How can i replace a specific word in a string in swift? - string

Question

I am looking for a way to replace a word inside a string in swift. Can anyone help?
this is what I have so far, I can find the specific word, but i do not know how to replace it...
var str = "helo, playgound"
var findWords = ["helo","playgound"]
var replaceWords = ["hello","playground"]
extension String {
var wordList:[String] {
return "".join(componentsSeparatedByCharactersInSet(NSCharacterSet.punctuationCharacterSet())).componentsSeparatedByString(" ")
}
}
func stringToArray() -> Array<String> {
var arr = str.wordList
return arr
}
func correction(var _arr:Array<String>) -> String{
for var i = 0; i < _arr.count; i++ {
if str.lowercaseString.rangeOfString(findWords[i]) != nil {
println("exists")
}
}
return str
}

Answer 1

It depends what your definition of a "word" is. If you're looking for an intelligent built-in notion of a "word", the easiest solution is probably to use NSRegularExpression, which knows where "word" boundaries are:
var s = NSMutableString(string:"hello world, go to hell")
let r = NSRegularExpression(
pattern: "\\bhell\\b",
options: .CaseInsensitive, error: nil)!
r.replaceMatchesInString(
s, options: nil, range: NSMakeRange(0,s.length),
withTemplate: "heaven")
After that, s is "hello world, go to heaven", which is the right answer; we replaced the "hell" that is a word, but not the "hell" in "hello". Notice that we are also matching case-insensitively, which seems to be one of your desiderata.
That example shows how do just one pair ("hell" and "heaven") but it is easy to abstract it into a method so that you can do it again and again for further pairs:
var str = "helo, playgound"
var findWords = ["helo", "playgound"]
var replaceWords = ["hello", "playground"]
func correct(str:String, orig:String, repl:String) -> String {
var s = NSMutableString(string:str)
let r = NSRegularExpression(
pattern: "\\b\(orig)\\b",
options: .CaseInsensitive, error: nil)!
r.replaceMatchesInString(
s, options: nil, range: NSMakeRange(0,s.length),
withTemplate: repl)
return s
}
for pair in Zip2(findWords,replaceWords) {
str = correct(str, pair.0, pair.1)
}
str // hello, playground

Answer 2

The easiest is probably this:
let statement = "Swift is hard."
let swiftRange = statement.startIndex..<advance(statement.startIndex, 5)
let newStatement = statement.stringByReplacingCharactersInRange(swiftRange, withString: "Objective-C")
// now newStatement = "Objective-C is hard."
Following a longer commenting tour: The above is under the assumption of the OP "I can find the specific word, but i do not know how to replace it...", so it's not about finding a "word" which to define is another discussion. It's just about replacing an already found word.
Another word on stringByReplacingCharactersInRange: #matt states that this is Cocoa cross-over. In that case Apple is telling a plain lie:
I fostered the web but there's no Apple source telling anything. Only the Foundation method for NSString. Their Swift book is silent too (in many respects). Well, I don't trust Apple anyway any longer since Yosemite-fail.