I have used this line of code before release of iOS 10.3 ,and worked fine.
NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] in
As mentioned above, this is an iOS 10.3 bug.
We needed an immediate workaround, so just in case anyone is looking for hints:
Our Label had attributes set through both NSMutableAttributedString
as well as NSMutableParagraphStyle
. The bug did not occur when using no / an "empty" paragraph style (instance without any properties set).
So in this scenario, omitting the paragraph style and working around the then missing paragraph properties resolved the issue for us.