I have seen questions in stackoverflow that convert unichar to NSString but now I would like to do the reverse.
How do i do it?
Need some guidance.. Thanks
For example, I have an array of strings:[#"o",#"p",#"q"];
These are strings inside. How do i convert it back to unichar?
The following will work as long as the first character isn't actually two composed characters (in other words as long as the character doesn't have a Unicode value greater than \UFFFF):
unichar ch = [someString characterAtIndex:0];
You could convert it to a buffer in NSData:
if ([string canBeConvertedToEncoding:NSUnicodeStringEncoding]) {
NSData * data = [string dataUsingEncoding:NSUnicodeStringEncoding];
const unichar* const ptr = (const unichar*)data.bytes;
...
}
Related
This question already has an answer here:
NSString containing hex convert to ascii equivalent
(1 answer)
Closed 6 years ago.
I have a Hex string like "000000000100" and I am using the following logic to do ASCII conversion, the output I am receiving is only 1 byte (\x01) But I want the output in the 6 byte format as \x00\x00\x00\x00\x01\x00
-(NSString*) decode
{
string=#"000000000100";
NSMutableString * newString = [[NSMutableString alloc]init];
int i = 0;
while (i < [string length])
{
NSString * hexChar = [string substringWithRange: NSMakeRange(i, 2)];
int value = 0;
sscanf([hexChar cStringUsingEncoding:NSASCIIStringEncoding], "%x", &value);
[newString appendFormat:#"%c", (char)value];
i+=2;
}
return newString;
}
How to do that ?
Let's first directly address your bug: In your code you attempt to add the next byte to your string with:
[newString appendFormat:#"%c", (char)value];
Your problem is that %c produces nothing if the character is a null, so you are appending an empty string and as you found end up with a string with a single byte in it.
You can fix your code by testing for the null and appending a string containing a single null:
if (value == 0)
[newString appendString:#"\0"]; // append a single null
else
[newString appendFormat:#"%c", (char)value];
Second, is this the way to do this?
Other answers have shown you other algorithms, they might be more efficient than yours as they only convert to a C-String once rather than repeatedly extract substrings and convert each one individually.
If and only if performance is a real issue for you you might wish to consider such C-based solutions. You clearly know how to use scanf, but in such a simple case as this you might want to look at digittoint and do the conversion of two hex digits to an integer yourself (value of first * 16 + value of second).
Conversely if you'd like to avoid C and scanf look at NSScanner and scanHexInt/scanHexLongLong - if your strings are never longer than 16 hex digits you can convert the whole string in one go and then produce an NSString from the bytes of the resultant unsigned 64-bit integer.
HTH
For example I could type an emoji character code such as:
NSString* str = #"π";
NSLog(#"%#", str);
The smile emoji would be seen in the console.
Maybe the code editor and the compiler would trade the literal in UTF-8.
And now I'm working in a full unicode, I mean 32bit per char, environment and I've got the unicode of the emoji, I want to convert the 32bit unicode into a NSString for example:
int charcode = 0x0001F60A;
NSLog(#"%??", charcode);
The question is what should I put at the "??" position and then I could format the charcode into a emoji string?
BTW the charcode was a variable which can not be determine at the compile time.
I don't want to compress the 32bit int into UTF-8 bytes unless that would be the only way.
