xcode NSString 为每 4 个字符附加空格

NSString append WhiteSpace for every 4 Character

提问by Harish

I have a string like @"1234123412341234", i need to append space between every 4 chars like.

我有一个像@"1234123412341234"这样的字符串，我需要在每 4 个字符之间添加空格。

@"1234 1234 1234 1234"

i.e, I need a NSStringlike Visa Card Type. I have tried like this but i didn't get my result.

即，我需要一个NSString类似的 Visa 卡类型。我试过这样，但我没有得到我的结果。

-(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);
}

回答by Nikolai Ruhe

Here's a unicode aware implementation as a category on NSString:

这是一个 unicode 感知实现作为一个类别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:

用这个测试字符串试试：

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.

该方法适用于非 BMP 字符（即表情符号）并处理现有的空白。

回答by Tony

You should do like this:

你应该这样做：

- (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:

更新：

You code will be right on the first inserting space charactor:

您的代码将在第一个插入空格字符上：

This is your originalString:

这是你的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)

根据您的代码，在您第一次插入空格字符时，您将插入“1”（位置为 4）

And after that, your string is:

在那之后，你的字符串是：

Text:     1234 12341234
Location: 0123456789012

So, you see it, now you have to insert second space charater at location is 9(9%4 !=0)

所以，你看它，现在你必须在位置9(9%4 !=0)插入第二个空格字符

Hope you can fix your code by yourself!

希望你能自己修复你的代码！

回答by Droppy

Your code is pretty close, however a better semantic for the method is to return a new NSStringfor any given input string:

您的代码非常接近，但是该方法更好的语义是NSString为任何给定的输入字符串返回一个新的：

-(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;
}

回答by Szu

The code snippet from heredo what do you want:

从代码段在这里做你想做的事：

- (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;
}

回答by zander zhang

swift3 based on Droppy

基于 Droppy 的 swift3

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
}

回答by Wanpaya

Please make sure that your string length should times by 4.
This solution will insert on the right hand side first.

请确保您的字符串长度应乘以 4。
此解决方案将首先插入右侧。

- (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;
}