快速对单个UITextField进行多次验证

Question

I want multiple validation for VIN Number UITextField in Swift

• It should be Capital letters only

• It can contain 0-9 Numbers

• No spaces and special characters allowed

• Total length must be 16 characters

Answer 1

For Swift 3.0

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    if string.characters.count == 0 {
        return true
    }

    let currentText = textField.text ?? ""
    let prospectiveText = (currentText as NSString).replacingCharacters(in: range, with: string)

    return prospectiveText.containsOnlyCharactersIn(matchCharacters: "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ") &&
        prospectiveText.characters.count <= 16
}

extension String {

    func containsOnlyCharactersIn(matchCharacters: String) -> Bool {

        let disallowedCharacterSet = NSCharacterSet(charactersIn: matchCharacters).inverted
        return self.rangeOfCharacter(from: disallowedCharacterSet) == nil
    }
}

Answer 2

The best solution is regular expression! Simple as that [A-Z0-9]{16} .

NSString *testString=@"ABSDF9DFDSFPOIS1";
NSString *regExPattern = @"[A-Z0-9]{16}";

NSRegularExpression *regEx = [[NSRegularExpression alloc] initWithPattern:regExPattern options:NSRegularExpressionCaseInsensitive error:nil];
NSUInteger regExMatches = [regEx numberOfMatchesInString:testString options:0 range:NSMakeRange(0, [testString length])];

if (regExMatches==0) {
//Not matched
}

Take a look here to see how this regex works and you will realise how flexible is to change.

Answer 3

You can achieve all validation as following for Objective-C

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if(textField==YOUR_USER_NAME_TEXTFIELD || textField == YOUR_PASSWORD_TEXTFIELD)
    {

        NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"];
        for (int i = 0; i < [string length]; i++)
        {
            unichar c = [string characterAtIndex:i];
            if (![myCharSet characterIsMember:c])
            {
                return NO;
            }
        }

        return YES;
    }

    return YES;
}

for Total length must be 16 characters

You can count the length of yourtextfield.