如何在Objective-C（iOS）的图像上写文本？

我想以编程方式制作这样的图像：

我有上面的图像和文字与我。我应该在图像上写文字吗？

我想使它成为一个完整的PNG图像（图像+标签），并将其设置为button的背景。

请提供任何示例代码或任何build议。

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 above UIImage *img = [ImageUtils drawText:@"Some text" inImage:img atPoint:CGPointMake(0, 0)];

将图像内的文字原点从0,0改为任何你喜欢的点。

要在文本后面绘制纯色矩形，请在[[UIColor whiteColor] set];行之前添加以下内容[[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，但可以用任何数字replace它。

我对iOS 7支持的第一个答案的贡献是：

 +(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UIGraphicsBeginImageContextWithOptions来处理屏幕比例。 Thk @SoftDesigner

仅限iOS7。

水印在右下angular。

 @interface UIImage (DrawWatermarkText) -(UIImage*)drawWatermarkText:(NSString*)text; @end @implementation UIImage (DrawWatermarkText) -(UIImage*)drawWatermarkText:(NSString*)text { UIColor *textColor = [UIColor colorWithWhite:0.5 alpha:1.0]; UIFont *font = [UIFont systemFontOfSize:50]; CGFloat paddingX = 20.f; CGFloat paddingY = 20.f; // Compute rect to draw the text inside CGSize imageSize = self.size; NSDictionary *attr = @{NSForegroundColorAttributeName: textColor, NSFontAttributeName: font}; CGSize textSize = [text sizeWithAttributes:attr]; CGRect textRect = CGRectMake(imageSize.width - textSize.width - paddingX, imageSize.height - textSize.height - paddingY, textSize.width, textSize.height); // Create the image UIGraphicsBeginImageContext(imageSize); [self drawInRect:CGRectMake(0, 0, imageSize.width, imageSize.height)]; [text drawInRect:CGRectIntegral(textRect) withAttributes:attr]; UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return resultImage; } @end

用法：

 UIImage *image = [UIImage imageNamed:@"mona_lisa"]; image = [image drawWatermarkText:@"Leonardo da Vinci"];

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 }