If 0x0001F60A is a dynamic value determined at runtime then
you can use the NSString method
- (instancetype)initWithBytes:(const void *)bytes length:(NSUInteger)len encoding:(NSStringEncoding)encoding;
to create a string containing a character with the given Unicode value:
int charcode = 0x0001F60A;
uint32_t data = OSSwapHostToLittleInt32(charcode); // Convert to little-endian
NSString *str = [[NSString alloc] initWithBytes:&data length:4 encoding:NSUTF32LittleEndianStringEncoding];
NSLog(#"%#", str); // π
Use NSString initialization method
int charcode = 0x0001F60A;
NSLog(#"%#", [[NSString alloc] initWithBytes:&charcode length:4 encoding:NSUTF32LittleEndianStringEncoding]);
I have a unicode string as
{\rtf1\ansi\ansicpg1252\cocoartf1265
{\fonttbl\f0\fswiss\fcharset0 Helvetica;\f1\fnil\fcharset0 LucidaGrande;}
{\colortbl;\red255\green255\blue255;}
{\*\listtable{\list\listtemplateid1\listhybrid{\listlevel\levelnfc23\levelnfcn23\leveljc0\leveljcn0\levelfollow0\levelstartat1\levelspace360\levelindent0{\*\levelmarker \{check\}}{\leveltext\leveltemplateid1\'01\uc0\u10003 ;}{\levelnumbers;}\fi-360\li720\lin720 }{\listname ;}\listid1}}
{\*\listoverridetable{\listoverride\listid1\listoverridecount0\ls1}}
\paperw11900\paperh16840\margl1440\margr1440\vieww22880\viewh16200\viewkind0
\pard\li720\fi-720\pardirnatural
\ls1\ilvl0
\f0\fs24 \cf0 {\listtext
\f1 \uc0\u10003
\f0 }One\
{\listtext
\f1 \uc0\u10003
\f0 }Two\
}
Here i have unicode data \u10003 which is equivalent to "β" characters. I have used
[NSString stringWithCharacters:"\u10003" length:NSUTF16StringEncoding] which is throwing compilation error. Please let me know how to convert these unicode characters to "β".
Regards,
Boom
I have same for problem and the following code solve my issue
For Encode
NSData *dataenc = [yourtext dataUsingEncoding:NSNonLossyASCIIStringEncoding];
NSString *encodevalue = [[NSString alloc]initWithData:dataenc encoding:NSUTF8StringEncoding];
For decode
NSData *data = [yourtext dataUsingEncoding:NSUTF8StringEncoding];
NSString *decodevalue = [[NSString alloc] initWithData:data encoding:NSNonLossyASCIIStringEncoding];
Thanks
I have used below code to convert a Uniode string to NSString. This should work fine.
NSData *unicodedStringData =
[unicodedString dataUsingEncoding:NSUTF8StringEncoding];
NSString *emojiStringValue =
[[NSString alloc] initWithData:unicodedStringData encoding:NSNonLossyASCIIStringEncoding];
In Swift 4
let emoji = "π"
let unicodedData = emoji.data(using: String.Encoding.utf8, allowLossyConversion: true)
let emojiString = String(data: unicodedData!, encoding: String.Encoding.utf8)
I assume that:
You are reading this RTF data from a file or other external source.
You are parsing it yourself (not using, say, AppKit's built-in RTF parser).
You have a reason why you're parsing it yourself, and that reason isn't βwait, AppKit has this built in?β.
You have come upon \u⦠in the input you're parsing and need to convert that to a character for further handling and/or inclusion in the output text.
You have ruled out \uc, which is a different thing (it specifies the number of non-Unicode bytes that follow the \u⦠sequence, if I understood the RTF spec correctly).
\u is followed by hexadecimal digits. You need to parse those to a number; that number is the Unicode code point number for the character the sequence represents. You then need to create an NSString containing that character.
If you're using NSScanner to parse the input, then (assuming you have already scanned past the \u itself) you can simply ask the scanner to scanHexInt:. Pass a pointer to an unsigned int variable.
If you're not using NSScanner, do whatever makes sense for however you're parsing it. For example, if you've converted the RTF data to a C string and are reading through it yourself, you'll want to use strtoul to parse the hex number. It'll interpret the number in whatever base you specify (in this case, 16) and then put the pointer to the next character wherever you want it.
Your unsigned int or unsigned long variable will then contain the Unicode code point value for the specified character. In the example from your question, that will be 0x10003, or U+10003.
