Kerning in iOS UITextView
You are right that your app would probably be rejected by using @selector(setContentToHTMLString:). You can however use a simple trick to construct the selector dynamically so that it will not be detected during validation.
NSString *css = @"*{text-rendering: optimizeLegibility;}";NSString *html = [NSString stringWithFormat:@"<html><head><style>%@</style></head><body>Your HTML Text</body></html>", css];@try { SEL setContentToHTMLString = NSSelectorFromString([@[@"set", @"Content", @"To", @"HTML", @"String", @":"] componentsJoinedByString:@""]); #pragma clang diagnostic push #pragma clang diagnostic ignored "-Warc-performSelector-leaks" [textView performSelector:setContentToHTMLString withObject:html]; #pragma clang diagnostic pop}@catch (NSException *exception) { // html+css could not be applied to text view, so no kerning}By wrapping the call inside a @try/@catch block, you also ensure that your app will not crash if the setContentToHTMLString: method is removed in a future version of iOS.
Using private APIs is generally not recommended, but in this case I think it totally makes sense to use a small hack vs rewriting UITextView with CoreText.
After researching this a bit I found that the reason for the missing Kerning is that UITextView internally uses a UIWebDocumentView which has Kerning turned off by default.
Some infos about the inner workings of UITextView: http://www.cocoanetics.com/2012/12/uitextview-caught-with-trousers-down/
Unfortunately there is no sanctioned method to enable Kerning, I would definitely advise against using a hack using a camouflaged selector.
Here's my Radar, I suggest you dupe it: http://www.cocoanetics.com/2012/12/radar-uitextview-ignores-font-kerning/
In this I argue that when setting text on UITextView via setAttributedText we developers expect for Kerning to be on by default because that is how it would most closely match output of rendering the text via CoreText.
Try this:
[textView_ setValue:@"hello, <b>world</b>" forKey:@"contentToHTMLString"];It works in my test. I haven't tried it in the app store of course.