How to encode the query part of the NSURL - ios

Question

(iOS 8.0+)
I want to use NSURL to pass some parameters in query part, like this:
NSURLComponents *components = [[NSURLComponents alloc] initWithString:#"ft://market/detail"];
NSDictionary *parameters = #{#"username" : #"高高高", #"from" : #"中国北京"};
NSMutableArray *items = [[NSMutableArray alloc] init];
for (NSString *key in parameters.allKeys) {
[items addObject:[[NSURLQueryItem alloc] initWithName:key value:parameters[key]]];
}
components.queryItems = items;
NSURL *url = components.URL;
NSLog(#"url : %#", url);
However, when I receive the URL and parse it, I find that the Chinese characters passed in the query part are abnormal, and I used NSURLComponents to parse the URL like this:
NSURLComponents *anaComponents = [NSURLComponents componentsWithString:url.absoluteString];
NSMutableDictionary *queryParams = [[NSMutableDictionary alloc] init];
for (NSURLQueryItem *querItem in anaComponents.queryItems) {
[queryParams setObject:querItem.value forKey:querItem.name];
}
NSLog(#"queryParams : %#", queryParams);
The following is the debug log:
url : ft://market/detail?username=%E9%AB%98%E9%AB%98%E9%AB%98&from=%E4%B8%AD%E5%9B%BD%E5%8C%97%E4%BA%AC
queryParams : {
from = "\U4e2d\U56fd\U5317\U4eac";
username = "\U9ad8\U9ad8\U9ad8";
}
The problem now seems to be that there is a problem with encoding and decoding of characters such as Chinese, even if [parameters[key] stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]] method is used to encode the query value, it is still wrong when decoding.
The query part I want to parse is like this : #{#"username" : #"高高高", #"from" : #"中国北京"};.
Hope for your helps here, Thanks sincerely.