我尝试了两种方法:
方法一:
label.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)
label.adjustsFontForContentSizeCategory = true
这很好用,即使在“设置”中更改了首选文本大小,文本大小也会自动更改,甚至在我返回应用程序之前。但它只适用于系统字体(旧金山)。
方法二:
要使用自定义字体,我添加了一个扩展名UIFontDescriptor
:
//from this answer http://stackoverflow.com/a/35467158/2907715
extension UIFontDescriptor {
private struct SubStruct {
static var preferredFontName: String = "Avenir-medium"
}
static let fontSizeTable : NSDictionary = [
UIFontTextStyle.headline: [
UIContentSizeCategory.accessibilityExtraExtraExtraLarge: 23,
UIContentSizeCategory.accessibilityExtraExtraLarge: 23,
UIContentSizeCategory.accessibilityExtraLarge: 23,
UIContentSizeCategory.accessibilityLarge: 23,
UIContentSizeCategory.accessibilityMedium: 23,
UIContentSizeCategory.extraExtraExtraLarge: 23,
UIContentSizeCategory.extraExtraLarge: 21,
UIContentSizeCategory.extraLarge: 19,
UIContentSizeCategory.large: 17,
UIContentSizeCategory.medium: 16,
UIContentSizeCategory.small: 15,
UIContentSizeCategory.extraSmall: 14
],
UIFontTextStyle.subheadline: [
UIContentSizeCategory.accessibilityExtraExtraExtraLarge: 21,
UIContentSizeCategory.accessibilityExtraExtraLarge: 21,
UIContentSizeCategory.accessibilityExtraLarge: 21,
UIContentSizeCategory.accessibilityLarge: 21,
UIContentSizeCategory.accessibilityMedium: 21,
UIContentSizeCategory.extraExtraExtraLarge: 21,
UIContentSizeCategory.extraExtraLarge: 19,
UIContentSizeCategory.extraLarge: 17,
UIContentSizeCategory.large: 15,
UIContentSizeCategory.medium: 14,
UIContentSizeCategory.small: 13,
UIContentSizeCategory.extraSmall: 12
],
UIFontTextStyle.body: [
UIContentSizeCategory.accessibilityExtraExtraExtraLarge: 53,
UIContentSizeCategory.accessibilityExtraExtraLarge: 47,
UIContentSizeCategory.accessibilityExtraLarge: 40,
UIContentSizeCategory.accessibilityLarge: 33,
UIContentSizeCategory.accessibilityMedium: 28,
UIContentSizeCategory.extraExtraExtraLarge: 23,
UIContentSizeCategory.extraExtraLarge: 21,
UIContentSizeCategory.extraLarge: 19,
UIContentSizeCategory.large: 17,
UIContentSizeCategory.medium: 16,
UIContentSizeCategory.small: 15,
UIContentSizeCategory.extraSmall: 14
],
UIFontTextStyle.caption1: [
UIContentSizeCategory.accessibilityExtraExtraExtraLarge: 18,
UIContentSizeCategory.accessibilityExtraExtraLarge: 18,
UIContentSizeCategory.accessibilityExtraLarge: 18,
UIContentSizeCategory.accessibilityLarge: 18,
UIContentSizeCategory.accessibilityMedium: 18,
UIContentSizeCategory.extraExtraExtraLarge: 18,
UIContentSizeCategory.extraExtraLarge: 16,
UIContentSizeCategory.extraLarge: 14,
UIContentSizeCategory.large: 12,
UIContentSizeCategory.medium: 11,
UIContentSizeCategory.small: 11,
UIContentSizeCategory.extraSmall: 11
],
UIFontTextStyle.caption2: [
UIContentSizeCategory.accessibilityExtraExtraExtraLarge: 17,
UIContentSizeCategory.accessibilityExtraExtraLarge: 17,
UIContentSizeCategory.accessibilityExtraLarge: 17,
UIContentSizeCategory.accessibilityLarge: 17,
UIContentSizeCategory.accessibilityMedium: 17,
UIContentSizeCategory.extraExtraExtraLarge: 17,
UIContentSizeCategory.extraExtraLarge: 15,
UIContentSizeCategory.extraLarge: 13,
UIContentSizeCategory.large: 11,
UIContentSizeCategory.medium: 11,
UIContentSizeCategory.small: 11,
UIContentSizeCategory.extraSmall: 11
],
UIFontTextStyle.footnote: [
UIContentSizeCategory.accessibilityExtraExtraExtraLarge: 19,
UIContentSizeCategory.accessibilityExtraExtraLarge: 19,
UIContentSizeCategory.accessibilityExtraLarge: 19,
UIContentSizeCategory.accessibilityLarge: 19,
UIContentSizeCategory.accessibilityMedium: 19,
UIContentSizeCategory.extraExtraExtraLarge: 19,
UIContentSizeCategory.extraExtraLarge: 17,
UIContentSizeCategory.extraLarge: 15,
UIContentSizeCategory.large: 13,
UIContentSizeCategory.medium: 12,
UIContentSizeCategory.small: 12,
UIContentSizeCategory.extraSmall: 12
],
]
final class func preferredDescriptor(textStyle: String) -> UIFontDescriptor {
let contentSize = UIApplication.shared.preferredContentSizeCategory
let style = fontSizeTable[textStyle] as! NSDictionary
return UIFontDescriptor(name: SubStruct.preferredFontName, size: CGFloat((style[contentSize] as! NSNumber).floatValue))
}
}
并在viewDidLoad()
:
label.font = UIFont(descriptor: UIFontDescriptor.preferredDescriptor(textStyle: UIFontTextStyle.body.rawValue), size: 0)
NotificationCenter.default.addObserver(self, selector:#selector(self.userChangedTextSize(notification:)), name: NSNotification.Name.UIContentSizeCategoryDidChange, object: nil)
这是userChangedTextSize
功能:
func userChangedTextSize(notification: NSNotification) {
label.font = UIFont(descriptor: UIFontDescriptor.preferredDescriptor(textStyle: UIFontTextStyle.body.rawValue), size: 0)
}
这种方法的问题是文本大小在用户返回应用程序之前不会改变,然后用户会看到旧的文本大小变为新的大小,这并不理想。
我是否可以两全其美:自定义字体的大小会在后台自动更改?