iOS 输入银行卡号每4位一起展示

1.输入银行卡号

UITableView 有一个cell需要输入银行卡号，每输入4位后面加一个空格

//银行卡每4位展示
- (BOOL)textField:(ML_BaseTextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    
    if (textField.indexPath.section == 1 && textField.indexPath.row == 2) {
        // 4位分隔银行卡卡号
        NSString *text = [textField text];
        
        NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
        string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
        if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
            return NO;
        }
        
        text = [text stringByReplacingCharactersInRange:range withString:string];
        text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
        
        NSString *newString = @"";
        while (text.length > 0) {
            NSString *subString = [text substringToIndex:MIN(text.length, 4)];
            newString = [newString stringByAppendingString:subString];
            if (subString.length == 4) {
                newString = [newString stringByAppendingString:@" "];
            }
            text = [text substringFromIndex:MIN(text.length, 4)];
        }
        
        newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];
        
        if ([newString stringByReplacingOccurrencesOfString:@" " withString:@""].length >= 21) {
            return NO;
        }
        [textField setText:newString];
        return NO;
    }
    return YES;
}

2.显示银行卡号

没有空格的银行卡号，没4位间隔的显示出来

//银行卡每四位显示
- (NSString *)formatterBankCardNum:(NSString *)string{
    if (![string notNilOrEmpty]) {
        return nil;
    }
    NSString *tempStr=string;
    NSInteger size =(tempStr.length / 4);
    NSMutableArray *tmpStrArr = [[NSMutableArray alloc] init];
    
    for (int n = 0;n < size; n++){
        [tmpStrArr addObject:[tempStr substringWithRange:NSMakeRange(n*4, 4)]];
    }
    [tmpStrArr addObject:[tempStr substringWithRange:NSMakeRange(size*4, (tempStr.length % 4))]];
    tempStr = [tmpStrArr componentsJoinedByString:@" "];
    return tempStr;
}