1. 在Android中使用Typeface来设置字体，并使用SpannableString对象来设置粗体效果。示例如下：

Typeface customTypeface = Typeface.createFromAsset(getAssets(),"custom_font.ttf");
String htmlString = "Some bold text in custom font";
SpannableString spannableString = new SpannableString(Html.fromHtml(htmlString));
spannableString.setSpan(new StyleSpan(customTypeface.getStyle()), 0, spannableString.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
textView.setText(spannableString);

2. 在iOS中使用NSAttributedString来设置字体样式，并使用UIFontDescriptor和UIFont中的方法来设置自定义字体的粗体效果。示例如下：

NSString *htmlString = @"Some bold text in custom font";
NSAttributedString *attributedString = [[NSAttributedString alloc] initWithData:[htmlString dataUsingEncoding:NSUnicodeStringEncoding] options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType} documentAttributes:nil error:nil];
UIFontDescriptor *fontDescriptor = [UIFontDescriptor fontDescriptorWithName:@"CustomFont" size:16.0];
UIFontDescriptor *boldFontDescriptor = [fontDescriptor fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitBold];
UIFont *boldCustomFont = [UIFont fontWithDescriptor:boldFontDescriptor size:0.0];
NSMutableAttributedString *mutableAttributedString = [[NSMutableAttributedString alloc] initWithAttributedString:attributedString];
[mutableAttributedString addAttribute:NSFontAttributeName value:boldCustomFont range:NSMakeRange(0, mutableAttributedString.length)];
textView.attributedText = mutableAttributedString;