NSTextContainer on Mac OS X has a method replaceLayoutManager: to replace the NSLayoutManager of NSTextView with a subclass of NSLayoutManager.
Unfortunately iOS doesn't have such a function.
I tried a combination of these lines of code, but it keeps crashing.
THLayoutManager *layoutManager = [[THLayoutManager alloc] init];
[layoutManager addTextContainer:[self textContainer]];
// [[self textStorage] removeLayoutManager:[self layoutManager]];
//[[self textStorage] addLayoutManager:layoutManager];
[[self textContainer] setLayoutManager:layoutManager];
What is the correct procedure to replace the NSLayoutManager of an UITextview?
Have a look at the WWDC2013 Intro To Text Kit video and sample code where they show how to do it.
https://developer.apple.com/downloads/index.action?name=WWDC%202013
https://developer.apple.com/wwdc/videos/
Below is an extract from the code
-(void)viewDidLoad
{
[super viewDidLoad];
// our auto layout views use a design spec that calls for
// 8 pts on each side except the bottom
// since we scroll at the top here, only inset the sides
CGRect newTextViewRect = CGRectInset(self.view.bounds, 8., 0.);
self.textStorage = [[TKDInteractiveTextColoringTextStorage alloc] init];
NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
NSTextContainer *container = [[NSTextContainer alloc] initWithSize:CGSizeMake(newTextViewRect.size.width, CGFLOAT_MAX)];
container.widthTracksTextView = YES;
[layoutManager addTextContainer:container];
[_textStorage addLayoutManager:layoutManager];
UITextView *newTextView = [[UITextView alloc] initWithFrame:newTextViewRect textContainer:container];
newTextView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
newTextView.scrollEnabled = YES;
newTextView.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;
[self.view addSubview:newTextView];
self.textView = newTextView;
self.textStorage.tokens = @{ @"Alice" : @{ NSForegroundColorAttributeName : [UIColor redColor] },
@"Rabbit" : @{ NSForegroundColorAttributeName : [UIColor orangeColor] },
TKDDefaultTokenName : @{ NSForegroundColorAttributeName : [UIColor blackColor] } };
}