utf-8、unicode 、nsstring转换

一、nsstring转utf-8

NSString * str1=[@"你好" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

 二、utf-8转unicode

NSString * title=[self utf8ToUnicode:@"你好"];

- (NSString *) utf8ToUnicode:(NSString *)string

{

    NSUInteger length = [string length];

    NSMutableString *s = [NSMutableString stringWithCapacity:0];

    for (int i = 0;i < length; i++)

    {

        unichar _char = [string characterAtIndex:i];

        //判断是否为英文和数字

        

        if (_char <= '9' && _char >='0')

        {

            [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i,1)]];

        }else if(_char >='a' && _char <= 'z'){

            [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i,1)]];

        }else if(_char >='A' && _char <= 'Z'){

            [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i,1)]];

        }else{

            [s appendFormat:@"&#92;u%x",[string characterAtIndex:i]];

        }

    }

    return s;

}