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iOS 10.3: NSStrikethroughStyleAttributeName is not rendered if applied to a sub range of NSMutableAttributedString

A strikethrough (single, double, ...) added as attribute to an instance of NSMutableAttributedString is not rendered if the apply range is not the whole string range.

This happens using addAttribute(_ name: String, value: Any, range: NSRange), insert(_ attrString: NSAttributedString, at loc: Int), append(_ attrString: NSAttributedString), ...

Broken by Apple in early iOS 10.3 betas, and not fixed in 10.3 final.

Credit: https://openradar.appspot.com/31034683

Solution

  • Adding a NSBaselineOffsetAttributeName, as explained here, to the attributed string brings back the strikethrough line. Overriding drawText:in: can be slow especially on Collection View or Table View Cells.