写在前面：本文旨在解决OC中字符串的编码解码问题，并非是HTML5或者其语言的转码问题。

特殊字符编码解码

Foundation框架

- (NSString *)ocstringEncode:(NSString *)str {
    
    return [str stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet characterSetWithCharactersInString:@"#%<>[\\]^`{|}\"]+"].invertedSet];

//    在对URL中的中文进行转码时，在iOS 9之前我们使用
//    [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
//    在iOS 9之后使用：
//    [str stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];    

//    NSCharacterSet其他类方法的所代表的特殊字符串
//    URLFragmentAllowedCharacterSet  @"#%<>[\]^`{|}"
//    URLHostAllowedCharacterSet      @"#%/<>?@\^`{|}"
//    URLPasswordAllowedCharacterSet  @"#%/:<>?@[\]^`{|}"
//    URLPathAllowedCharacterSet      @"#%;<>?[\]^`{|}"
//    URLQueryAllowedCharacterSet     @"#%<>[\]^`{|}"
//    URLUserAllowedCharacterSet      @"#%/:<>?@[\]^`"

}

- (NSString *)ocstringDecode:(NSString *)str {

    return [str stringByRemovingPercentEncoding];
}

CoreFoundation框架，C语言

- (NSString *)stringEncode {
    NSString *encodedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)self, NULL, CFSTR(":/?#[]@!$ &'()*+,;=\"<>%{}|\\^~`"), kCFStringEncodingUTF8));
    return encodedString;
}

- (NSString *)stringDecode {
    NSString *result = [(NSString *)self stringByReplacingOccurrencesOfString:@"+" withString:@" "];
    result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    return result;
}

特殊字符编码解码举例

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    NSString *url = @"http://study.minshenglife.com:7100/api/v1/sso?openUser=2Xxad8F+IOEAHrt5K6Lm4w==&openPwd=/luuvx4Q0BQysuMKfE5dMA==曾仕林";
    NSString *str1 = [self ocstringEncode:url];
    NSString *str2 = [self ocstringDecode:str1];
    
    NSString *str3 = [self stringEncode:url];
    NSString *str4 = [self stringDecode:str3];
    NSLog(@"\n%@ \n%@ \n%@ \n%@",str1,str2,str3,str4);
}


- (NSString *)ocstringEncode:(NSString *)str {
    
    return [str stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet characterSetWithCharactersInString:@"#%<>[\\]^`{|}\"]+"].invertedSet];
    
//    在对URL中的中文进行转码时，在iOS 9之前我们使用
//    [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
//    在iOS 9之后使用：
//    [str stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
    
}

- (NSString *)ocstringDecode:(NSString *)str {

    return [str stringByRemovingPercentEncoding];
}


- (NSString *)stringEncode:(NSString *)str {
    NSString *encodedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)str, NULL, CFSTR("#%<>[\\]^`{|}\"]+"), kCFStringEncodingUTF8));
    return encodedString;
}

- (NSString *)stringDecode:(NSString *)str {
    NSString *result = [(NSString *)str stringByReplacingOccurrencesOfString:@"+" withString:@" "];
    result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    return result;
}

打印结果：

encode.png