在 UIImage 中创建另一个构造函数，如下所示:

    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，您可以创建自定义彩色图像，如下所示:

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

或者，可以选择创建自定义大小的图像:

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

Swift 3 version of@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
}
小开

您可以使用新的 IOS10 UIGraphicsImageRenderer API。

这是 Swift 3.1中 UIColor 的一个扩展

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))
})
}}
小开

一个不错的方法是使用这样的计算属性:

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
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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()
小开

一个微小的调整,@neweye 的出色的答案，允许调用代码不需要创建 CGSize，并改变了名称，以免与许多其他名称发生冲突:

Swift 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))
}
}
}
小开

圆角的直角

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)
}
}
小开

我们可以使用 UIGraphicsImageRenderer 来创建 UIImage，也可以使用传统的 CGContext 方法，下面是方便的 init 函数，它可以创建给定颜色的 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)
}
}
}
小开

Swift 5 /< strong > 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 form.scale = 1

小开

Swift 5，Xcode 12.4-UIImageView 的解决方案

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

分机代码:

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
}
}
小开

如果您的应用程序支持 iOS10或更高版本，我们应该使用 UIGraphicsImageRenderer，因为它是 再快点。

下面是 UIImage扩展中的一些静态方法/init 方法(可选 UIImage) :

import UIKit


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


static func from(color: UIColor, size: CGFloat = 1) -> UIImage {
return from(color: color, size: CGSize(width: size, height: size))
}


static func from(color: UIColor) -> UIImage {
return from(color: color, size: 1)
}


convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
let format = UIGraphicsImageRendererFormat()
format.scale = 1
let image = UIGraphicsImageRenderer(size: size, format: format).image { context in
color.setFill()
context.fill(CGRect(origin: .zero, size: size))
}
guard let cgImage = image.cgImage else { return nil }
self.init(cgImage: cgImage)
}


convenience init?(color: UIColor, size: CGFloat = 1) {
self.init(color: color, size: CGSize(width: size, height: size))
}


convenience init?(color: UIColor) {
self.init(color: color, size: 1)
}
}


struct Example {
func createAnImageWithColorRed() {
UIImage(color: .red, size: CGSize(width: 10, height: 10))
UIImage(color: .red, size: 10)
UIImage(color: .red)


UIImage.from(color: .red, size: CGSize(width: 10, height: 10))
UIImage.from(color: .red, size: 10)
UIImage.from(color: .red)
}
}

预览:

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