I want to append a unichar to NSMutableString. I have
var outputString: NSMutableString = "Some string"
let letterA: unichar = 0x1820
I saw the question Appending unichar to NSMutableString. The accepted answer (in Objective C) says:
[s appendFormat:#"%C", c];
but I can't figure out the Swift syntax. The documentation doesn't help much, either.
I even tried
outputString += letterA
but that also didn't work.
Note: I'm not trying to append a Swift String or append a Swift Character.
Use the same method appendFormat in swift like this
Rewriting your code to elaborate
var outputString: NSMutableString = "Some string"
let letterA: unichar = 0x1820
outputString.appendFormat("%C", letterA)
outputString.appendFormat("%C", letterA) appends the character in Swift 1.2 running in Xcode 6.4. It appears to be the same method you've referenced in the Objective-C sample.
NSMutableString
The NSMutableString reference does not need to be a var
let outputString:NSMutableString = "Some string"
outputString.appendFormat("%C", 0x0041) // Letter A
Native Swift String
Solution skipping NSFoundation and unichar classes:
var outputString = "Some string"
outputString += "\u{41}" // Letter A is actually 0x0041
Related
Input:
chris#mydomain.com
steve#mydomain.com
Output:
chris
steve
I'm looking to get the substring before the # character. In Python, I would use something like: myString = myString[:myString.find("#")] but I think Swift's version is very complex, at least from what I've been reading. Would it be better to bridge to Obj-C in this case, since Swift's indexOf/find function looks something like this mess: Finding index of character in Swift String ?
Something like this, even though it's using arrays, seems to be the simpliest route:
contact = contact.componentsSeparatedByString("#")[0]
In Swift, Python myString[:myString.find("#")] is equivalent to:
myString[myString.startIndex ..< find(myString, "#")!]
But this causes a runtime error unless myString contains "#".
This is safer.
if let found = find(myString, "#") {
myString = myString[myString.startIndex ..< found]
}
Note that, find() searches Character only, not substring. so you cannot:
find(myString, "#mydomain")
This may help you
let arr = split(contact, { $0 == "#"}, maxSplit: Int.max, allowEmptySlices: false)
println(arr[0])
I believe you have hit the nail on the head. Another option is to use regular expressions to find it. I'm still learning swift, but the objective-c version of things is as follows:
-(NSString*) parseEmailPrefix(NSString*)email{
NSError *error = nil;
NSString *pattern = #"([A-Z0-9a-z._%+-]+)#[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
NSRegularExpression *expression = [NSRegularExpression regularExpressionWithPattern:pattern
options:0
error:&error];
NSTextCheckingResult *result = [expression firstMatchInString:email
options:0
range:NSMakeRange(0, email.length)];
return [string substringWithRange:[result rangeAtIndex:1]];
}
This is in my opinion harder to read, but it has the added benefit of validating the email as you go.
Regex credit: Regex for email address
And then there is this Obj-C snippet, which addresses more specifically the data given in the question. (Forgive that I have not translated to Swift, still working on that skill.)
NSString* email = #"chuck#norris.net";
NSURL* theURL = [NSURL URLWithString:[NSString stringWithFormat:#"mailto://%#", email]];
NSLog(#"%# at %#", theURL.user, theURL.host); // yields "chuck at norris.net"
This works:
var str: String = "Hello#World"
let a = str.componentsSeparatedByString("#")
println("\(a[0])")
Output is "Hello"
I am making an nsmutable array by separating a string by component it is causing a lot of new line and white spaces to be inserted in the array how to identify and remove them?
for (int i=0;i<contentsOfFile.count; i++)
{
if(!([[contentsOfFile objectAtIndex:i]isEqual:#"\n"]||[[contentsOfFile objectAtIndex:i]isEqual:#""]))
[arrayToBereturned addObject:[contentsOfFile objectAtIndex:i]];
}
this code which i am using cannot identify all new line charectors
thanks
To remove all extra space and \n from your string-
NSString* result = [yourString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
than prepare your contentsOfFile Array.
If you want an array without whitespace:
NSString *string = #"Hello, World!";
NSCharacterSet *separator = [NSCharacterSet whitespaceAndNewlineCharacterSet];
NSArray *stringComponents = [string componentsSeparatedByCharactersInSet:separator];
stringByTrimmingCharachersInSet: only removes desired characters from the end and the beginning of the string. To remove all occurences you should use stringByReplacingOccurrencesOfString:
Swift 5 version
let string = "Hello, stack overflow!"
let components = string.components(separatedBy: .whitespacesAndNewlines)
print(components) // prints ["Hello,", "stack", "overflow!"]
Also regarding string.replacingOccurrences
let string = " Hello, stack overflow ! "
let noSpacingsString = string.replacingOccurrences(of: " ", with: "")
print(components) // prints "Hello,stackoverflow!"
