When trying to remove the suffix from a filename, I'm only left with the suffix, which is exactly not what I want.
What (how many things) am I doing wrong here:
let myTextureAtlas = SKTextureAtlas(named: "demoArt")
let filename = (myTextureAtlas.textureNames.first?.characters.split{$0 == "."}.map(String.init)[1].replacingOccurrences(of: "\'", with: ""))! as String
print(filename)
This prints png which is the most dull part of the whole thing.
If by suffix you mean path extension, there is a method for this:
let filename = "demoArt.png"
let name = (filename as NSString).deletingPathExtension
// name - "demoArt"
Some people here seem to overlook that a filename can have multiple periods in the name and in that case only the last period separates the file extension. So this.is.a.valid.image.filename.jpg and stripping the extension should return this.is.a.valid.image.filename and not this (as two answers here would produce) or anything else in between. The regex answer works correctly but using a regex for that is a bit overkill (probably 10 times slower than using simple string processing). Here's a generic function that works for everyone:
func stripFileExtension ( _ filename: String ) -> String {
var components = filename.components(separatedBy: ".")
guard components.count > 1 else { return filename }
components.removeLast()
return components.joined(separator: ".")
}
print("1: \(stripFileExtension("foo"))")
print("2: \(stripFileExtension("foo.bar"))")
print("3: \(stripFileExtension("foo.bar.foobar"))")
Output:
foo
foo
foo.bar
You can also split the String using componentsSeparatedBy, like this:
let fileName = "demoArt.png"
var components = fileName.components(separatedBy: ".")
if components.count > 1 { // If there is a file extension
components.removeLast()
return components.joined(separator: ".")
} else {
return fileName
}
To clarify:
fileName.components(separatedBy: ".")
will return an array made up of "demoArt" and "png".
In iOS Array start with 0 and you want name of the file without extension, so you have split the string using ., now the name will store in first object and extension in the second one.
Simple Example
let fileName = "demoArt.png"
let name = fileName.characters.split(".").map(String.init).first
If you don't care what the extension is. This is a simple way.
let ss = filename.prefix(upTo: fileName.lastIndex { $0 == "." } ?? fileName.endIndex))
You may want to convert resulting substring to String after this. With String(ss)
#Confused with Swift 4 you can do this:
let fileName = "demoArt.png"
// or on your specific case:
// let fileName = myTextureAtlas.textureNames.first
let name = String(fileName.split(separator: ".").first!)
print(name)
Additionally you should also unwrapp first but I didn't want to complicate the sample code to solve your problem.
Btw, since I've also needed this recently, if you want to remove a specific suffix you know in advance, you can do something like this:
let fileName = "demoArt.png"
let fileNameExtension = ".png"
if fileName.hasSuffix(fileNameExtension) {
let name = fileName.prefix(fileName.count - fileNameExtension.count)
print(name)
}
How about using .dropLast(k) where k is the number of characters you drop from the suffix ?
Otherwise for removing extensions from path properly from filename, I insist you to use URL and .deletingPathExtension().lastPathComponent.
Maybe a bit overhead but at least it's a rock solid Apple API.
You can also use a Regexp to extract all the part before the last dot like that :
let fileName = "test.png"
let pattern = "^(.*)(\\.[a-zA-Z]+)$"
let regexp = try! NSRegularExpression(pattern: pattern, options: [])
let extractedName = regexp.stringByReplacingMatches(in: fileName, options: [], range: NSMakeRange(0, fileName.characters.count), withTemplate: "$1")
print(extractedName) //test
let mp3Files = ["alarm.mp3", "bubbles.mp3", "fanfare.mp3"]
let ringtonsArray = mp3Files.flatMap { $0.components(separatedBy: ".").first }
You can return a new string removing a definite number of characters from the end.
let fileName = "demoArt.png"
fileName.dropLast(4)
This code returns "demoArt"
One liner:
let stringWithSuffixDropped = fileName.split(separator: ".").dropLast().joined(separator: ".")
Related
I'm very, very new to Swift and admittedly struggling with some of its constructs. I have to work with a text file and do many manipulations - here's an example to illustrate the point:
let's say I have a text like this (multi line)
Mary had a little lamb
#name: a name
#summary: a paragraph of text
{{something}}
a whole bunch of multi-line text
x----------------x
I want to be able to do simple things like find the location of #name, then split it to get the name and so on. I've done this in javascript and it was pretty simple with the use of substr and the regex matches.
