drawTextInRect is super slow when use with foreign letters in iOS7

AliSoftware / OHAttributedLabel

UILabel that supports NSAttributedString

https://github.com/AliSoftware/OHAttributedLabel/wiki

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drawTextInRect is super slow when use with foreign letters in iOS7 #158

Closed kong707 closed 10 years ago

kong707 commented 10 years ago

This might due to bug from Apple. But I am not sure so I better ask it here.

My app scrolling performance is doing just fine in iOS6 . I have a label using OHAttributedLabel with dynamic height and content. But when I switch to iOS7 SDK. The scrolling performance drop drastically. I use profile tools and notice that the [OHAttributeLabel drawTextInRect] is expensive and causing the lag. This line of code is the problem

CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(cfAttrStrWithLinks);

But actually, if I try it with English content .Everything is fast. But with foreign text ,it turns out to be very slow. Any suggestions? I also tried to test with different font ( I set the custom uitableviewcell by interface builder) . But when it display the foreign text, it does not change at all.

AliSoftware commented 10 years ago

Unfortunately this is a problem with CTFramesetter and thus an issue with Apple CoreText.framework…

If you don't need the features other than displaying an NSAttributedString and you app support iOS6+ you may instead use UILabel as it supports NSAttributedString drawing with UIKit since iOS6.
If you need the specific features of OHAttributedLabel like adding custom links or keep support for iOS5, I encourage you to file an issue in bugreport.apple.com

kong707 commented 10 years ago

Thanks Ali, I still need to use OHAttributedLabel's features such as custom link for hashtag and url. So I am filing the bug to Apple right now.