简书

输入银行卡号要自限制？我有好方法！

校验银行卡号？我有好方法！

构建思路

1. 选择合适的键盘
2. 输入时进行调整
3. 结束编辑再次调整

核心规避风险

贴代码演示
class:superclass<UIUITextFieldDelegate>

self.CardNoField.text = [[UITextField alloc]init];

self.CardNoField.delegate = self;

• 键盘设置建议使用的键盘UIKeyboardTypeNumberPad

图片发自简书App

    self.CardNoField.keyboardType = UIKeyboardTypeNumberPad;

代理中应做的:

• 编辑时

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    
    NSLog(@"%@",string);
    
    if ([string isEqualToString:@" "]) {
        return NO;
    }
    if(self.CardNoField == textField){
        if ([string isEqualToString:@"."]&&newLength == 18) {
            textField.text = [NSString stringWithFormat:@"%@X",textField.text];
            return NO;
        }if ([string isEqualToString:@"."]) {
            return NO;
        }
        
        NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789"] invertedSet];
        NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
        return [string isEqualToString:filtered]&&newLength <= 19? YES :NO   ;
    }
    return newLength <= 16;
    
}

• 结束编辑再次调整

- (void)textFieldDidEndEditing:(UITextField *)textField;{
    if (self.CardNoField== textField) {
        NSCharacterSet *setToRemove = [[ NSCharacterSet characterSetWithCharactersInString:@"0123456789"]
                                       invertedSet ];
        textField.text  = [[textField.text  componentsSeparatedByCharactersInSet:setToRemove] componentsJoinedByString:@""];
    }
}

• 校验是否正确

+ (BOOL) checkCardNo:(NSString*) cardNo{
    if (cardNo.length<15) {
        return NO;
    }
    int oddsum = 0;     //奇数求和
    int evensum = 0;    //偶数求和
    int allsum = 0;
    int cardNoLength = (int)[cardNo length];
    int lastNum = [[cardNo substringFromIndex:cardNoLength-1] intValue];
    
    cardNo = [cardNo substringToIndex:cardNoLength - 1];
    for (int i = cardNoLength -1 ; i>=1;i--) {
        NSString *tmpString = [cardNo substringWithRange:NSMakeRange(i-1, 1)];
        int tmpVal = [tmpString intValue];
        if (cardNoLength % 2 ==1 ) {
            if((i % 2) == 0){
                tmpVal *= 2;
                if(tmpVal>=10)
                    tmpVal -= 9;
                evensum += tmpVal;
            }else{
                oddsum += tmpVal;
            }
        }else{
            if((i % 2) == 1){
                tmpVal *= 2;
                if(tmpVal>=10)
                    tmpVal -= 9;
                evensum += tmpVal;
            }else{
                oddsum += tmpVal;
            }
        }
    }
    
    allsum = oddsum + evensum;
    allsum += lastNum;
    if((allsum % 10) == 0)
        return YES;
    else
        return NO;
}

谢谢！

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