Ios 如何在uiimage的中心绘制文本？

我想将我的文本售罄设置为UIimage中的中间位置。但它不在中心

func textToImage(drawText text: NSString, inImage image: UIImage, atPoint point: CGPoint) -> UIImage {

    let textColor = UIColor.white
    let textFont = UIFont(name: "Helvetica Bold", size: 32)!

    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)
    let rect = CGRect(origin: CGPoint(x:(image.size.width/2), y: (image.size.height/2)), size: image.size)

    text.draw(in: rect, withAttributes: textFontAttributes)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage!
}

调用函数

 imageViewSoldStatus.image = textToImage(drawText: "Sold out", inImage: UIImage(named:"soldout.png")!, atPoint: CGPoint(x: 5.0, y: 5.0))

我花了很长时间来解决这个问题，但我找不到任何解决办法

红色标记我的图像

上面是我得到的屏幕。下面是我想要实现的设计

更新

玛丽·德·安斯沃德用过！它是文本对齐中心，但不是图像中心

试试这个：

func textToImage(drawText text: NSString, inImage image: UIImage) -> UIImage? {
    //draw image first
    UIGraphicsBeginImageContext(image.size)
    image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
    
    //text attributes
    let font=UIFont(name: "Helvetica-Bold", size: 32)!
    let text_style=NSMutableParagraphStyle()
    text_style.alignment=NSTextAlignment.center
    let text_color=UIColor.white
    let attributes=[NSFontAttributeName:font, NSParagraphStyleAttributeName:text_style, NSForegroundColorAttributeName:text_color]

    //vertically center (depending on font)
    let text_h=font.lineHeight
    let text_y=(image.size.height-text_h)/2
    let text_rect=CGRect(x: 0, y: text_y, width: image.size.width, height: text_h)
    text.draw(in: text_rect.integral, withAttributes: attributes)
    let result=UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return result
}

---

玛丽的答案更新为swift 4

func textToImage(drawText text: NSString, inImage image: UIImage) -> UIImage {
        UIGraphicsBeginImageContext(image.size)
        image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
        let font=UIFont(name: "Helvetica-Bold", size: 14)!
        let text_style=NSMutableParagraphStyle()
        text_style.alignment=NSTextAlignment.center
        let text_color=UIColor.white
        let attributes=[NSAttributedStringKey.font:font, NSAttributedStringKey.paragraphStyle:text_style, NSAttributedStringKey.foregroundColor:text_color]
        let text_h=font.lineHeight
        let text_y=(image.size.height-text_h)/2
        let text_rect=CGRect(x: 0, y: text_y, width: image.size.width, height: text_h)
        text.draw(in: text_rect.integral, withAttributes: attributes)
        let result=UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return result!
    }

更新为Swift 5

func textToImage(drawText text: NSString, inImage image: UIImage) -> UIImage {
    UIGraphicsBeginImageContext(image.size)
    image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
    let font=UIFont(name: "Helvetica-Bold", size: 14)!
    let text_style=NSMutableParagraphStyle()
    text_style.alignment=NSTextAlignment.center
    let text_color=UIColor.white
    let attributes=[NSAttributedString.Key.font:font, NSAttributedString.Key.paragraphStyle:text_style, NSAttributedString.Key.foregroundColor:text_color]
    let text_h=font.lineHeight
    let text_y=(image.size.height-text_h)/2
    let text_rect=CGRect(x: 0, y: text_y, width: image.size.width, height: text_h)
    text.draw(in: text_rect.integral, withAttributes: attributes)
    let result=UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return result!
}

---

我在哪里找到的尺寸？你可能应该使用image.size。我将编辑我的答案。你的图像是红旗还是黑色矩形？红旗是我的图像然后文本的宽度应该是图像的宽度，以便居中。我更新我的答案。