I'm developing an iPhone app. In a label, I want to show an user's first letter of the name uppercase. How do I do that?
If there is only one word String, then use the method
-capitalized
let capitalizedString = myStr.capitalized // capitalizes every word
Otherwise, for multi word strings, you have to extract first character and make only that character upper case.
(2014-07-24: Currently accepted answer is not correct) The question is very specific: Make the first letter uppercase, leave the rest lowercase. Using capitalizedString produces a different result: “Capitalized String” instead of “Capitalized string”. There is another variant depending on the locale, which is capitalizedStringWithLocale, but it's not correct for spanish, right now it's using the same rules as in english, so this is how I'm doing it for spanish:
NSString *abc = #"this is test";
abc = [NSString stringWithFormat:#"%#%#",[[abc substringToIndex:1] uppercaseString],[abc substringFromIndex:1] ];
NSLog(#"abc = %#",abc);
In case someone is still interested in 2016, here is a Swift 3 extension:
extension String {
func capitalizedFirst() -> String {
let first = self[self.startIndex ..< self.index(startIndex, offsetBy: 1)]
let rest = self[self.index(startIndex, offsetBy: 1) ..< self.endIndex]
return first.uppercased() + rest.lowercased()
}
func capitalizedFirst(with: Locale?) -> String {
let first = self[self.startIndex ..< self.index(startIndex, offsetBy: 1)]
let rest = self[self.index(startIndex, offsetBy: 1) ..< self.endIndex]
return first.uppercased(with: with) + rest.lowercased(with: with)
}
}
Then you use it exactly as you would for the usual uppercased() or capitalized():
myString.capitalizedFirst() or myString.capitalizedFirst(with: Locale.current)
Simply
- (NSString *)capitalizeFirstLetterOnlyOfString:(NSString *)string{
NSMutableString *result = [string lowercaseString].mutableCopy;
[result replaceCharactersInRange:NSMakeRange(0, 1) withString:[[result substringToIndex:1] capitalizedString]];
return result;
}
This is for your NSString+Util category...
- (NSString *) capitalizedFirstLetter {
NSString *retVal;
if (self.length < 2) {
retVal = self.capitalizedString;
} else {
retVal = string(#"%#%#",[[self substringToIndex:1] uppercaseString],[self substringFromIndex:1]);
}
return retVal;
}
You can do that with NSString stringWithFormat, of course. I use this weirdness:
#define string(...) \
[NSString stringWithFormat:__VA_ARGS__]
As an extension to the accepted answer
capitalizedString is used for making uppercase letters .
NSString *capitalizedString = [myStr capitalizedString]; // capitalizes every word
But if you have many words in a string and wants to get only first character as upper case use the below solution
NSString *firstCapitalChar = [[string substringToIndex:1] capitalizedString];
NSString *capString = [string stringByReplacingCharactersInRange:NSMakeRange(0,1) withString: capString];
// extract first character and make only that character upper case.
here's a swift extension for it
extension NSString {
func capitalizeFirstLetter() -> NSString {
return self.length > 1 ?
self.substringToIndex(1).capitalizedString + self.substringFromIndex(1) :
self.capitalizedString
}
}
This is how it worked for me:
NSString *serverString = jsonObject[#"info"];
NSMutableString *textToDisplay = [NSMutableString stringWithFormat:#"%#", serverString];
[textToDisplay replaceCharactersInRange:NSMakeRange(0, 1) withString:[textToDisplay substringToIndex:1].capitalizedString];
cell.infoLabel.text = textToDisplay;
Hope it helps.
Swift:
let userName = "hard CODE"
yourLabel.text = userName.localizedUppercaseString
I recommend using this localised version of uppercase, since names are locale sensitive.
I'm looking for a way to make sure a string can be used as a file name under iOS. I'm currently in the section of the code that deletes incompatible characters. I'm wondering if I'm doing it right.
NSString *filename = #"A file name";
fileName = [fileName stringByTrimmingCharactersInSet: [NSCharacterSet controlCharacterSet]];
fileName = [fileName stringByTrimmingCharactersInSet: [NSCharacterSet newlineCharacterSet]];
I'm also wondering if there's already a method that validates a string as a file name.
Thank you for your advice!
Use RegEx:
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"[^a-zA-Z0-9_]+" options:0 error:nil];
filename = [regex stringByReplacingMatchesInString:filename options:0 range:NSMakeRange(0, filename.length) withTemplate:#"-"];
I find this to be cleaner and probably much more performant. This is based on Angel Naydenov's solution, but first constructing Character set with all invalid characters and then calling components(separatedBy:) just once.
