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My Swift app involves searching through text in a UITextView. The user can search for a certain substring within that text view, then jump to any instance of that string in the text view (say, the third instance). I need to find out the integer value of which character they are on.
For example:
Example 1: The user searches for "hello" and the text view reads "hey hi hello, hey hi hello", then the user presses down arrow to view second instance. I need to know the integer value of the first h in the second hello (i.e. which # character that h in hello is within the text view). The integer value should be 22.
Example 2: The user searches for "abc" while the text view reads "abcd" and they are looking for the first instance of abc, so the integer value should be 1 (which is the integer value of that a since it's the first character of the instance they're searching for).
How can I get the index of the character the user is searching for?
777
To access certain parts of a string or to modify it, Swift provides the Swift. Index type which represents the position of each Character in a String. The above prefix(upTo:) method returns a Substring and not a String.
To find substring of a String in Swift, prepare Range object using start and end indices, then give this Range object to the string in square brackets as an index.
The swift string class does not provide the ability to get a character at a specific index because of its native support for UTF characters. The variable length of a UTF character in memory makes jumping directly to a character impossible. That means you have to manually loop over the string each time.
Xcode 11 • Swift 5 or later
let sentence = "hey hi hello, hey hi hello"
let query = "hello"
var searchRange = sentence.startIndex..<sentence.endIndex
var indices: [String.Index] = []
while let range = sentence.range(of: query, options: .caseInsensitive, range: searchRange) {
searchRange = range.upperBound..<searchRange.upperBound
indices.append(range.lowerBound)
}
print(indices) // "[7, 21]\n"
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