In swift, which is supposed to be swift and easy and what not, I'm finding this exceedingly confusing.
Can someone help with how one might do
Find the location of the start of a substring
Extract all text between from the end of a substring to the end of text
Sorry if this is trivial - but the Apple documentation feels very complicated, and lots of examples are years old. I can't also seem to find easy application of regex.
You can use string range(of: String) method to find the range of your string, get its upperBound and search for the end of the line from that position of the string:
Playground testing:
let sentence = """
Mary had a little lamb
#name: a name
#summary: a paragraph of text
{{something}}
a whole bunch of multi-line text
"""
if let start = sentence.range(of: "#name:")?.upperBound,
let end = sentence[start...].range(of: "\n")?.lowerBound {
let substring = sentence[start..<end]
print("name:", substring)
}
If you need to get the string from there to the end of the string you can use PartialRangeFrom:
if let start = sentence.range(of: "#summary:")?.upperBound {
let substring = sentence[start...]
print("summary:", substring)
}
If you find yourself using that a lot you can extend StringProtocol and create your own method:
extension StringProtocol {
func substring<S:StringProtocol,T:StringProtocol>(between start: S, and end: T, options: String.CompareOptions = []) -> SubSequence? {
guard
let lower = range(of: start, options: options)?.upperBound,
let upper = self[lower...].range(of: end, options: options)?.lowerBound
else { return nil }
return self[lower..<upper]
}
func substring<S:StringProtocol>(after string: S, options: String.CompareOptions = []) -> SubSequence? {
guard
let lower = range(of: string, options: options)?.upperBound else { return nil }
return self[lower...]
}
}
Usage:
let name = sentence.substring(between: "#name:", and: "\n") // " a name"
let sumary = sentence.substring(after: "#summary:") // " a paragraph of text\n\n{{something}}\n\na whole bunch of multi-line text"
You can use regular expressions as well:
let name = sentence.substring(between: "#\\w+:", and: "\\n", options: .regularExpression) // " a name"
You can do this with range() and distance():
let str = "Example string"
let range = str.range(of: "amp")!
print(str.distance(from: str.startIndex, to: range.lowerBound)) // 2
let lastStr = str[range.upperBound...]
print(lastStr) // "le string"
What's the best way to go about removing the first six characters of a string? Through Stack Overflow, I've found a couple of ways that were supposed to be solutions but I noticed an error with them. For instance,
extension String {
func removing(charactersOf string: String) -> String {
let characterSet = CharacterSet(charactersIn: string)
let components = self.components(separatedBy: characterSet)
return components.joined(separator: "")
}
If I type in a website like https://www.example.com, and store it as a variable named website, then type in the following
website.removing(charactersOf: "https://")
it removes the https:// portion but it also removes all h's, all t's, :'s, etc. from the text.
How can I just delete the first characters?
In Swift 4 it is really simple, just use dropFirst(n: Int)
let myString = "Hello World"
myString.dropFirst(6)
//World
In your case: website.dropFirst(6)
Why not :
let stripped = String(website.characters.dropFirst(6))
Seems more concise and straightforward to me.
(it won't work with multi-char emojis either mind you)
[EDIT] Swift 4 made this even shorter:
let stripped = String(website.dropFirst(6))
length is the number of characters you want to remove (6 in your case)
extension String {
func toLengthOf(length:Int) -> String {
if length <= 0 {
return self
} else if let to = self.index(self.startIndex, offsetBy: length, limitedBy: self.endIndex) {
return self.substring(from: to)
} else {
return ""
}
}
}
It will remove first 6 characters from a string
var str = "Hello-World"
let range1 = str.characters.index(str.startIndex, offsetBy: 6)..<str.endIndex
str = str[range1]
print("the end time is : \(str)")
I am looking for a way to search an Array of strings (containing filenames with extension) for dots (if the string contains characters-a dot-charaters, print the string definition). To do that I have to use something like wildcards (.).
So I tried this :
let testString = "*.*"
if Array[x].countains(testString)
{
print (Array[x])
}
or
if Array[x].range(of:testString) != nil
{
print (Array[x])
}
But it does not work. I guess I have to declare it differently but I don't know how and I have not found the right example.
Could someone shows some examples? Thank U.
