#Encoding and Decoding URL Data
To percent-encode part of a URL string, use the ==NSString== method ==stringByAddingPercentEncodingWithAllowedCharacters==:, passing the appropriate character set for the URL component or subcomponent: • User: ==URLUserAllowedCharacterSet== • Password: ==URLPasswordAllowedCharacterSet== • Host: ==URLHostAllowedCharacterSet== • Path: ==URLPathAllowedCharacterSet== • Fragment: ==URLFragmentAllowedCharacterSet== • Query: ==URLQueryAllowedCharacterSet==
Important: Don’t use stringByAddingPercentEncodingWithAllowedCharacters: to encode an entire URL string, because each URL component or subcomponent has different rules for what characters are valid.
For example, to percent-encode a UTF-8 string for inclusion in a URL path, you do the following:
NSString *str = @"http://192.168.2.123:80/u=142020185,2790987080&fm=26&gp=0的副本.jpg";
NSString *urlStr = [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
[str stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLPathAllowedCharacterSet]];
NSURL *url = [NSURL URLWithString:urlStr];
If you want to decode a percent-encoded URL component, use NSURLComponents to split the URL into its constituent parts and access the corresponding property. For example, to get the UTF-8 string value for a percent-encoded URL path, you do the following:
NSString *encodeStr = @"http://192.168.2.123:80/u=142020185,2790987080&fm=26&gp=0%E7%9A%84%E5%89%AF%E6%9C%AC.jpg";
// NSURL *url2 = [NSURL URLWithString:encodeStr];
// NSURLComponents *component = [NSURLComponents componentsWithURL:url2 resolvingAgainstBaseURL:NO];
NSURLComponents *component = [NSURLComponents componentsWithString:encodeStr];
NSString *path = component.path;
NSLog(@"path=%@",path);
The user component of a URL is an optional component that precedes the host component, and ends at either a colon (if a password is specified) or an @ sign (if no password is specified). For example, in the URL http://username:password@www.example.com/index.html#jumpLocation, the user component is username the pass component is password the host component is www.example.com the path component is /index.html the fragment is jumpLocation