Swift 3 & 4
var invalidCharacters = CharacterSet(charactersIn: ":/")
invalidCharacters.formUnion(.newlines)
invalidCharacters.formUnion(.illegalCharacters)
invalidCharacters.formUnion(.controlCharacters)
let newFilename = originalFilename
.components(separatedBy: invalidCharacters)
.joined(separator: "")
Swift 2
let invalidCharacters = NSMutableCharacterSet(charactersInString: ":/")
invalidCharacters.formUnionWithCharacterSet(NSCharacterSet.newlineCharacterSet())
invalidCharacters.formUnionWithCharacterSet(NSCharacterSet.illegalCharacterSet())
invalidCharacters.formUnionWithCharacterSet(NSCharacterSet.controlCharacterSet())
let filename = originalFilename
.componentsSeparatedByCharactersInSet(invalidCharacters)
.joinWithSeparator("")
First of all, you're using the wrong method. Trimming the string will only remove characters in the beginning and the end of the string.
What you're looking for is something more like:
fileName = [fileName stringByReplacingOccurrencesOfString:#"/" withString:#"_"];
However, that's a suboptimal solution, since you'll have to do that for every character you want to exclude, so maybe you want to keep looking or write you're own method for manipulating the string.
iOS is UNIX based and as such I suppose it supports almost any characters in filenames. UNIX allows white spaces, <, >, |, \, :, (, ), &, ;, as well as wildcards such as ? and *, to be quoted or escaped using \ symbol. However I wouldn't use any of those characters in my filenames. In fact, I would restrict the characters in my filenames to 'a'-'z', '0'-'9', '_' and '.'.
As I did not see a list with allowed characters in this question but the question wanted a list with such characters I am adding a bit more details on this topic.
First we need to know what is the file system that iOS devices use. Using multiple online sources this seems to be HFSX which is the HFS+ case sensitive version. And including one link here for reference: https://apple.stackexchange.com/questions/83671/what-filesystem-does-ios-use
Now that we know what the file system is we can look for what characters are not allowed. And these seem to be: colon (:) and slash (/). Here is a link for reference: http://www.comentum.com/File-Systems-HFS-FAT-UFS.html
Having this information and what others have written in this thread my personal preference for removing not allowed characters from file names is the following Swift code:
filename = "-".join(filename.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet()))
filename = "-".join(filename.componentsSeparatedByCharactersInSet(NSCharacterSet.illegalCharacterSet()))
filename = "-".join(filename.componentsSeparatedByCharactersInSet(NSCharacterSet.controlCharacterSet()))
filename = "-".join(filename.componentsSeparatedByString(":"))
filename = "-".join(filename.componentsSeparatedByString("/"))
The reason I am not preferring the RegEx approach is that it seems too restrictive to me. I do not want to restrict my users only to Latin characters. They may as well wish to use some Chinese, Cyrillic or whatever else they like.
Happy coding!
I've had to save remote files locally with filenames containing other characters than basic alpha-numeric characters. I use the method below to strip out potential invalid characters, ensuring it's a valid filename for the filesystem when generating a NSURL using URLWithString:
filename = [[filename componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:#"" ];
filename = [[filename componentsSeparatedByCharactersInSet:[NSCharacterSet illegalCharacterSet]] componentsJoinedByString:#"" ];
filename = [[filename componentsSeparatedByCharactersInSet:[NSCharacterSet symbolCharacterSet]] componentsJoinedByString:#"" ];
fileURLString = [NSTemporaryDirectory() stringByAppendingPathComponent:filename];
fileURL = [NSURL URLWithString:fileURLString];
You may also want to test for collision errors first using:
[[NSFileManager defaultManager] fileExistsAtPath:[fileURL absoluteString]]
This String extension (Swift 4.2) will help convert an invalid iOS file name to a valid iOS file name.
extension String {
func convertToValidFileName() -> String {
let invalidFileNameCharactersRegex = "[^a-zA-Z0-9_]+"
let fullRange = startIndex..<endIndex
let validName = replacingOccurrences(of: invalidFileNameCharactersRegex,
with: "-",
options: .regularExpression,
range: fullRange)
return validName
}
}
For example
"name.name?/!!23$$#1asd".convertToValudFileName() // "name-name-23-1asd"
"!Hello.312,^%-0//\r\r".convertToValidFileName() // "-Hello-312-0-"
"/foo/bar/pop?soda=yes|please".convertToValidFileName() // "-foo-bar-pop-soda-yes-please"
I'm pretty happy with this solution:
NSString *testString = #"This*is::/legal.😀,?縦書き 123";
NSString *result = [[[testString componentsSeparatedByCharactersInSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet]] filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"length > 0"]] componentsJoinedByString:#"-"];
Output:
"This-is-legal-縦書き-123"
What is this sorcery?
Let me break it up into multiple lines so it's clear what's going on:
NSString *testString = #"This*is::/legal.😀,?縦書き 123";
// Get a character set for everything that's NOT alphanumeric.
