在文本属性字典中实例化UIFont时出错 [英] Error when instantiating a UIFont in an text attributes dictionary

问题描述

我正在尝试设置 UIBarButtonItem 的字体，如下所示：

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)

但它会抛出一个编译错误：

But it throws a compiler error saying:

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

Cannot invoke 'init' with an argument list type '($T7, forState: UIControlState)`

我不知道是什么这意味着。我也试过了

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

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

但看来它不可分配

我该如何解决这个问题？

How can I resolve this?

推荐答案

UIFont 的初始化程序返回一个可选，因为它可能由于拼写错误的字体名称等而失败。

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

你必须打开并检查：

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

更新为Swift 3

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

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