登录字符串校验

//去除textfield.text字符串中前后字符串

NSString *pwdStr =  [_pwdTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

//字符串替换

NSString *search = @"_";

NSString *replace= @"-";

NSRange substr = [trainNumber rangeOfString:search];

while (substr.location!=NSNotFound) {

[trainNumber replaceCharactersInRange:substr withString:replace];

substr = [trainNumber rangeOfString:search];

}

//字符串中小写字母，转换成大写字母

for (int i=0; i<trainNumber.length; i++) {
        NSRange range = NSMakeRange(i, 1);
        NSString *subString = [trainNumber substringWithRange:range];
        const char *cString = [subString UTF8String];
        if (strlen(cString)==1) {
            NSString *changeUper = [subString uppercaseString];
            [trainNumber replaceCharactersInRange:range withString:changeUper];
        }
    }