Now, for most characters, you could simply assign that over to a unichar variable and create an NSString from that. That won't work here: unichars only go up to 0xFFFF, and this code point is higher than that (in technical terms, it's outside the Basic Multilingual Plane).
Fortunately, *CF*String has a function to help you:
unsigned int codePoint = /*β¦*/;
unichar characters[2];
NSUInteger numCharacters = 0;
if (CFStringGetSurrogatePairForLongCharacter(codePoint, characters)) {
numCharacters = 2;
} else {
characters[0] = codePoint;
numCharacters = 1;
}
You can then use stringWithCharacters:length: to create an NSString from this array of 16-bit characters.
Use this:
NSString *myUnicodeString = #"\u10003";
Thanks to modern Objective C.
Let me know if its not what you want.
NSString *strUnicodeString = "\u2714";
NSData *unicodedStringData = [strUnicodeString dataUsingEncoding:NSUTF8StringEncoding];
NSString *emojiStringValue = [[NSString alloc] initWithData:unicodedStringData encoding:NSUTF8StringEncoding];
I am allowing the user to input some data into the TextField. The user inputs Ε 1234D into the TextField.
The code I have looks like this:
NSString *string = textField.text;
for (int nCtr = 0; nCtr < [string length]; nCtr++) {
const char chars = [string characterAtIndex:nCtr];
int isAlpha = isalpha(chars);
}
string output looks like this:Ε 1234D
Then I printed the first chars value, it looks like this:'`' instead of 'Ε '. Why is this so? I would like to allow special characters in my code as well.
Any suggestion would be welcome as well. Need some guidance. Thanks
You are truncating the character value as [NSString chatacterAtIndex:] returns unichar (16-bit) and not char (8-bit). try:
unichar chars = [string characterAtIndex:nCtr];
UPDATE: Also note that you shouldn't be using isalpha() to test for letters, as that is restricted to Latin character sets and you need something that can cope with non-latin characters. Use this code instead:
NSCharacterSet *letterSet = [NSCharacterSet letterCharacterSet];
NSString *string = textField.text;
for (NSUIntger nCtr = 0; nCtr < [string length]; nCtr++)
{
const unichar c = [string characterAtIndex:nCtr];
BOOL isAlpha = [letterSet characterIsMember:c];
...
}
characterAtIndex: returns a unichar (2-byte Unicode character), not char (1-byte ASCII character). By casting it to char, you are getting only one of the two bytes.
You should turn on your compiler warnings. I believe "Suspicious implicit conversions" should do the trick.
On a separate note, you can't use isAlpha(char) with a unichar. Use [[NSCharacterSet letterCharacterSet] characterIsMember:chars]
I am trying to create an NSString object from a const unichar buffer where I don't know the length of the buffer.
I want to use the NSString stringWithCharacters: length: method to create the string (this seems to work), but please can you help me find out the length?
I have:
const unichar *c_emAdd = [... returns successfully from a C++ function...]
NSString *emAdd = [NSString stringWithCharacters:c_emAdd length = unicharLen];
Can anyone help me find out how to check what unicharLen is? I don't get this length passed back to me by the call to the C++ function, so I presume I'd need to iterate until I find a terminating character? Anyone have a code snippet to help? Thanks!
Is your char buffer null terminated?
Is it 16-bit unicode?
NSString *emAdd = [NSString stringWithFormat:#"%S", c_emAdd];
Your unichars should be null terminated so you when you reach two null bytes (a unichar = 0x0000) in the pointer you will know the length.
unsigned long long unistrlen(unichar *chars)
{
unsigned long long length = 0llu;
if(NULL == chars) return length;
while(NULL != chars[length])
length++;
return length;
}
//...
//Inside Some method or function
unichar chars[] = { 0x005A, 0x0065, 0x0062, 0x0072, 0x0061, 0x0000 };
NSString *string = [NSString stringWithCharacters:chars length:unistrlen(chars)];
NSLog(#"%#", string);
Or even simpler format with %S specifier