子串在NSString中带有星号

Question

嗨朋友,我想在表视图单元格中显示信用卡号,所以我想只显示最后四个字符,如XXXXXXXXXX1111第一个字符替换为x或其他字符我怎么能这样做可以任何一个帮助我,
我试过像波纹管

NSString *CardNumber = [CardNumberValues objectAtIndex:indexPath.row];
NSRange subStringRange = NSMakeRange(0,[CardNumber length]-4); 
NSMutableCharacterSet *NumSet = [NSMutableCharacterSet characterSetWithRange:subStringRange];
CardNumber = [[CardNumber componentsSeparatedByCharactersInSet:NumSet] componentsJoinedByString:@"X"];
cell.CardNumber.text = CardNumber;

但它不起作用你可以建议任何参考或代码......

Answer 1

用这个

NSString *CardNumber = @"12345678901234";
NSString *str_padding=@"";
    NSRange subStringRange = NSMakeRange(0,[CardNumber length]-4); 
    str_padding =[str_padding stringByPaddingToLength:subStringRange.length withString:@"X" startingAtIndex:0];
    CardNumber = [CardNumber stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"%@",[CardNumber substringToIndex:subStringRange.length]] withString:str_padding];
    NSLog(@"%@",CardNumber);