Why does the computation time for boundingRect of NSAttributedString become significantly longer in iOS15.2?
This is the result measured with the iPhone simulator. (700 lines of Hiragana)
・iPhone13Pro, iOS15.0 : 0.012s
・iPhone13Pro, iOS15.2 : 2.318s
The sample code has been uploaded to github.
Compare iOS 15.2 with iOS 15.1 or lower versions. https://github.com/kimuyonsoku/BoundingRectTest
Is this on a background thread or a main thread.
Could you test on device ?
It is running in MainThread.
https://github.com/kimuyonsoku/BoundingRectTest/blob/main/BoundingRectTest/ViewController.swift
I didn't measure the exact time, but on device, iPhone6s (iOS14.7.1) was very fast and iPhone11Pro (iOS15.2.1) was very slow.
A bug report has been filed [FB9855886]
Thanks.
Looking at your bug it seem likely that this is caused by a string bridging problem. The -boundingRectWithSize:options:attributes:context: method you’re calling is implementing in Objective-C, so it works best when the String value is an NSString under the covers. Something in the OS has caused your string to be converted to a Swift string, which results in a lot of bridging overhead within -boundingRectWithSize:options:attributes:context:.
It’s possible that you could work around this issue by tweaking your code to ensure that your String is actually an NSString. I don’t have a specific recommendation for how to do that. Creating that would take time, more time than I have to spend here on DevForums. You should play around with this concept yourself to see if you can make any headway. If not, I recommend that you to open a DTS tech support incident so that I, or one of my colleagues, can look into this in detail (make sure to reference this DevForums thread).
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