NSCharacterSet *nonAlphanumericCharacterSet = [[NSCharacterSet alphanumericCharacterSet] invertedSet];
// Split the string on each non-alphanumeric character, thus removing them.
NSArray *cleanedUpComponentsWithBlanks = [testString componentsSeparatedByCharactersInSet:nonAlphanumericCharacterSet];
// Filter out empty strings ("length" is a KVO-compliant property that the predicate can call on each NSString in the array).
NSArray *cleanedUpComponentsWithoutBlanks = [cleanedUpComponentsWithBlanks filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"length > 0"]];
// Put the components back together and join them with a "-".
NSString *result = [cleanedUpComponentsWithoutBlanks componentsJoinedByString:#"-"];
Enjoy!
Swift 4 Version
Added by john-pang on 2021-09-01 with Swift version:
let testString = "This*is::/legal.😀,?縦書き 123"
// Get a character set for everything that's NOT alphanumeric.
let nonAlphanumericCharacterSet = CharacterSet.alphanumerics.inverted
// Split the string on each non-alphanumeric character, thus removing them.
let cleanedUpComponentsWithBlanks = testString.components(separatedBy: nonAlphanumericCharacterSet)
// Filter out empty strings ("length" is a KVO-compliant property that the predicate can call on each NSString in the array).
let cleanedUpComponentsWithoutBlanks = cleanedUpComponentsWithBlanks.filter { $0.length > 0 }
// Put the components back together and join them with a "-".
let result = cleanedUpComponentsWithoutBlanks.joined(separator: "_")
I came up with the following solution. Works nice so far.
import Foundation
extension String {
func removeUnsupportedCharactersForFileName() -> String {
var cleanString = self
["?", "/", "\\", "*"].forEach {
cleanString = cleanString.replacingOccurrences(of: $0, with: "-")
}
return cleanString
}
}
let a = "***???foo.png"
let validString = a.removeUnsupportedCharactersForFileName()
Base on Marian Answers, here is a string extension to remove any unwanted characters.
extension String {
func stripCharacters() -> String {
var invalidCharacters = CharacterSet(charactersIn: ":/")
invalidCharacters.formUnion(.newlines)
invalidCharacters.formUnion(.illegalCharacters)
invalidCharacters.formUnion(.controlCharacters)
let newString = self
.components(separatedBy: invalidCharacters)
.joined(separator: "_")
return newString
}
}
Example:
let fileName = "Man(lop23/45"
let newFileName = fileName.stripCharacters()
print(newFileName)
Swift 5 extension:
I wanted to remove emojis as well and in windows \ is also an invalid character. So I added symbols charset and backslash \ as well.
extension String {
var validFilename: String {
let invalidCharsets = CharacterSet(charactersIn: ":/\\")
.union(.illegalCharacters)
.union(.controlCharacters)
.union(.symbols)
.union(.newlines)
return self.components(separatedBy: invalidCharsets).joined()
}
}
In Objective-C for iOS, how would I remove the last character of a string using a button action?
In your controller class, create an action method you will hook the button up to in Interface Builder. Inside that method you can trim your string like this:
if ([string length] > 0) {
string = [string substringToIndex:[string length] - 1];
} else {
//no characters to delete... attempting to do so will result in a crash
}
If you want a fancy way of doing this in just one line of code you could write it as:
string = [string substringToIndex:string.length-(string.length>0)];
*Explanation of fancy one-line code snippet:
If there is a character to delete (i.e. the length of the string is greater than 0)
(string.length>0) returns 1 thus making the code return:
string = [string substringToIndex:string.length-1];
If there is NOT a character to delete (i.e. the length of the string is NOT greater than 0)
(string.length>0) returns 0 thus making the code return:
string = [string substringToIndex:string.length-0];
Which prevents crashes.
If it's an NSMutableString (which I would recommend since you're changing it dynamically), you can use:
[myString deleteCharactersInRange:NSMakeRange([myRequestString length]-1, 1)];
The solutions given here actually do not take into account multi-byte Unicode characters ("composed characters"), and could result in invalid Unicode strings.
In fact, the iOS header file which contains the declaration of substringToIndex contains the following comment:
Hint: Use with rangeOfComposedCharacterSequencesForRange: to avoid breaking up composed characters
See how to use rangeOfComposedCharacterSequenceAtIndex: to delete the last character correctly.
The documentation is your friend, NSString supports a call substringWithRange that can shorten the string that you have an return the shortened String. You cannot modify an instance of NSString it is immutable. If you have an NSMutableString is has a method called deleteCharactersInRange that can modify the string in place
...
NSRange r;
r.location = 0;
r.size = [mutable length]-1;
NSString* shorted = [stringValue substringWithRange:r];
...