在文本属性字典中实例化 UIFont 时出错

问题描述

我正在尝试像这样设置 UIBarButtonItem 的字体:

I'm trying to set the font of the UIBarButtonItem like so:

let barButton = UIBarButtonItem.appearance()
barButton.setTitleTextAttributes([NSFontAttributeName: UIFont(name: "AvenirNext", size: 15], forState: UIControlState.Normal)

但它抛出一个编译器错误说:

But it throws a compiler error saying:

无法使用参数列表类型 '($T7, forState: UIControlState)` 调用 'init'

我不知道那是什么意思.我也试过

and I have no idea what that means. I have also tried

barButton.titleTextAttributesForState(UIControlState.Normal) =[NSFontAttributeName...]` 

但它似乎不可分配

我该如何解决这个问题?

How can I resolve this?

推荐答案

UIFont 的初始值设定项返回一个可选项，因为它可能会因字体名称拼写错误等而失败.

The initializer of UIFont returns an optional because it may fail due to misspelled font name etc.

你必须打开它并检查:

if let font = UIFont(name: "AvenirNext", size: 15) {
    barButton.setTitleTextAttributes([NSFontAttributeName: font], forState: UIControlState.Normal)
}

针对 Swift 3 进行了更新

if let font = UIFont(name: "AvenirNext", size: 15) {
    barButton.setTitleTextAttributes([NSFontAttributeName:font], for: .normal)
}

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