如何为UIAlertController设置自定义字体（含按钮字体）

你之前尝试给UIAlertController设置titleTextFont的方式无效，因为这个键不属于UIAlertController，按钮的文字样式由UIAlertAction控制，下面是正确的实现方式：

核心修正点 #

移除无效的alertController.setValue(attributedOk, forKey: "titleTextFont")代码，转而给UIAlertAction设置富文本标题。

完整兼容代码（iOS 13+） #

let alertController = UIAlertController(title: NSLocalizedString(title, comment: ""), message: NSLocalizedString(newErrorMessage, comment: "") , preferredStyle: .alert)
alertController.view.tintColor = UIConfiguration.DarkGreen!

// 配置标题自定义字体
let titleFont = LanguageManager.boldFont(size: 17.0)
let attributedTitle = NSAttributedString(string: NSLocalizedString(title, comment: ""), attributes: [NSAttributedString.Key.font: titleFont])
alertController.setValue(attributedTitle, forKey: "attributedTitle")

// 配置消息文本自定义字体
let messageFont = LanguageManager.regularFont(size: 12.0)
let attributedMessage = NSAttributedString(string: NSLocalizedString(newErrorMessage, comment: ""), attributes: [NSAttributedString.Key.font: messageFont])
alertController.setValue(attributedMessage, forKey: "attributedMessage")

// 配置OK按钮自定义字体
let okTitle = NSLocalizedString("Ok", comment: "")
let okFont = LanguageManager.boldFont(size: 16.0)
let attributedOk = NSAttributedString(string: okTitle, attributes: [
    NSAttributedString.Key.font: okFont,
    NSAttributedString.Key.foregroundColor: UIConfiguration.DarkGreen! // 可选：统一按钮文字颜色与弹窗tintColor
])

let okAction = UIAlertAction(title: okTitle, style: .default, handler: nil)
okAction.setValue(attributedOk, forKey: "attributedTitle")
alertController.addAction(okAction)

present(alertController, animated: true, completion: nil)

iOS 15+ 官方API方案 #

iOS 15及以上，Apple提供了无需KVC的官方配置方式，更稳定安全：

let alertController = UIAlertController(title: NSLocalizedString(title, comment: ""), message: NSLocalizedString(newErrorMessage, comment: "") , preferredStyle: .alert)
alertController.view.tintColor = UIConfiguration.DarkGreen!

// 标题和消息配置同上，略去重复代码...

let okTitle = NSLocalizedString("Ok", comment: "")
let okFont = LanguageManager.boldFont(size: 16.0)

if #available(iOS 15.0, *) {
    var actionConfig = UIAlertAction.Configuration()
    actionConfig.titleTextAttributesTransformer = UIConfigurationTextAttributesTransformer { incomingAttrs in
        var transformedAttrs = incomingAttrs
        transformedAttrs.font = okFont
        transformedAttrs.foregroundColor = UIConfiguration.DarkGreen!
        return transformedAttrs
    }
    let okAction = UIAlertAction(title: okTitle, style: .default, handler: nil, configuration: actionConfig)
    alertController.addAction(okAction)
} else {
    // 回退到KVC方案兼容低版本
    let attributedOk = NSAttributedString(string: okTitle, attributes: [
        NSAttributedString.Key.font: okFont,
        NSAttributedString.Key.foregroundColor: UIConfiguration.DarkGreen!
    ])
    let okAction = UIAlertAction(title: okTitle, style: .default, handler: nil)
    okAction.setValue(attributedOk, forKey: "attributedTitle")
    alertController.addAction(okAction)
}

present(alertController, animated: true, completion: nil)

注意事项 #

• 低版本iOS使用KVC设置attributedTitle属于访问私有属性，但苹果审核通常不会拒绝这种常规自定义需求；
• iOS 15+优先使用官方API，避免私有属性带来的潜在适配问题。

内容的提问来源于stack exchange，提问作者Nicolas