NSString append WhiteSpace for every 4 Character - ios

Question

I have a string like #"1234123412341234", i need to append space between every 4 chars like.
#"1234 1234 1234 1234"
i.e, I need a NSString like Visa Card Type. I have tried like this but i didn't get my result.
-(void)resetCardNumberAsVisa:(NSString*)aNumber
{
NSMutableString *s = [aNumber mutableCopy];
for(int p=0; p<[s length]; p++)
{
if(p%4==0)
{
[s insertString:#" " atIndex:p];
}
}
NSLog(#"%#",s);
}

Answer 1

Here's a unicode aware implementation as a category on NSString:
#interface NSString (NRStringFormatting)
- (NSString *)stringByFormattingAsCreditCardNumber;
#end
#implementation NSString (NRStringFormatting)
- (NSString *)stringByFormattingAsCreditCardNumber
{
NSMutableString *result = [NSMutableString string];
__block NSInteger count = -1;
[self enumerateSubstringsInRange:(NSRange){0, [self length]}
options:NSStringEnumerationByComposedCharacterSequences
usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
if ([substring rangeOfCharacterFromSet:[NSCharacterSet whitespaceCharacterSet]].location != NSNotFound)
return;
count += 1;
if (count == 4) {
[result appendString:#" "];
count = 0;
}
[result appendString:substring];
}];
return result;
}
#end
Try it with this test string:
NSString *string = #"ab 😗😌 132487 387 e e e ";
NSLog(#"%#", [string stringByFormattingAsCreditCardNumber]);
The method works with non-BMP characters (i.e. emoji) and handles existing white space.

Answer 2

Your code is pretty close, however a better semantic for the method is to return a new NSString for any given input string:
-(NSString *)formatStringAsVisa:(NSString*)aNumber
{
NSMutableString *newStr = [NSMutableString new];
for (NSUInteger i = 0; i < [aNumber length]; i++)
{
if (i > 0 && i % 4 == 0)
[newStr appendString:#" "];
unichar c = [aNumber characterAtIndex:i];
[newStr appendString:[[NSString alloc] initWithCharacters:&c length:1]];
}
return newStr;
}

Answer 3

You should do like this:
- (NSString *)resetCardNumberAsVisa:(NSString*)originalString {
NSMutableString *resultString = [NSMutableString string];
for(int i = 0; i<[originalString length]/4; i++)
{
NSUInteger fromIndex = i * 4;
NSUInteger len = [originalString length] - fromIndex;
if (len > 4) {
len = 4;
}
[resultString appendFormat:#"%# ",[originalString substringWithRange:NSMakeRange(fromIndex, len)]];
}
return resultString;
}
UPDATE:
You code will be right on the first inserting space charactor:
This is your originalString:
Text: 123412341234
Location: 012345678901
Base on your code, on the first you insert space character, you will insert at "1" (with location is 4)
And after that, your string is:
Text: 1234 12341234
Location: 0123456789012
So, you see it, now you have to insert second space charater at location is 9 (9%4 != 0)
Hope you can fix your code by yourself!

Answer 4

The code snippet from here do what do you want:
- (NSString *)insertSpacesEveryFourDigitsIntoString:(NSString *)string
andPreserveCursorPosition:(NSUInteger *)cursorPosition
{
NSMutableString *stringWithAddedSpaces = [NSMutableString new];
NSUInteger cursorPositionInSpacelessString = *cursorPosition;
for (NSUInteger i=0; i<[string length]; i++) {
if ((i>0) && ((i % 4) == 0)) {
[stringWithAddedSpaces appendString:#" "];
if (i < cursorPositionInSpacelessString) {
(*cursorPosition)++;
}
}
unichar characterToAdd = [string characterAtIndex:i];
NSString *stringToAdd =
[NSString stringWithCharacters:&characterToAdd length:1];
[stringWithAddedSpaces appendString:stringToAdd];
}
return stringWithAddedSpaces;
}

Answer 5

swift3 based on Droppy
func codeFormat(_ code: String) -> String {
let newStr = NSMutableString()
for i in 0..<code.characters.count {
if (i > 0 && i % 4 == 0){
newStr.append(" ")
}
var c = (code as NSString).character(at: i)
newStr.append(NSString(characters: &c, length: 1) as String)
}
return newStr as String
}

Answer 6

Please make sure that your string length should times by 4.
This solution will insert on the right hand side first.
- (NSString*) fillWhiteGapWithString:(NSString*)source
{
NSInteger dl = 4;
NSMutableString* result = [NSMutableString stringWithString:source];
for(NSInteger cnt = result.length - dl ; cnt > 0 ; cnt -= dl)
{
[result insertString:#" " atIndex:cnt];
}
return result;
}