iOS-银行卡输入\输出格式化显示

项目中要实现:

• 银行卡的输入, 一般要求实现 输入每4位分隔;
• tableViewCell中显示银行卡数字一般以**** **** **** **** 879格式显示

以下是总结的代码

1.输入

#pragma mark - UITextFieldDelegate
// 银行卡输入每4位分隔
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    if (textField == _cardNumberTF) {
            // 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 >= 20) {
                return NO;  
            }
            [textField setText:newString];
            return NO;
        }
        return YES;
    }

2.显示

// 给定字符串根据指定的个数进行分组，每一组用空格分隔
- (NSString *)groupedString:(NSString *)string {

    NSString *str = [string stringByReplacingOccurrencesOfString:@" " withString:@"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, string.length)];

    // 根据长度计算分组的个数
    NSInteger groupCount = (NSInteger)ceilf((CGFloat)str.length /4);
    NSMutableArray *components = [[NSMutableArray alloc] init];

    for (NSInteger i = 0; i < groupCount; i++) {
        if (i*4 + 4 > str.length) {
            [components addObject:[str substringFromIndex:i*4]];
        } else {
            NSString * secureStr = [str substringWithRange:NSMakeRange(i*4, 4)];
            secureStr = [secureStr stringByReplacingCharactersInRange:NSMakeRange(0, 4) withString:@"****"];
            [components addObject:secureStr];
        }
    }
    NSString *groupedString = [components componentsJoinedByString:@" "];
    return groupedString;
}