Crash when request params values are other than NSString

[pszalko]

NSString (NXOAuth2) category crashes when parameter value is other than NSString.

The following code requires every param value to be NSString, but it doesn't check if it's true.

+ (NSString *)nxoauth2_stringWithEncodedQueryParameters:(NSDictionary *)parameters;
{

    NSMutableArray *parameterPairs = [NSMutableArray array];
    for (NSString *key in [parameters allKeys]) {
        NSString *pair = [NSString stringWithFormat:@"%@=%@", [key nxoauth2_URLEncodedString], [[parameters objectForKey:key] nxoauth2_URLEncodedString]];
        [parameterPairs addObject:pair];
    }
    return [parameterPairs componentsJoinedByString:@"&"];
}

Steps to reproduce the issue is to pass anything than NSString to as parameters value.

Example dictionary:

parameters = @{@"key" : @34}