VoiceOver reads attributed strings in multiple segments on iOS 15

[NickEntin]

VoiceOver now appears to read attributed strings in segments based on attribute ranges. You can see this behavior through the following example:

let attributedText = NSMutableAttributedString(string: "Hello world")
attributedText.addAttributes([.kern: 1], range: NSRange(location: 9, length: 1))

let label = UILabel()
label.attributedText = attributedText

VoiceOver will read this as Hello wor, l, d. This reproduces for a variety of attributes such as kerning, foreground color, and background color.

I was able to reproduce this on iOS 15.1.1, but not on iOS 13.3. As far as I know this is a new issue on iOS 15, but it's possible it applies to 14 as well.

[NickEntin]

We have also reproduced this in iOS 15.0.

[NickEntin]

And this does not reproduce on iOS 14, so confirmed this is a behavior change in iOS 15.

[NickEntin]

Did a more thorough test on iOS 15.3.1 and found the following.

These attributes trigger this behavior:

• .backgroundColor
• .ligature
• .kern
• .tracking
• .strikethroughStyle
• .underlineStyle
• .strokeColor
• .strokeWidth
• .attachment
• .link
• .underlineColor
• .strikethroughColor
• .obliqueness
• .expansion
• .writingDirection
• .verticalGlyphForm

These attributes do not trigger the behavior:

• .foregroundColor
• .font
• .paragraphStyle
• .shadow
• .textEffect
• .baselineOffset

I'm not sure why some attributes do and some don't, and I had tested .foregroundColor before with a different result, so I'm not sure if that changed across minor OS versions.