How to replace a substring in a string in Swift

Question

my code is like the following:

let fileName = "/users/lezi/downloads/Zootopia.srt"
var srtFile = try? String(contentsOfFile: fileName)
let range = srtFile?.range(of: "00:00:59,825")
print(srtFile?[range!])
srtFile?.replaceSubrange(range!, with: "00:00:59,826")
print(srtFile?[range!])

I hope the "00:00:59,825" is replaced to "00:00:59,826", but the print is "Optional("\r\n\r\n2")\n", some characters just before "00:00:59,825"

What language is the srt file for, maybe this is caused by some encoding issue? — Joakim Danielson, Jun 22 '20 at 12:21
I can reproduce this with a Chinese srt file, then I also get some garbage in the second `print`. Using `replacingoccurenzces(of:with)` seems to work though so it seems that this should be closed as a duplicate — Joakim Danielson, Jun 22 '20 at 12:34
@JoakimDanielson: Using `range(of:)` and `replaceSubrange()` should work as well (and is *not* equivalent to `replacingOccurrences(of:with:)`). I think it would be more helpful to figure out why the above code does not work as expected (instead of closing as a duplicate of a question about a different method). — Martin R, Jun 22 '20 at 12:40
@MartinR You are right. The `replaceSubrange` function works fine, it is the second `print(srtFile?[range])` statement that doesn't work. If I print the whole file I can see the change. So I guess this then should be closed as "Can not reproduce"? — Joakim Danielson, Jun 22 '20 at 12:49
srtFile?.replacingOccurrences(of: "00:00:55,775", with: "00:00:59,826") this code replace nothing,while the following coe works, let range = srtFile?.range(of: "00:00:55,775") print(srtFile?[range!]) srtFile?.replaceSubrange(range!, with: "00:00:59,826") — 龙方哲, Jun 22 '20 at 12:52
if I change the substring to "00:00:59,825", both don't work — 龙方哲, Jun 22 '20 at 12:55
Note that `replacingOccurrences` returns an updated string. The original string stays unchanged, unless you do `srtFile = srtFile.replacingOccurrences(...)` — koen, Jun 22 '20 at 13:07

score 3 · Accepted Answer · answered Jun 22 '20 at 12:06

3

You can try using replacingOccurrences(of:with:). Returns a new string in which all occurrences of a target string in the receiver are replaced by another given string

sample example :

let str = "Swift 4.0 is the best version of Swift to learn, so if you're starting fresh you should definitely learn Swift 4.0."
let replaced = str.replacingOccurrences(of: "4.0", with: "5.0")

answered Jun 22 '20 at 12:06

Kevin Siundu

46
5

1

Thank you, but if that's the answer, the question is then a duplicate of https://stackoverflow.com/questions/24200888/any-way-to-replace-characters-on-swift-string – Cœur Jun 22 '20 at 12:29
replacingOccurrences and replaceSubrange both works, but the range got before replaceSubrange seems invalid after replaceSubrange is executed – 龙方哲 Jun 24 '20 at 03:11

score 1 · Answer 2 · answered Jun 22 '20 at 12:08

1

Regardless of use case. The common syntax to replace the substring is:

str.replacingOccurrences(of: "replace_this", with: "with_this")

where replace_thisis the text string you want to replace and ```with_this`` is the new sub-string to insert.

answered Jun 22 '20 at 12:08

Sudip Ghimire

677
6
15

1

Thank you, but if that's the answer, the question is then a duplicate of https://stackoverflow.com/questions/24200888/any-way-to-replace-characters-on-swift-string – Cœur Jun 22 '20 at 12:29
Yes. It is a method of String.NSString not a method of String. Makes it hard to find! – Worik Nov 27 '22 at 21:25

How to replace a substring in a string in Swift

2 Answers2