如何在NSTextAttachment中设置模板化图像的颜色 [英] How to set color of templated image in NSTextAttachment

问题描述

如何设置作为属性字符串附件的模板化图像的颜色？

How can I set the color of a templated image that is an attachment on an attributed string?

背景：

我有一个UILabel，我将其attributionText设置为NSAttributedString。 NSAttributedString包含带有小图像的NSTextAttachment。现在我想让我的图像颜色与文本颜色匹配，我无法弄清楚如何使其工作。

I've got a UILabel and I'm setting its attributedText to an NSAttributedString. The NSAttributedString includes an NSTextAttachment with a small image. Now I want to make my image color match the text color and I can't figure out how to make it work.

我通常希望通过设置为图像着色它的渲染模式为UIImageRenderingModeAlwaysTemplate，然后在包含UIView的上设置tintColor。我已经尝试在我的UILabel上设置tintColor但是没有效果。

I would normally expect to color the image by setting its rendering mode to UIImageRenderingModeAlwaysTemplate and then setting the tintColor on the containing UIView. I've tried setting the tintColor on my UILabel but that has no effect.

这是我的代码。它在Ruby（RubyMotion）中，因此语法可能看起来有点滑稽，但它与目标C进行1：1的映射。

Here's my code. It's in Ruby (RubyMotion) so the syntax might look a little funny, but it maps 1:1 with Objective C.

attachment = NSTextAttachment.alloc.initWithData(nil, ofType: nil)
attachment.image = UIImage.imageNamed(icon_name).imageWithRenderingMode(UIImageRenderingModeAlwaysTemplate)

label_string = NSMutableAttributedString.attributedStringWithAttachment(attachment)
label_string.appendAttributedString(NSMutableAttributedString.alloc.initWithString('my text', attributes: { NSFontAttributeName => UIFont.preferredFontForTextStyle(UIFontTextStyleFootnote), NSForegroundColorAttributeName => foreground_color }))

label = UILabel.alloc.initWithFrame(CGRectZero)
label.tintColor = foreground_color
label.attributedText = label_string
label.textAlignment = NSTextAlignmentCenter
label.numberOfLines = 0

推荐答案

似乎UIKit中存在一个错误。有一个解决方法;]

It seems that there's a bug in UIKit. There's a workaround for that ;]

出于某种原因，您需要在图像附加之前附加空格，以使其与 UIImageRenderingModeAlwaysTemplate 。

For some reason you need to append empty space before image attachment to make it work properly with UIImageRenderingModeAlwaysTemplate.

所以你的片段看起来就像那样（我的是ObjC）：

So your snippet would look like that (mine is in ObjC):

- (NSAttributedString *)attributedStringWithValue:(NSString *)string image:(UIImage *)image {
    NSTextAttachment *attachment = [[NSTextAttachment alloc] init];
    attachment.image = image;

    NSAttributedString *attachmentString = [NSAttributedString attributedStringWithAttachment:attachment];
    NSMutableAttributedString *mutableAttributedString = [[NSMutableAttributedString alloc] initWithAttributedString:[[NSAttributedString alloc] initWithString:@" "]];
    [mutableAttributedString appendAttributedString:attachmentString];
    [mutableAttributedString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:0] range:NSMakeRange(0, mutableAttributedString.length)]; // Put font size 0 to prevent offset
    [mutableAttributedString addAttribute:NSForegroundColorAttributeName value:[UIColor whiteColor] range:NSMakeRange(0, mutableAttributedString.length)];
    [mutableAttributedString appendAttributedString:[[NSAttributedString alloc] initWithString:@" "]];

    NSAttributedString *ratingText = [[NSAttributedString alloc] initWithString:string];
    [mutableAttributedString appendAttributedString:ratingText];
    return mutableAttributedString;
}

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