How do I find the existing UIFontTextStyle of a UILabel?

Question

I'm currently creating an extension on UILabel to facilitate observing dynamic type. Once a UIContentSizeCategoryDidChangeNotification is received, I'd like my selector to set the label's font by using

self.font = UIFont.preferredFontForTextStyle(someUIFontTextStyle)

where someUIFontTextStyle uses the same UIFontTextStyle the label currently exhibits. I had hoped such a property would be accessible via something like self.font.fontDescriptor.textStyle, but the truth seems a bit more convoluted.

Is there a way to access the UIFontTextStyle property associated with a UILabel?

Solution

self.font.fontDescriptor().objectForKey(UIFontDescriptorTextStyleAttribute) as? String

score 4 · Answer 1 · edited May 23 '17 at 10:30

4

As you discovered and Andy mentioned, you can get the font's text style from its font descriptor:

self.font.fontDescriptor().objectForKey(UIFontDescriptorTextStyleAttribute) as? String

edited May 23 '17 at 10:30

Community

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answered Aug 31 '15 at 23:54

Thanks so much! Your solution does precisely what I needed. Alternatively, I found accessing `myLabel.font.fontDescriptor().objectForKey(UIFontDescriptorTextStyleAttribute) as? String` will yield the same success without using a non-public key. – lauragone Sep 02 '15 at 15:56
`UIFontDescriptorTextStyleAttribute` is the correct key. – pronebird Oct 17 '15 at 18:52
@Andy Thanks. I've updated the answer and credited you. – Oct 17 '15 at 19:48

score 3 · Accepted Answer · answered Dec 21 '16 at 05:18

The accepted answer is not quite right for swift 3. The handler for UIContentSizeCategoryDidChangeNotification needs to do the following:

if let font = myUILable.font.fontDescriptor.object(forKey: UIFontDescriptorTextStyleAttribute) as? UIFontTextStyle {
    myUILabel.font = UIFont.preferredFont(forTextStyle: font)
}

How do I find the existing UIFontTextStyle of a UILabel?

Solution

2 Answers2