Exceeding max Text("") concatenation length - SwiftUI - - ios

Question

With reference to the answer posted by Asperi (https://stackoverflow.com/users/12299030/asperi) on Question: Highlight a specific part of the text in SwiftUI
I have found his answer quite useful, however, when my String input exceeds 32k characters the app crashes, so I am assuming the String() is a max of 32k and am looking for a work around.
In my app, if someone searches for the word "pancake", the search word will be stored and when the user looks at the detail page (of lets say a recipe), the word pancake will highlight. All works well with this answer, but when the recipe exceeds 32k characters, the app crashes with exceeding index range messages. (specific error message: Thread 1: EXC_BAD_ACCESS (code=2, address=0x16d43ffb4))
Here is the modified code from the answer on that question:
This will print the data:
hilightedText(str: self.recipes.last!.recipeData!)
.multilineTextAlignment(.leading)
.font(.system(size: CGFloat( settings.fontSize )))
There is obviously more to this code above, but in essence, it iterates a database, and finds the last record containing 'search word' and displays the recipeData here, which is a large string contained in the database.
to implement the highlightedText functionality:
func hilightedText(str: String) -> Text {
let textToSearch = searched
var result: Text!
for word in str.split(separator: " ") {
var text = Text(word)
if word.uppercased().contains(textToSearch.uppercased()) {
text = text.bold().foregroundColor(.yellow)
}
//THIS NEXT LINE has been identified as the problem:
result = (result == nil ? text : result + Text(" ") + text)
}
return result
}
I've modified the answer from Asperi slightly to suit my needs and all works really well, unless I come across a recipeData entry that is larger than 32k in size, as stated before.
I have tried Replacing String with a few other data types and nothing works..
Any ideas?
Thank you!
UPDATE:
After lengthy discussion in the comments, it appears that the root cause of the issue is at some point, for some records, I am exceeding the maximum Text("") concatenations.
In the above code, each word is split out, evaluated and added to the long string "result" which winds up looking like this:
Text("word") + Text(" ") + Text("Word")
and so on.
This is done, so I can easily apply color attributes per word, but it would seem that once I hit a certain number of words (which is less that 32k, one record was 22k and crashed), the app crashes.
Leo suggested https://stackoverflow.com/a/59531265/2303865 this thread as an alternative and I will have to attempt to implement that instead.
Thank you..

Answer 1

Hmm... unexpected limitation... anyway - learn something new.
Ok, here is improved algorithm, which should move that limitation far away.
Tested with Xcode 12 / iOS 14. (also updated code in referenced topic Highlight a specific part of the text in SwiftUI)
func hilightedText(str: String, searched: String) -> Text {
guard !str.isEmpty && !searched.isEmpty else { return Text(str) }
var result = Text("")
var range = str.startIndex..<str.endIndex
repeat {
guard let found = str.range(of: searched, options: .caseInsensitive, range: range, locale: nil) else {
result = result + Text(str[range])
break
}
let prefix = str[range.lowerBound..<found.lowerBound]
result = result + Text(prefix) + Text(str[found]).bold().foregroundColor(.yellow)
range = found.upperBound..<str.endIndex
} while (true)
return result
}

Answer 2

After much discussion in the comments, it became clear that I was hitting a maximum Text() concatenations limit, so beware, apparently there is one.
I realized however that I only needed to have a split Text("Word") when that particular word required special formatting (IE highlighting, etc), otherwise, I could concat all of the raw strings together and send that as a Text("String of words").
This approach mitigated the action of having every single word sent as a Text("Word" by itself and cut down greatly on the number of Text()'s being returned.
see code below that solved the issue:
func hilightedText(str: String) -> Text {
let textToSearch = searched
var result = Text(" ")
var words: String = " "
var foundWord = false
for line in str.split(whereSeparator: \.isNewline) {
for word in line.split(whereSeparator: \.isWhitespace) {
if word.localizedStandardContains(textToSearch) {
foundWord = true
result += Text(words) + Text(" ") + Text(word).bold().foregroundColor(.yellow)
} else {
if foundWord {
words = ""
}
foundWord = false
words += " " + word
}
}
words += "\n\n"
}
return result + Text(" ") + Text(words)
}
extension Text {
static func += (lhs: inout Text, rhs: Text) {
lhs = lhs + rhs
}
}
It could use some cleanup as also discussed in the comments for splitting by whitespace, etc, but this was just to overcome the issue of crashing. Needs some additional testing before I call it good, but no more crashing..
ADDED:
the suggestion to use separator by .isWhiteSpace worked, but when I put it back together, everything was a space, no more line breaks, so I added the extra split by line breaks to preserve the line breaks.