好吧…我知道了：

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}

要调用它，您只需传递一个图像：

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

最初的目标是创建一个动态图像，我可以在其中使用该图像，

AnnotaionView

对于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! }

对于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! }

对于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!}