Question

我有一个像@＆＃34; 1234123412341234＆＃34;这样的字符串，我需要在每4个字符之间追加空格。

@"1234 1234 1234 1234"

即我需要NSString类似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);
}

Answer 1

以下是NSString

上的类别的unicode感知实现

@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

尝试使用此测试字符串：

NSString *string = @"ab  132487 387  e e e ";
NSLog(@"%@", [string stringByFormattingAsCreditCardNumber]);

该方法适用于非BMP字符（即表情符号）并处理现有的空格。

Answer 2

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;
}

<强>更新

您的代码将在第一个插入空间字符：

这是您的originalString：

Text:     123412341234
Location: 012345678901

根据您的代码，在第一个插入空格字符时，您将插入＆＃34; 1＆＃34; （位置为4 ）

之后，你的字符串是：

Text:     1234 12341234
Location: 0123456789012

所以，你看，现在你必须在 9 （9％4 ！= 0）的位置插入第二个空间字符

希望您自己修复代码！

Answer 3

您的代码非常接近，但该方法的更好的语义是为任何给定的输入字符串返回新的NSString：

-(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 4

here的代码段可以做你想做的事情：

- (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

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
}

Answer 6

请确保您的字符串长度应为4。
该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;
}

NSString每4个字符附加一次WhiteSpace

6 个答案: