Formatting a UITextField for credit card input like (xxxx xxxx xxxx xxxx)

Question

I want to format a UITextField for entering a credit card number into such that it only allows digits to be entered and automatically inserts spaces so that the

Answer 1

Define below method & call it in UITextfield delegates or wherever required

-(NSString*)processString :(NSString*)yourString
{
    if(yourString == nil){
        return @"";
    }
    int stringLength = (int)[yourString length];
    int len = 4;  // Length after which you need to place added character
    NSMutableString *str = [NSMutableString string];
    int i = 0;
    for (; i < stringLength; i+=len) {
        NSRange range = NSMakeRange(i, len);
        [str appendString:[yourString substringWithRange:range]];
        if(i!=stringLength -4){
            [str appendString:@" "]; //If required string format is XXXX-XXXX-XXXX-XXX then just replace [str appendString:@"-"]
        }
    }
    if (i < [str length]-1) {  // add remaining part
        [str appendString:[yourString substringFromIndex:i]];
    }
    //Returning required string

    return str;
}