Syntax-highlighting Text With a Custom List of Keywords - ios

Question

I'm working on a macOS application. I need to syntax-highlight text that is placed over TextView (NSTextView) with a list of selected words. For simplicity, I'm actually testing the same feature on the iPhone Simulator. Anyway, a list of words to highlight comes as a form of an array. The following is what I have.
func HighlightText {
let tagArray = ["let","var","case"]
let style = NSParagraphStyle.defaultParagraphStyle().mutableCopy() as! NSMutableParagraphStyle
style.alignment = NSTextAlignment.Left
let words = textView.string!.componentsSeparatedByString(" ") // textView.text (UITextView) or textView.string (NSTextView)
let attStr = NSMutableAttributedString()
for i in 0..<words.count {
let word = words[i]
if HasElements.containsElements(tagArray,text: word,ignore: true) {
let attr = [
NSForegroundColorAttributeName: syntaxcolor,
NSParagraphStyleAttributeName: style,
]
let str = (i != words.count-1) ? NSAttributedString(string: word.stringByAppendingString(" "), attributes: attr) : NSAttributedString(string: word, attributes: attr)
attStr.appendAttributedString(str)
} else {
let attr = [
NSForegroundColorAttributeName: NSColor.blackColor(),
NSParagraphStyleAttributeName: style,
]
let str = (i != words.count-1) ? NSAttributedString(string: word.stringByAppendingString(" "), attributes: attr) : NSAttributedString(string: word, attributes: attr)
attStr.appendAttributedString(str)
}
}
textView.textStorage?.setAttributedString(attStr)
}
class HasElements {
static func containsElements(array:Array<String>,text:String,ignore:Bool) -> Bool {
var has = false
for str in array {
if str == text {
has = true
}
}
return has
}
}
The simple methodology here is to separate the entire string of text into words with a white space (" ") and puts each word in an array (words). The containsElements function simply tells whether or not the selected word contains one of the keywords in the array (tagArray). If it returns true, the word is put in an NSMutableAttributedString with a highlight color. Otherwise, it's put in the same attributed string with a plain color.
The problem with this simple methodology is that a separated word puts the last word and /n and the next word together. For example, if I have a string like
let base = 3
let power = 10
var answer = 1
, only the first 'let' will be highlighted as the code puts 3 and the next let together like '3\nlet.' If I separate any word containing \n with a fast enumeration, the code won't detect each new paragraph well. I appreciate any advice to make it better. Just FYI, I'm going to leave this topic open to both macOS and iOS.
Muchos thankos

Answer 1

Couple different options. String has a function called componentsSeparatedByCharactersInSet that allows you to separate by a character set you define. Unfortunately this won't work since you want to separate by \n which is more than one character.
You could split the words twice.
let firstSplit = textView.text!.componentsSeparatedByString(" ")
var words = [String]()
for word in firstSplit {
let secondSplit = word.componentsSeparatedByString("\n")
words.appendContentsOf(secondSplit)
}
But then you wouldn't have any sense of the line breaks.. You'd need to re add them back in.
Finally, the easiest hack is simply:
let newString = textView.text!.stringByReplacingOccurrencesOfString("\n", withString: "\n ")
let words = newString.componentsSeparatedByString(" ")
So basically you add your own spaces.