Using this helper method on String:
extension String {
func contains(regex: NSRegularExpression) -> Bool {
let length = self.utf16.count // NSRanges are UTF-16 based!
let wholeString = NSRange(location: 0, length: length)
let matchCount = regex.numberOfMatches(in: self, range: wholeString)
return matchCount > 0
}
}
Then try this:
let fileNameWithExtension = try! NSRegularExpression(pattern: "\\w+[.]\\w+")
if Array[x].contains(regex: fileNameWithExtension) {
print(Array[x])
}
You may need to tweak my pattern above in order to match all cases you have in mind. This NSRegularExpression cheat sheet might help you there ;-)
I want to check whether my filename with just prefix is exist or not in Swift.
E.g
My file name is like Companies_12344
So after _ values are dynamic but "Companies_" is static.
How can i do that?
My code below For split
func splitFilename(str: String) -> (name: String, ext: String)? {
if let rDotIdx = find(reverse(str), "_")
{
let dotIdx = advance(str.endIndex, -rDotIdx)
let fname = str[str.startIndex..<advance(dotIdx, -1)]
println("splitFilename >> Split File Name >>\(fname)")
}
return nil
}
It's not very clear what you want to do, because your code snippet already does check if the string has the prefix.
There's a simpler way, though:
let fileName = "Companies_12344"
if fileName.hasPrefix("Companies") {
println("Yes, this one has 'Companies' as a prefix")
}
Swift's hasPrefix method checks if the string begins with the specified string.
Also, you could split the string easily with this:
let compos = fileName.componentsSeparatedByString("_") // ["Companies", "12344"]
Then you could check if there's a code and grab it with:
if let fileCode = compos.last {
println("There was a code after the prefix: \(fileCode)")
}
I'm having a problem with understand how I can work with substrings in Swift. Basically, I'm getting a JSON value that has a string with the following format:
Something
I'm trying to get rid of the HTML anchor tag with Swift so I'm left with Something. My thought was to find the index of every < and > in the string so then I could just do a substringWithRange and advance up to the right index.
My problem is that I can't figure out how to find the index. I've read that Swift doesn't support the index (unless you extend it.)
I don't want to add CPU cycles unnecessarily. So my question is, how do I find the indexes in a way that is not inefficient? Or, is there a better way of filtering out the tags?
Edit: Converted Andrew's first code sample to a function:
func formatTwitterSource(rawStr: String) -> String {
let unParsedString = rawStr
var midParseString = ""
var parsedString = ""
if let firstEndIndex = find(unParsedString, ">") {
midParseString = unParsedString[Range<String.Index>(start: firstEndIndex.successor(), end: unParsedString.endIndex)]
if let secondStartIndex = find(midParseString, "<") {
parsedString = midParseString[Range<String.Index>(start: midParseString.startIndex, end: secondStartIndex)]
}
}
return parsedString
}
Nothing too complicated. It takes in a String that has the tags in it. Then it uses Andrew's magic to parse everything out. I renamed the variables and made them clearer so you can see which variable does what in the process. Then in the end, it returns the parsed string.
You could do something like this, but it isn't pretty really. Obviously you would want to factor this into a function and possibly allow for various start/end tokens.
let testText = "Something"
if let firstEndIndex = find(testText, ">") {
let testText2 = testText[Range<String.Index>(start: firstEndIndex.successor(), end: testText.endIndex)]
if let secondStartIndex = find(testText2, "<") {
let testText3 = testText2[Range<String.Index>(start: testText2.startIndex, end: secondStartIndex)]
}
}
Edit
Working on this a little further and came up with something a little more idiomatic?
let startSplits = split(testText, { $0 == "<" })
let strippedValues = map(startSplits) { (s) -> String? in
if let endIndex = find(s, ">") {
return s[Range<String.Index>(start: endIndex.successor(), end: s.endIndex)]
}
return nil
}
let strings = map(filter(strippedValues, { $0 != "" })) { $0! }
It uses a little more functional style there at the end. Not sure I much enjoy the Swift style of map/filter compared to Haskell. But anyhow, the one potentially dangerous part is that forced unwrapping in the final map. If you can live with a result of [String?] then it isn't necessary.
Even though this question has been already answered, I am adding solution based on regex.
let pattern = "<.*>(.*)<.*>"
let src = "Something"
var error: NSError? = nil
var regex = NSRegularExpression(pattern: pattern, options: .DotMatchesLineSeparators, error: &error)
if let regex = regex {
var result = regex.stringByReplacingMatchesInString(src, options: nil, range: NSRange(location:0,
length:countElements(src)), withTemplate: "$1")
println(result)
}