如何在Objective-C（iOS）中的图像上写文字？

Question

我想以编程方式制作这样的图像：

我有上面的图像和文字。我应该在图像上写文字吗？

我想让它成为一个完整的.png图像（图像+标签）并将其设置为按钮的背景。

Answer 1

在图像中绘制文本并返回结果图像：+(UIImage*) drawText:(NSString*) text              inImage:(UIImage*)  image              atPoint:(CGPoint)   point {    UIFont *font = [UIFont boldSystemFontOfSize:12];    UIGraphicsBeginImageContext(image.size);    [image drawInRect:CGRectMake(0,0,image.size.width,image.size.height)];    CGRect rect = CGRectMake(point.x, point.y, image.size.width, image.size.height);    [[UIColor whiteColor] set];    [text drawInRect:CGRectIntegral(rect) withFont:font];     UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    return newImage;}用法：// note: replace "ImageUtils" with the class where you pasted the method aboveUIImage *img = [ImageUtils drawText:@"Some text"                            inImage:img                             atPoint:CGPointMake(0, 0)];将图像内部文本的原点从0,0更改为您喜欢的任何点。要在文本后面绘制纯色矩形，请在行前添加以下内容[[UIColor whiteColor] set];：[[UIColor brownColor] set];CGContextFillRect(UIGraphicsGetCurrentContext(),                   CGRectMake(0, (image.size.height-[text sizeWithFont:font].height),                                   image.size.width, image.size.height));我正在使用文本大小来计算纯色矩形的原点，但您可以用任何数字替换它。

Answer 2

我对iOS 7支持的第一个答案的贡献：+(UIImage*) drawText:(NSString*) text             inImage:(UIImage*)  image             atPoint:(CGPoint)   point{    UIGraphicsBeginImageContextWithOptions(image.size, YES, 0.0f);    [image drawInRect:CGRectMake(0,0,image.size.width,image.size.height)];    CGRect rect = CGRectMake(point.x, point.y, image.size.width, image.size.height);    [[UIColor whiteColor] set];    UIFont *font = [UIFont boldSystemFontOfSize:12];    if([text respondsToSelector:@selector(drawInRect:withAttributes:)])    {        //iOS 7        NSDictionary *att = @{NSFontAttributeName:font};        [text drawInRect:rect withAttributes:att];    }    else    {        //legacy support        [text drawInRect:CGRectIntegral(rect) withFont:font];    }    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    return newImage;}希望这可以帮助编辑：修改了UIGraphicsBeginImageContextWithOptions处理屏幕比例。

Answer 3

这是Swift版本。func textToImage(drawText: NSString, inImage: UIImage, atPoint:CGPoint)->UIImage{    // Setup the font specific variables    var textColor: UIColor = UIColor.whiteColor()    var textFont: UIFont = UIFont(name: "Helvetica Bold", size: 12)!    //Setup the image context using the passed image.    UIGraphicsBeginImageContext(inImage.size)    //Setups up 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))    // Creating a point within the space that is as bit as the image.    var rect: CGRect = CGRectMake(atPoint.x, atPoint.y, inImage.size.width, inImage.size.height)    //Now Draw the text into an image.    drawText.drawInRect(rect, withAttributes: textFontAttributes)    // Create a new image out of the images we have created    var newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()    // End the context now that we have the image we need    UIGraphicsEndImageContext()    //And pass it back up to the caller.    return newImage}要调用它，您只需传入一个图像。textToImage("000", inImage: UIImage(named:"thisImage.png")!, atPoint: CGPointMake(20, 20))以下链接帮助我顺利完成。Swift - 使用drawInRect绘制文本：withAttributes：如何在Objective-C（iOS）中的图像上写文字？最初的目标是创建一个动态图像，我可以在AnnotaionView中使用它，例如在地图上的给定位置定价，这对它来说非常有用。希望这有助于某人尝试做同样的事情。